Reingard Seibt
email: seibt@imib.med.tu-dresden.de

Silvia Spitzer

Matthes Blank

Klaus Scheuch

Predictors of work ability in occupations with psychological stress

Keywords: Work ability, Stress, Teacher, Office worker

Aim This study aimed to detect health-and work-related predictors of poor and good work ability in teachers (TE) and office workers (OW). Method Work ability and its influence factors were analyzed in 100 female TE and 60 female OW aged between 25 and 60 years. The work ability was evaluated with the work ability index questionnaire and the health status with the vitality measurement system®. In addition, cardiac risk factors, burnout risk, as well as the working demands and effort-reward ratio were taken into account. Predictors of work ability were analyzed by using a CHAID analysis. The number of complaints represents the best predictor to divide both occupational groups into subgroups with different work abilities (criterion variable). Results Poor work ability is caused by many complaints and cardiovascular risk factors. By contrast, excellent work ability is associated with few complaints, the occupation "office workers," a younger vital functional age, and the absence of burnout symptoms, which means in comparison with OW, TE have a 1.6 times higher risk for impaired work ability. Furthermore, the absence of burnout symptoms is a resource of TE, whereas OWs tend to have a younger vital functional age compared to their calendrical age. Although this analysis is able to explain 61.2% of the influence on impaired work ability, research for further causes must be undertaken.

Conclusion

The results reflect the positive effect of a high educational level and a challenging job on the preservation of good work ability. Moreover, they draw the attention to the psychological and psychosocial strains of TE. TEs are exposed more frequently to feeling overstrained; this probably effects a higher retirement rate due to illness.

Introduction

Work ability is defined as the sum of factors enabling an employed person in a certain situation to manage his/her working demands successfully [START_REF] Ilmarinen | Arbeitsfähigkeit 2010. Was können wir tun, damit Sie gesund bleiben (Work ability 2010. What can we do so that you remain well)? VSA[END_REF]. That means, according to the concept of work ability by [START_REF] Ilmarinen | Arbeitsfähigkeit 2010. Was können wir tun, damit Sie gesund bleiben (Work ability 2010. What can we do so that you remain well)? VSA[END_REF], the personal ability to cope with professional demands successfully is determined by personal resources (education and competence; motivation, attitudes, values) and the requirements of the work situation (gainful employment). It can be looked at both as an individual resource according to well-being and health of the individual and also as an organizational resource, related to a higher quality of work. A high work ability is accompanied with a longer active work life and therefore with low costs for the national social system (Hasselhorn and Müller 2004). Besides qualification and motivation, the health of employees is, however, an indispensable prerequisite for good work ability and satisfaction and consequently also for capabilities and professional success. Premature retirement is one effect of decreased work ability [START_REF] Tuomi | Promotion of work ability, the quality of work and retirement[END_REF].

The work ability of teachers is especially alarming from an occupational medical point of view and should be examined closely. Rates of premature retirement among German school teachers due to serious health disorders are consistently higher than those of other employees in public service (Statistisches Bundesamt 2005). In 2004 only 26% of teachers reached normal retirement age, compared to 54% of other employees in public service (Statistisches Bundesamt 2005). Most of these early pensioned teachers leave their job due to health reasons, particularly psychosomatic or psychic diseases [START_REF] Hillert | Psychosomatische Erkrankungen bei Lehrerinnen und Lehrern. Ursachen -Folgen -Lösungen (Psychosomatic diseases in female and male teachers. Causesconsequences-solutions[END_REF]. Reasons for this are seen in work-related diseases, which can be traced back to the high mental stress and chronic overstraining. But this is not a specifically German problem [START_REF] Brown | Ill health retirement in scottish teachers: process, outcomes and re-employment[END_REF][START_REF] Schwarzer | Teacher burnout in Hong Kong and Germany: A cross-cultural validation of the maslach burnout inventory[END_REF][START_REF] Guglielmi | Occupational stress, burnout, and health in teachers: A methodological and theoretical analysis[END_REF].

The occupational demands of teachers have been very well researched [START_REF] Bauer | Correlation between burnout syndrome and psychological and psychosomatic symptoms among teachers[END_REF][START_REF] Dunham | Stress in teachers: Past, present and future[END_REF]. But the effect of work-related and personal risks and resources on the work ability of teachers has not been well examined [START_REF] Ilmarinen | Ageing workers in the european union. Status and promotion of work ability, employability and employment[END_REF][START_REF] Kyriacou | Stress, health, and school-teachers: A comparison with other professions[END_REF][START_REF] Kyriacou | Teacher Stress: directions for future research[END_REF], and comparisons with other professions and objective data are not available. To evaluate the findings on teachers, it is necessary to compare their work ability with other occupational groups characterized by a similar level of psychological stress, but different levels of education, job specifications, and work-related demands. Office workers were chosen. But both occupational groups are characterized by mainly psychological and social communicative requirements (Huang et al. 2004).

In order to maintain and promote the work ability on a high level over working life, the identification of work-related and personal risks and resources (influence factors) is necessary. This requires a multidimensional approach that can take into account complex occupational and personality factors. Most of the former studies just worked with subjective questionnaires [START_REF] Bauer | Correlation between burnout syndrome and psychological and psychosomatic symptoms among teachers[END_REF][START_REF] Clark | Job burnout and job leaving in public school teachers: implications for stress management[END_REF].

The aim of this study is to examine the work ability and the work-related and personal factors ('risk factors' and 'resources'), especially health factors in grammar school teachers in comparison to office workers. Secondly, it has to be tested which of these factors are relevant predictors for poor and excellent work ability.

Method

Participants

A sample of 100 female grammar school teachers and 60 office workers were recruited in Dresden (Federal Country of Saxony, Germany) from grammar schools (response rate: 58.3%) and in public facilities (response rate: 57.1%) by telephone or personal contact. Mostly the project was presented in a short lecture in the schools and public facilities, respectively. The participants were aged between 25 and 60 years (mean age: 44 ± 9 years).

The groups did not differ in age distribution or marital status (Table 1). The majority of women were married (teachers: 71%, office workers: 72%), and 20% of the teachers as well as 10% of the office workers were divorced. Education and professional training of the groups differed in the following ways. Without exception, all teachers had completed a university education. All of them were employed as civil servants, and 98% belonged to the permanent staff. Thirty-two percent of office workers obtained their end of school exam, whereas only 17% completed a university education, but most of them additionally had vocational training. All office workers were employed as civil servants. More than 80% are permanent workers. Their job profile ranged from pure office work (mainly administration), organizational tasks, and customer care, to advisory service. All of them worked on the computer for more than 4 h daily.

Study design and inventories

Work ability is a result of interaction between occupational (e.g., intensity of work, effort-reward imbalance) and personal (e.g., coping, social competence, behavior under stress), and especially health factors (e.g., vitality, complaints, burnout risk). Therefore, an integrated occupational medical and psychological research method was used to determine predictors of poor and excellent work ability in both groups. This multidimensional method consists of objective (physiological measures) and subjective (questionnaires, structured interview) instruments for the assessment of the work ability and the personal and work-related factors-including the health status (vitality). In order to find predictors of the work ability, CHAID analyses were carried out. CHAID (chi-squared automatic interaction detector) analysis was used to find predictors of poor and excellent work ability. This method divides a population into distinct groups based on the category of the "best" predictor of a dependent variable. Each of these groups is split into smaller subgroups based on other predictor variables. The process continues until no further statistically significant predictors can be found [START_REF] Magidson | The CHAID Approach to Segmentation Modeling: CHI-squared Automatic Interaction Protection[END_REF].

Work Ability Index (WAI)

The WAI is based on a self-assessment of work ability and gives information about the individual health state, the physical and mental demands in the occupation and the capacity of performance [START_REF] Tuomi | Work ability index[END_REF]. The WAI describes how well an employee is capable of doing his/her job [START_REF] Tuomi | Promotion of work ability, the quality of work and retirement[END_REF]. It is recommended as a diagnostic instrument for the development of measures for the health support and the identification of employees who require medical care. The aim is to prevent the premature reduction of work ability. The WAI measures the following seven aspects of work ability:

current work ability compared with lifetime best (WAI 1); work ability in relation to the physical and mental demands in the present work (WAI 2); current number of diseases or injuries diagnosed by a doctor (WAI 3 -51 diseases that are assigned to 14 illness groups afterwards); subjective estimation of work ability impairment due to diseases (WAI 4); sick leave taken in the last 12 months (WAI 5); personal prediction of work ability in the next 2 years (WAI 6) and psychological attitudes and resources to do the job (WAI 7).

The cumulative index of WAI ranges from 7 to 49 points and is divided into the following categories: poor (7 -27 points), moderate (28 -36 points), good (37 -43 points), and excellent work ability (44 -49 points).

Health status

In this study health status includes vitality and burnout risk.

Vitality Vitality is defined as the age-and gender-corrected functional state and the well-being of the whole organism based on the troika of physical, mental, and socioemotional capabilities of a person (Meißner-Pöthig 1997). The Vitality Measurement Station (Vitalitätsmessplatz®: Meißner-Pöthig 1997) is an inventory for the assessment of the health status in accordance with the WHO definition as physical, emotional, and social well being. This diagnostic method is used to identify individual risks and resources, which frequently are in relation to personal habits (e.g., lack of exercise, bad nutritional habits, sensitivity to stress, and stress management). The measuring system is a multidimensional test battery comprising 45 vitality indicators to assess the following functions:

cardiopulmonary system (e.g., blood pressure, pulse at rest and work load, vital capacity, arterial oxygen partial pressure, cardiovascular index after submaximal strain); musculoskeletal system (e.g., muscular strength, speed, coordination capabilities); sense organs (e.g., visual/auditory acuity, visual/auditory reaction capabilities); body composition (e.g., body fat, active cell mass, water ratio, waist hip ratio); psychological and mental dimensions (e.g., verbal/ cognitive response, reorientation capabilities, concentration, flexibility, strategy building, memory capacity); physical and psychological complaints measured by the BFB questionnaire (Höck and Hess 1975) and social factors (obligations and leisure time, behavior under stress, social competence).

The age-related changes of the individual vitality indicators are condensed in a functional age index (FAI)an indication of the vital age. The calculations of the FAI are based on age-and gender-related reference values for a defined reference population in which the calendrical and biological functional age correspond in normally aging persons [START_REF] Meiβner-Pöthig | Referenzstudie zur Vitalitätsdiagnostik[END_REF]. The vital (biological) aging speed can differ considerably.

Maslach Burnout Inventory-General Survey Finally, as an indicator of health status the burnout risk was measured with the questionnaire Maslach Burnout Inventory-General Survey (MBI-GS: [START_REF] Schaufeli | Maslach Burnout Inventory -General Survey (MBI-GS)[END_REF]) developed for use with all occupations other than the human services and education. The MBI-GS subscales emotional exhaustion, cynicism and professional efficiency ranged in a codomain from 0 to 6. A high degree of burnout is reflected in high scores on emotional exhaustion and cynicism and low scores in professional efficiency. To evaluate the burnout risk the instruction from [START_REF] Kalimo | Staying well or burning out at work: work characteristics and personal resources as long-term predictors[END_REF] is used ("no burnout": 0 -1.49 points, "some burnout symptoms": 1.5 -3.49 points, "burnout risk": 3.5 -6 points).

Factors of personality

Sociodemographic factors and habits Determined anamnestic factors and habits (e.g., age, marital status, current complaints, smoking, consumption of alcohol, unfavorable nutritional behavior, and behavior at leisure time) were assessed by means of a self-made structured interview.

Relaxation inability

The inability to relax was examined by using the corresponding subscale of the standardized questionnaire FABA [START_REF] Richter | Das Erleben von Arbeitsintensität und Tätigkeitsspielraum -Entwicklungen und Validierung eines Fragebogens zur orientierenden Analyse (FIT) (Perceived work intensity and activity latitude: Development and validation of a questionnaire (FIT))[END_REF]). This subscale gives information for risk assessment of inefficient coping with demands and disturbed relaxation. The codomain of the score for relaxation inability ranges from 6 to 24. The general cut off for 'noticeable' values is 19 and for "very noticeable" values 21.

Work-related factors

Some occupational factors were assessed by means of a professional case history (self-made structured interview). The participants were asked, for example, about their working conditions and occupational career.

Working demands For measuring the range of job demands (JD) and decision latitude (DL), the FIT questionnaire [START_REF] Richter | Das Erleben von Arbeitsintensität und Tätigkeitsspielraum -Entwicklungen und Validierung eines Fragebogens zur orientierenden Analyse (FIT) (Perceived work intensity and activity latitude: Development and validation of a questionnaire (FIT))[END_REF] was used. It is a screening instrument for the assessment of the coherence between the working situation and the consequences of work. In the result of the questionnaire an occupation can be classified as active (high JD and DL), low strain (low JD and high DL), passive (low JD and DL), or high strain job (high JD and low DL). High strain jobs are connected with an increased risk for cardiovascular diseases, according to [START_REF] Kivimäki | Work stress and risk of cardiovascular mortality: Prospective cohort study of industrial employees[END_REF].

Effort-reward imbalance The effort-reward imbalance at work was measured by the short version of ERI questionnaire with 23 items [START_REF] Siegrist | The measurement of effort-reward imbalance at work: European comparisons[END_REF][START_REF] Siegrist | Adverse health effects of high effort/low reward conditions at work[END_REF]. It is applied to identify chronic effects of psycho-mental and socio-emotional stress and to estimate associated health hazards. The subscale occupational reward measures satisfaction with a three-factorial structure: financial and status-related aspects (1), esteem rewards (2), and gratification of job security (3). If the ratio between effort and reward at work is higher than 1 (high effort and low gratification) a healthy risk can be expected.

Results

Comparison among occupational groups

The work ability of teachers with an average of 39 ± 6 points is significantly lower than the work ability of office workers with an average of 41 ± 5 points (p = 0.001). More teachers than office workers show a poor or moderate (37 vs. 18%) work ability. Good work ability is almost evenly distributed in both occupational groups (50 vs. 53%), but excellent work ability can be found twice as often among office workers than in teachers (13 vs. 28%).

Health risk factors and resources of work ability included in the analysis were diagnosed diseases (Fig. 1), current complaints, relaxing capacities, burnout risk and the ratio of effort and reward at work, but also cardiovascular risk factors (e.g., body mass index-BMI, waist hip ratio-WHR, pulse performance index-PPI), physical and mental 'fitness,' and vital age.

The occupational groups do not differ regarding the number of physical and psychic complaints. That means that teachers do not have more complaints than office workers. However, 68% of the teachers and 60% of the office workers report exhaustion as their most frequent complaint. On average, six physical complaints are reported in both groups (teachers: 6.3 ± 4.6; office workers: 6.4 ± 4.7; p = 0.901). In the psychological field two complaints are stated in both occupational groups (p = 0.513).

Moreover, the frequency of risk factors for cardiovascular diseases of teachers is lower compared with that of office workers (Table 2). High blood pressure is analyzed in almost every second office worker (OW: 47%; TE: 25%; p = 0.033), but only approximately 12 percent of them are treated with antihypertensive medication (Table 2). More than a third of office workers (37%) are overweight, but there is no significant effect (p = 0.199) on teachers (27%). This is reflected in a high proportion of fat in the body composition. In the group of office workers, the proportion of body fat is 23 ± 7 kg on average and thus about 3 kg higher than the fat proportion in the group of teachers (normal range: 10 -17 kg). There is a health risk by the waist hip ratio (WHR: unfavorable fat distribution pattern) for 12% of teachers and 18% of office workers. For the fitness index, the average values of the groups are above the value of 2, which corresponds to a good fitness. The similar composition of the active body cell mass (e.g., muscle mass) indicates a comparable fitness as well.

The functional age index (a construction of the measured vitality indicators), which mirrors the vital age, shows that teachers (40.6 ± 8.0 years) compared with their calendrical age (44.6 ± 7.7 years) have a younger vital age, whereas in office workers the vital age (44.5 ± 5.3 years) corresponds to their calendrical age (42.6 ± 8.7 years). This indicates an obviously better vitality status in teachers than in office workers. The vital functional age of teachers is strongly affected by their excellent mental capacities (e.g., flexibility, concentration, strategy building, memory capacities), a better physical fitness (pulse performance index), and in this way a good training status of their cardiovascular system (resources). Despite the fact that teachers are generally marked by more job-related and everyday job demands and a lower proportion of leisure time than can be assessed for office workers, they use their leisure time actively to keep up their physical fitness and well-being.

For the total value of the burnout risk, significant differences result from the occupation. Teachers (1.7 ± 0.7 points) have significantly (p = 0.000) higher values in burnout risk in comparison to office workers (1.2 ± 0.8 points). A distinctive burnout risk (3.5 points) is available merely in 3% of office workers, but more than 50% of teachers. Only approximately a fourth of office workers show burnout symptoms (Table 3). In teachers there is a proportion of emotional exhaustion that is twice as high as in office workers (34% vs. 17%; p = 0.000). Unlike office workers, teachers achieve the significantly highest values for relaxation inability (17.1 vs. 13.5 points; p = 0.000); 31% have a 'noticeable' or 'very noticeable' relaxation inability (Table 3), while in office workers high values are found for only 7% (p = 0.000).

Furthermore, significant differences between the occupations in range of job demands and decision latitude could be determined. Teachers differ from office workers by a bigger range of job demands (teachers: 3.3 ± 0.3; office workers: 3.1 ± 0.5; p = 0.010) and a higher decision latitude (teachers: 3.1 ± 0.5; office workers: 2.8 ± 0.6; p = 0.001). According to the classification of Karasek [START_REF] Karasek | Job demands, job decision latitude and mental strain: Implications for job redesign[END_REF][START_REF] Karasek | Healthy work. stress, productivity and the reconstruction of working life[END_REF], 90% of teachers can be found in an active job and 10% in a low strain job. The distribution of the office workers varies more strongly. The office workers can be classified to all categories except the passive job (active job: 65%, low strain job: 27%, high strain job: 8%).

Despite inferior difference, teachers (0.7) report a significantly (p = 0.008) stronger effort-reward imbalance than office workers (0.6). This more unfavorable effortreward imbalance in the group of teachers results from the effect that teachers tend to overexert more strongly in their occupation than office workers, but teachers get a comparable recognition from the occupational field (Table 3). However, the ERI mean values classified are quite safe. There is a health risk for only 7% of teachers (office workers: 0%; p = 0.036).

Predictors of work ability

At first, correlation and regression analyses were carried out in order to test the association between personal factors, work-related factors and the work ability of teachers and office workers (Table 4). Significant low rise to middle correlations [START_REF] Bühl | SPSS Version 12. Einführung in die moderne Datenanalyse unter Windows[END_REF] was determined between work ability and current complaints (r = -0.54), burnout risk (r = -0.54), relaxation inability (r = -0.41), as well as the effort-reward imbalance (r = -0.33) and the physical fitness index (r = 0.21); significant very low correlations are still found for memory performance (r = 0.18), fat mass (r = -0.16), BMI (r = -0.16), and WHR (r = -0.15).

Due to their meaningfulness these variables were included in the CHAID analyses [START_REF] Magidson | The CHAID Approach to Segmentation Modeling: CHI-squared Automatic Interaction Protection[END_REF] for determining relevant predictors for work ability: current complaints, relaxation capacities, burnout risk, and the effort-reward ratio at work, but also cardiovascular risk factors (BMI, WHR, PPI), physical and mental 'fitness,' and the vital functional age. The result of this analysis is represented for the complete sample of the teachers and the office workers as a classification tree (tree diagram) that shows how major "types" formed from the independent variables differentially predict the criterion variable (Fig. 2). The best predictor is the one with the lowest significance value.

According to this analysis, the significant factors on work ability are the following: physical and mental complaints (BFB questionnaire: p=0.000), fitness index (PPI: p=0.000), occupational group (p=0.003), waist hip ratio (WHR: p=0.001), classified burnout risk (p=0.001 and p=0.013), and vital functional age (FAI: p=0.042). In this model 61.2% of the complete variance is explained with the work ability (WAI score) in occupational groups with psychological stress. Based on significant predictors, future work ability is forecast (Fig. 2).

Impaired (poor) work ability is mainly associated with an increased number of physical and mental complaints (BFB questionnaire), a moderate fitness status of the cardiovascular system, and an unfavorable classification of the waist hip ratio. By contrast, excellent work ability is associated with few physical and mental complaints (BFB questionnaire), the occupation "office workers," a younger vital functional age, and the absence of burnout symptoms. The number of current complaints seems to be the strongest factor in both groups for impaired work ability. In comparison to office workers, teacher have a 1.6 times higher risk for impaired work ability.

Additionally, the same CHAID analysis was tested without the variable current complaints; the variable burnout risk became the predictor that is associated the most with the work ability. If the WAI score was calculated without the subscale WAI 3 (current number of diseases or injuries diagnosed by a doctor), the results in the tree diagram hardly changed. Here, the number of current complaints was identified again as the main predictor for impaired and high work ability, respectively.

Summarizing these findings, poor work ability can be found in both occupational groups. It is especially related to physical risk factors. Excellent work ability can be found among teachers with high mental resources and among office workers with young vital functional age. After all, 43% of office workers show excellent work ability (WAI:

Discussion

In general, teachers differ from office workers in terms of more unfavorable effort-reward imbalance (ERI) and a higher proportion of emotional exhaustion and cynicism (MBI-GS). More than 58% of teachers, but only 25% of office workers show burnout symptoms as a result of jobrelated strain (p=0.000). However, in no case a full burnout syndrome could be found. In addition, teachers have higher relaxing capacities than office workers (FABA: sum score >17 points). Especially the combination of high exhaustion and a higher level of relaxation inability are threatening to people's health as their free time does not offer enough recreation after a working day. Some of the teachers and office workers have physical impairments. Cardiovascular risk factors and the burnout components, which can express themselves in a considerable restriction of the work ability and in emotional illnesses, are of special relevance. Only 14% of the teachers take part in a general work preventive medical checkup, and only 5% of them use psychotherapeutic counseling.

The permanent state of imbalance between efforts made at work and reward gained can lead to stress reactions (e.g., stress or activations of the central nervous system), which have to be considered as health risks. This effort-reward imbalance has to be regarded as an additional health risk in 7% of teachers. Admittedly, there is a discrepancy between teachers' subjective estimation of work ability and their vitality status. A significantly lower work ability among teachers than among office workers can be assessed, although their vital functional age index is much younger compared to office workers. This indicates a different speed of aging among teachers and office workers, but also a connection to education and occupational demands. This range illustrates once more that the speed of agingindependent of the occupational group-can vary considerably in each individual case (different 'vitality patterns').

The results of health status (vitality) reflect the effects of work-related demands and an unhealthy lifestyle. But they also indicate resources for the preservation of the work ability. The vital functional age of teachers, for instance, is strongly influenced by mental performance capabilities and physical fitness. These factors promote the ability to cope with occupational demands.

'High' education has positive effects on preservation of nearly all performance features. In addition to the high education level, the continuous training of mental capacities, as is characteristic for grammar school teachers, is beneficial to the preservation of the high mental performance capacities. This is because functions that are frequently used remain at a high level for a long time ("use hypothesis"). This is not only true for the training of physical capacities, but also for mental and social capabilities. There is an occupational transfer effect assumed. The high level of work-related mental demands in teachers allows the transfer of these effects to other non-occupational abilities [START_REF] Welford | Thirty years of psychological research on age and work[END_REF]). According to [START_REF] De Staufer | Ältere Beschäftigte und technischer Wandel. Computereinsatz im Büro-Maßnahmen betrieblicher Unterstützung (Older employees and technical change. Use of computers in the office, measures of operational support). Hogrefe, Göttingen The Sixth Report of the Joint National Commitee on Prevention, Detection, Evaluation and treatment of high blood pressure[END_REF], teachers are more sensitive to changes (e.g., weakness of memory) than other occupational groups.

In both groups impaired work ability is closely related to a high number of physical and mental complaints and physical risk factors (PPI, WHR). Excellent work ability among teachers is mainly marked by mental resources (no burnout risk), whereas it is characterized by a young vital functional age (FAI) among office workers. In comparison with office workers, the teachers have a 1.6 times higher risk for impaired work ability (WAI <37 points).

Teachers more frequently than other occupational groups suffer from diseases that develop from mental and emotional stress. Therefore, teachers show a high risk of psychosomatic and psychic diseases. As reasons for it, primarily work-related chronic overload is discussed. As a rule, office workers have a considerably lower mental and emotional stress, and thus also a lower risk for reduced work ability.

In order to identify relevant risk factors and resources in both occupational groups, an integrated occupational medical and psychological research method has proved useful as health risks and resources at work are multidimensional. However, it is only one sphere of influence of work ability. In order to find other reasons for impaired work ability, more factors have to be taken into accountespecially vitality, but also individual habits (diet, fitness, leisure time) and personal coping capabilities, such as recreational capacities, burnout risk, stress management, as well as effort and reward on the job [START_REF] Mearns | Relationship between teachers' occupational stress and their burnout and distress: roles of coping and negative mood regulation expectancies[END_REF][START_REF] Gaziel | Coping with occupational stress among teachers: a cross-cultural study[END_REF]. The assessment of different vitality functions in particular allows a focused intervention that considers the individual lifestyle. If the prognostic significance of WAI for the occurrence of occupational disabilities is taken into account, it can be concluded-considering the described risk factors-that teachers are more likely to retire early from their job due to health reasons.

Summarizing, it can be said that long-lasting work ability requires long health. Preventive measures are necessary to protect and promote employees' health. According to the German Labor Protection Law (Arbeitsschutzgesetz 1996), the health of the teachers has to be supported and preventatively protected. However, the realization of such a support varies strongly in the different federal states. Preventative measures for the receipt and support of work ability should include both personal and work-related factors. The professional specific of teachers is not taken into account sufficiently in work medical prevention and in diagnostics or therapy until now. For this occupational group, there are no generally accepted methods to analyze medical risks. There are still no methodical and structural prerequisites for an effective and efficient employees' medical support.

The integrated occupational medical and psychological research method is able to identify work and person-related risk factors and resources of occupations with psychological stress because both health risks and resources vary at work. To sustain and promote work ability, not only workrelated risks, but also lifestyle, health behavior (e.g., diet, stress prevention), and individual resources should be the focus. Depending on the individual diagnosis, it is possible to recommend certain training methods and programs of sports medicine, and instructions for stress and life problem management.

Fig. 1

 1 Fig. 1 Frequencies of diseases [%] (WAI 3) for teachers (n=100) and office workers (n=60)

Fig. 2

 2 Fig. 2 CHAID analysis (SPSS Answer Tree)-predictors of poor or excellent work ability for teachers (n=100) and office workers (n=60)

Table 1

 1 Anamnestic characteristics of teachers and office workers

	Anamnestic	Teachers	Office workers	Significance
	characteristics	(n=100)	(n=60)	p-value
	Age [years]	44.6±7.7 42.6±8.8	0.124
	Marital status [%]
	-Single	8	13	0.123
	-Married	71	72
	-Divorced	20	10
	-Widowed	1	5
	Vocational education [%]
	-No vocational education 0	0	0.001***
	-Vocational training	0	73
	-Polytechnic	0	10
	-University	100	17
	***p<0.001
	(Means and standard deviations; frequencies [%])

Table 2

 2 Selected risk factors for cardiovascular diseases in teachers and office workers

	Analyzed risk factors for cardiovascular diseases	Teachers (n=100)	Office workers (n=60)	Significance p-value
	Blood pressure
	Systolic blood pressure [mmHg]	125.0±15.3	129.8±13.6	0.048*
	Diastolic blood pressure [mmHg]	80.6±8.6	84.8±9.1	0.005**
	-Hypertension (>140/90 mmHg) 1 [%]	25.0	46.7	0.033*
	-Antihypertensive medication [%]	12.0	11.7	0.950
	Fitness
	Fitness index (PPI) a	2.1±0.8	2.1±0.6	0.994
	-PPI<1 (poor) [%]	7	2	0.414
	-PPI>2 (good) [%]	50	57
	Body measures
	Body fat mass [%]	20.4±7.3	22.7±7.2	0.086
	Active body cell mass [%]	25.2±2.6	25.4±3.1	0.195
	Body mass index (BMI) [kg/m 2 ]	23.7±3.3	24.3±3.8	0.299
	-Overweight (BMI ≥25 kg/m 2 ) 2 [%]	27.0	36.6	0.199
	Waist hip ratio (WHR)	0.79±0.6	0.80±0.5	0.440
	-Metabolic risk (WHR>0.85) 2 [%]	12.0	18.3	0.272
	a PPI = Pulse performance index: ratio of pulse frequency difference (pulse at work load minus pulse at rest) to duration of work load
	*p<0.05; **p<0.01
	1 The sixth report of the Joint National Commitee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (1997). Archives of
	Internal Medicine, 157: 2413-46

2 Deutsche Adipositas-Gesellschaft, Deutsche Diabetes-Gesellschaft, Deutsche Gesellschaft für Ernährung. (2005). Evidenz basierte Leitlinie-Prävention und Therapie der Adipositas (German Adiposity Association, German Diabetes Association, German Association for Nutrition. Evidence-based guideline-prevention and therapy of adiposity) (Means and standard deviations; frequencies [%])

Table 3

 3 Burnout risk in teachers and office workers

	Burnout risk (0 -6 points)	Teachers (n=100)	Office workers (n=60)	Significance p-values
	Total score (weighted) [points]	1.7±0.7	1.2±0.8	0.001***
	-Single symptoms (1.50 -3.49 points) [%] a	58	22	0.001***
	-Total burnout (≥3.50 points) [%] a	0	3

a Assessment rule and classification of the burnout risk from Kalimo et al. (2003) ***p<0.01 (Means and standard deviations; frequencies [%])

Table 4

 4 Selected personal and work-related risk factors in teachers and office workers

	Analyzed parameters	(n=100)	Office workers (n=60)	Significance
				p-values
	Relaxation inability (6 -24 points)
	Total sum [points]	17.1±3.7	13.5±3.8	0.001***
	-Noticeable sum (19 -24 points) [%] a	31	7	0.001***
	Working demands b
	Job demands (JD: 1 -4 points)	3.3±0.3	3.1±0.5	0.010**
	Decision latitude (DL: 1 -4 points)	3.1±0.5	2.8±0.6	0.010**
	-Passive job (JD: <2.5, DL: <2.5) [%]	0	0	0.029*
	-Low strain job (JD: ≥2.5, DL: <2.5) [%]	10	27
	-Active job (JD: ≥2.5, DL: ≥2.5) [%]	90	65
	-High strain job (JD: <2.5, DL: ≥2.5) [%]	0	8
	Work-related effort-reward ratio c
	Effort (6 -30 points) c	17.1±4.3	14.7±3.6	0.001***
	Reward (11 -55 points) c	48.6±5.1	47.5±6.3	0.378
	Effort-reward imbalance (ERI)	0.65±0.2	0.56±0.2	0.008**
	-Health risk (≥1) [%] c	7	0	0.036*
	a Classification of the recuperation incompetence from Richter et al. (1996)
	b Classification of the job demands and decision latitude from Richter et al. (2000)
	c Classification of the effort-reward imbalance from Siegrist (1996)
	*p<0.05; **p<0.01; ***p<0.001
	(Means and standard deviations; frequencies [%])

J Public Health (2009) 17:9-18

J Public Health (2009) 17:9-18

Conflict of interest statement

The authors disclose any relevant associations that might pose a conflict of interest.


Rik J H Soeteman
email: soetwaay@xs4all.nl

C Joris

Peter M M Spreeuwenberg

Tina Dorn

Jan J Kerssens

Wil J H M Van Den Bosch

Jouke Van Der Zee

C J Yzermans
email: j.yzermans@nivel.nl

Does disaster affect immigrant victims more than non-immigrant victims in Dutch general practice: a matched cohort study

Keywords: Disasters, Ethnicity, Morbidity, Longitudinal studies, General practice

Background In the literature, immigrant victims appear to be more vulnerable to health effects of a disaster than indigenous victims. Most of these studies were performed without pre-disaster measurement and without using a control group. Aim The objective of the study is to monitor differences between two groups of victims, Turkish immigrants and indigenous Dutch, in utilization and morbidity as presented in general practice after a man-made disaster. Methods A matched cohort study was performed with predisaster (1 year) and post-disaster (4 years) measurements of patients from 30 general practices in Enschede. Turkish victims (N=303) and Dutch victims (N=606), matched on age, gender and socioeconomic status, were included. Main outcome measures were psychological problems and physical symptoms as recorded by the general practitioner, using the International Classification of Primary Care (ICPC). Results The Turkish victims showed higher utilization than the Dutch victims prior to the disaster. In the 1st postdisaster year, both groups of victims showed an increase in utilization, but the increases did not differ significantly. The Turkish group showed no significantly greater increase than the Dutch group in the five most prevalent clusters of health problems (psychological, respiratory, skin, musculoskeletal, and digestive). Conclusion The Turkish victims in general practice were as vulnerable as the Dutch victims for the effects on their health of this man-made disaster. Differences between Turkish and native Dutch victims of this man-made disaster can largely be explained by the differences that existed already before the disaster.

Introduction

Turkish migrants first arrived in the Netherlands in the 1960s, and a new generation settled in later decades in order to reunite with their compatriots. They had lived in a rural area and entered a country with a different culture and habits while they were separated from their families at home. In general, they performed unskilled jobs that were rejected by the native Dutch population.

This study monitored the impact of a major disaster on the health of this migrant group, an important minority in the city. The disaster took place on 13 May 2000 in the city of Enschede, which is located in the Eastern part of the Netherlands. A fireworks depot situated in a residential neighbourhood exploded on that day, killing 18 residents and 4 fire-fighters and injuring around 1,000 other people. Some 1,200 victims, one-third of them with Turkish backgrounds, lost their homes and had to be relocated for a long period. A total of approximately 12,000 peopleresidents, passers-by, and rescue workers-were affected by the disaster.

The present study examined the health problems of Turkish victims on the basis of the electronic medical records (EMRs) kept by general practitioners (GPs). Turkish immigrants in the Netherlands are known to have higher utilization rates of general practice than the native population [START_REF] Deville | Perceived health and consultation of GPs among ethnic minorities compared to the general population in the Netherlands[END_REF][START_REF] Stronks | Immigrants in the Netherlands: equal access for equal needs?[END_REF][START_REF] Uiters | Use of health care services by ethnic minorities in The Netherlands: do patterns differ?[END_REF], and they present more digestive, eye, musculoskeletal, respiratory, and skin problems than the indigenous Dutch inhabitants [START_REF] Weide | Migrants in family practice: their symptoms and diagnoses differ from the Dutch (in Dutch)[END_REF]. In addition, they more often present with psychological problems [START_REF] Weide | Migrants in family practice: their symptoms and diagnoses differ from the Dutch (in Dutch)[END_REF][START_REF] Van Der Linden | Symptoms and diseases in the population and in general practice[END_REF].

In a Dutch interview-based study, primary findings with Turkish immigrants were that need and predisposing factors as mental and physical health and sociodemographic characteristics predicted health care consumption [START_REF] Kamperman | Migrant mental health: a model for indicators of mental health and health care consumption[END_REF]. Moreover, migrant specific factors were found among these Turkish immigrants. If the acculturation process (integration of its own culture and the new one of the host country) was not successful, specific characteristics (being insecure about its own cultural roots, no social relations with Dutch people) were associated with the presence of mental disorders.

The disaster literature shows that ethnic minority groups have been described with higher rates of post-disaster mental health problems than other groups [START_REF] Norris | 60,000 disaster victims speak: Part I. An empirical review of the empirical literature, 1981-2001[END_REF][START_REF] Bolin | Older people in disaster: a comparison of black and white victims[END_REF][START_REF] Fothergill | Race, ethnicity and disasters in the United States: a review of the literature[END_REF][START_REF] Galea | Hispanic ethnicity and post-traumatic stress disorder after a disaster: evidence from a general population survey after September 11, 2001[END_REF][START_REF] Garrison | Posttraumatic stress disorder in adolescents after Hurricane Andrew[END_REF][START_REF] Greca | Children's predisaster functioning as a predictor of posttraumatic stress following Hurricane Andrew[END_REF][START_REF] Lonigan | Children's reactions to a natural disaster: Symptom severity and degree of exposure[END_REF][START_REF] Perilla | Ethnicity, culture, and disaster response: identifying and explaining ethnic differences in PTSD six months after Hurricane Andrew[END_REF]. However, these studies did not make use of pre-disaster assessments. It has therefore been unclear, whether post-disaster health differences between immigrant and non-immigrant groups can be attributed to the disaster experience or already existed before the event.

The current population-based study offered a unique opportunity of studying the health of the Turkish disaster victims. They could be followed prior to and following the disaster due to the circumstance that general practitioner records already were operational before the disaster occurred. As a consequence, pre-disaster baseline data on health were available, and pre-post comparisons could be made. The objective of this study was to examine whether Turkish victims presented stronger increases of GP utilization and health problems following this disaster than indigenous Dutch victims.

The research questions of the present study were:

1. Do Turkish and Dutch victims present increases of contacts in general practice services in a period following the Enschede fireworks disaster and do they present more problems and symptoms? 2. Do Turkish victims demonstrate greater increases in contacts in general practice services and in presenting problems and symptoms than Dutch victims?

Methodology

General practitioners

In the Netherlands, every citizen is registered with one GP, who acts as a gatekeeper to secondary care. As a result, victims of this disaster and their medical histories were already known to their GPs in the period prior to the disaster, and it was possible to collect data for this study relating to 1 year prior to the disaster. All GPs participating in the study were already using a computerized information system. All 60 GPs in the town of Enschede were invited to participate, and 44 of them agreed to do so. The 16 GPs who did not participate gave three different reasons; 6 expected an increase in workload, 9 had no victims in their practices, and 1 did not use an electronic data system.

Patients

Persons were marked as victims in their GPs' patient registers by the zip code of their home at the disaster date and when they were registered in the database of the municipal Information and Advice Center (IAC). At the IAC, people were registered as victims on the basis of the municipal identity register or when they considered themselves victims. They all received a research number (barcode), through which they could be monitored anonymously in the GPs' database. Victims' immigrant status was documented at the IAC. The victims were registered as being Turkish whenever they had been born in Turkey or one or both parents had been born there. Victims were excluded (for both groups) if they belonged to other immigrant groups than the Turkish. Victims of all ages were included in the study, but they had to be registered with their GP's practice during the entire study period from 13 May 1999 until 13 May 2004.

People in the Netherlands with lower or middle incomes, 64% of the general population (van der [START_REF] Van Der Linden | Symptoms and diseases in the population and in general practice[END_REF], were covered by a public health insurance scheme until 2006. The fact that the type of insurance was recorded in the GPs' patient records provided us with a crude indicator of socioeconomic status (SES). We matched for the characteristics of age, gender, and insurance type. A minimum of two Dutch victims was required for each Turkish victim, in order to create an appropriate availability of matches on all three covariates. Finally, 303 Turkish victims (and 606 Dutch ones) were included and monitored for 5 years.

Patients were informed about their GPs' participation in this study by posters and leaflets in the waiting room and could object to the use of their anonymized data (but nobody did). Data collection was performed in accordance with the privacy protection procedures of the Dutch data protection authority [START_REF] Roorda | Postdisaster health effects: strategies for investigation and data collection. Experiences from the Enschede firework disaster[END_REF]).

Procedures

Dutch general practitioners use the International Classification of Primary Care [START_REF] Lamberts | International classification of primary care[END_REF], a multiaxial classification system that allows registering diagnoses as well as problems and symptoms.

Symptoms and diagnoses recorded during patient contacts were extracted for the purposes of this study and were grouped in clusters, the psychological, respiratory, skin, musculoskeletal, and digestive clusters. These clusters were organ-based and were known to be the most prevalent [START_REF] Weide | Migrants in family practice: their symptoms and diagnoses differ from the Dutch (in Dutch)[END_REF][START_REF] Van Der Linden | Symptoms and diseases in the population and in general practice[END_REF]).

Statistical analysis

The study period started 1 year before the disaster occurred and lasted 4 years post-disaster. Demographic data on the two victim groups were compared using chi-square tests. Utilization was calculated on an annual basis as the mean number of contacts (face to face and by telephone). The model compared differences in prevalence rates of each post-disaster year compared with the pre-disaster baseline year. The prevalence rates for health problems in the six most prevalent clusters were calculated as the percentage of victims, Turkish and Dutch, visiting their GP for those health problems at least once in a 1-year period.

The data were analyzed using a multilevel model for repeated measurements (level 1, measurement occasion; level 2, person; level 3, general practice). In the random part, the influence of the GPs was modeled as one overall between GP variance at the highest level. At the level below that, i.e., the person level, the error variance for each occasion was modeled together with all the co-variances between the occasions, which controls for the autocorrelation between measurement occasions within persons. In the fixed part, five measurement occasion intercepts were estimated for both groups. The three control covariates (age, gender, insurance) were also modeled as fixed effects and centered around their means.

A Poisson regression model was used for utilization. The models for morbidity were suitable as logistic models. All analyses were performed with MLWIN2.02, using penalized quasi-likelihood (PQL) with second order and an extra dispersion parameter. Contrasts with a Wald test were used to test the hypothesis that prevalence rates and utilization observed in Turkish victims increased by a higher rate than in Dutch victims.

Results

The Turkish immigrant group and the Dutch group were equal regarding socio-demographic factors (Table 1).

Turkish victims had higher pre-disaster utilization than Dutch victims, and both groups of victims showed significant increases during the 1st year post-disaster (P< 0.001, Table 2). The utilization in both groups in the 2nd, 3rd and 4th years was higher than pre-disaster, but the increase seen in Turkish victims in the 2nd and 4th years post-disaster was not significantly greater than the increase observed in Dutch victims. This means that the disaster had an equal impact on both groups.

Both groups of victims displayed significant postdisaster increases of psychological problems (P<0.001, Table 3) in all 4 years, with a peak in the 1st year. But when these increases observed in Dutch victims and in Turkish victims were compared to each other, no significant differences were found again. In the year prior to the disaster, Turkish victims presented fewer psychological problems than the Dutch victims.

After the disaster had occurred, the Turkish victims showed two changes in the physical symptoms that were presented to the GP. One concerned a significant decrease in respiratory symptoms in the 1st year post-disaster as compared with the pre-disaster year. This deviation from the pre-disaster baseline differed significantly from the increase found in Dutch victims (P<0.05). In addition, a significant increase in musculoskeletal symptoms was seen in Turkish victims during the 1st post-disaster year, although this increase was not significantly larger when compared with the increase of the Dutch victims. No significant post-disaster increases were found for symptoms of the digestive system and the skin for either of the groups.

In the pre-disaster year, Turkish victims showed a higher extent of all symptoms than the Dutch.

Discussion

The aim of our study was to explore whether victims of Turkish background had more GP contacts and presented significantly more health problems in the aftermath of a man-made disaster than native Dutch victims. We considered the number of contacts in general practice, psychological problems, and physical symptoms as outcome measurements; all related to their pre-disaster baseline levels. The post-disaster increases on utilization of general practice services and on psychological problems and physical symptoms were comparable in Turkish and in Dutch victims, whereas the Turkish had higher levels than the Dutch prior to and following the disaster. The finding of an equivalent association between experiencing the disaster and health problems between immigrants and indigenous contradicts the conclusions of many studies [START_REF] Bolin | Older people in disaster: a comparison of black and white victims[END_REF][START_REF] Galea | Hispanic ethnicity and post-traumatic stress disorder after a disaster: evidence from a general population survey after September 11, 2001[END_REF][START_REF] Garrison | Posttraumatic stress disorder in adolescents after Hurricane Andrew[END_REF][START_REF] Lonigan | Children's reactions to a natural disaster: Symptom severity and degree of exposure[END_REF][START_REF] Perilla | Ethnicity, culture, and disaster response: identifying and explaining ethnic differences in PTSD six months after Hurricane Andrew[END_REF][START_REF] Drogendijk | Turkish victims of the Enschede firework disaster: A comparative study (in Dutch)[END_REF], which demonstrated that ethnic minority groups were more at risk of psychological problems. The question, however, is how to explain this finding? A major methodological difference between these studies and the present one is that they did not use a pre-disaster measurement. In our study, we had baseline pre-disaster data to our disposal in a prospective design. If we had commenced our analysis after the disaster, we would quickly have assumed that the disaster had a greater effect on the Turkish victims than on the Dutch victims, an erroneous conclusion easily drawn from crosssectional results.

In this study, we demonstrated stronger increases of GP utilization and psychological problems for both victim groups than in another, shorter-term study on the same disaster [START_REF] Soeteman | The course of post-disaster health problems of victims with pre-disaster psychological problems as presented in general practice[END_REF]), which may be explained by the fact that the mean age of the victims in our study was 10 years younger. Younger disaster victims are generally more vulnerable than elderly victims, as stated by Norris in her review [START_REF] Norris | 60,000 disaster victims speak: Part I. An empirical review of the empirical literature, 1981-2001[END_REF]). An explanation for this finding may be 'the inoculation theory': when people get older they become more experienced and have better skills to cope with unexpected life events [START_REF] Ferraro | Psychological resilience in older adults following the 1997 flood[END_REF][START_REF] Knight | Age and emotional response to the Northridge earthquake: a longitudinal analysis[END_REF][START_REF] Norris | Prior experience as a moderator of disaster impact on anxiety symptoms in older adults[END_REF][START_REF] Thompson | Age differences in the psychological consequences of Hurricane Hugo[END_REF]. On the other hand, in a third study on the fireworks disaster population, which was controlled for pre-disaster utilization, no differences due to (younger) age were found for all victims [START_REF] Soeteman | Health problems of women, men and various age groups in family practice after a disaster; a matched cohort study with a predisaster assessment[END_REF]. The lack of control groups of unaffected Dutch and Turkish patients in the Table 3 Prevalence rates (%) of psychological problems, respiratory, skin, musculoskeletal, and digestive symptoms in Dutch and Turkish victims attending their GP at least once per year, from 1 year predisaster (year 0) until 4 years post-disaster (years 1 through 4) current study should be noted in this context too. This was due to the immigrant status being just a variable with the IAC data and not present in the EMR of the GPs, so that we were unable to relate utilization and morbidity to the natural development of "normal" immigrants in general practice acting as controls. Moreover, it should be mentioned that the number of contacts in general practice in the Netherlands had increased throughout the study period [START_REF] Verheij | Netherlands Information Network of General Practice. Facts and figures about general practitioner care in the Netherlands[END_REF], matching the increase seen in the Dutch and Turkish victims studied here. Therefore, the supposed longlasting increased prevalence rates in our study run parallel with this increase in Dutch general practice. In this context, we have to be thoughtful about the time span of disasterrelated health effects of our study. The significant decrease in respiratory symptoms in Turkish victims in the first post-disaster year may be related with the finding that the Turkish already had a high predisaster level of these symptoms, higher than the Dutch victims. However, respiratory symptoms were not found among the health effects of large-scale earthquakes on Turkish victims [START_REF] Basoglu | Traumatic stress responses in earthquake survivors in Turkey[END_REF][START_REF] Basoglu | Prevalence of posttraumatic stress disorder and comorbid depression in earthquake survivors in Turkey: An epidemiological study[END_REF][START_REF] Kilic | Psychological effects of the November 1999 earthquake in Turkey: an epidemiological study[END_REF][START_REF] Livanou | Traumatic stress responses in treatment-seeking earthquake survivors in Turkey[END_REF][START_REF] Tural | Psychological consequences of the 1999 earthquake in Turkey[END_REF]. Only one disaster study on Turkish victims found "trouble in getting breath" as a somatisation symptom [START_REF] Karanci | Psychological consequences of the 1992 Erzincan (Turkey) earthquake[END_REF], and we may not conclude, therefore, that the decrease in respiratory symptoms was culturally influenced, since so little is known about this as a disaster-related finding. The significant decrease in the Turkish victims is a remarkable finding, nevertheless.

The higher level of utilization and extent of physical symptoms in the Turkish victims in the year prior to the disaster was a confirmation of the results of other studies (see Introduction). Some studies suggest an underlying "ethnical factor" (Weide and Foets 1998) as an explanation (genetic factors, specific living and working conditions, the way of presenting problems and doctor-patient communication). Others assume a "condition migrante" [START_REF] Berry | Acculturation and psychological adaptation: an overview[END_REF]Knipscheer 2000a), meaning the conflicts of living between two (religious) cultures, social isolation, and being uprooted, the perception of illness, low socioeconomic status, and discrimination. These factors are summarized in the concept of "acculturation": a dynamic competition between two cultures. Studies often point at socioeconomic differences between the immigrant group and the indigenous population [START_REF] Stronks | Immigrants in the Netherlands: equal access for equal needs?[END_REF]. Finally, in our study, the extent of predisaster psychological problems of the Turkish victims was lower when compared to the Dutch victims, which is in contradiction to other studies [START_REF] Weide | Migrants in family practice: their symptoms and diagnoses differ from the Dutch (in Dutch)[END_REF][START_REF] Dirkzwager | Psychological, musculoskeletal, and respiratory problems and sickness absence before and after involvement in a disaster: a longitudinal study among rescue workers[END_REF][START_REF] Van Der Linden | Symptoms and diseases in the population and in general practice[END_REF]. We assume that this phenomenon (fewer psychological problems and more physical symptoms) may be interpreted as somatization [START_REF] Kamperman | Migrant mental health: a model for indicators of mental health and health care consumption[END_REF]Knipscheer 2000b): psychological distress expressed by physical symptoms.

Conclusions

Although pre-disaster differences exist between victims belonging to the Turkish minority in the Netherlands and ethnic Dutch victims, Turkish disaster victims appear to react as strong as Dutch victims do to a man-made disaster. This idea is supported by one of the participating GPs who, informally, stated the following: "My Turkish patients were already in a bad condition in the period prior to the disaster. They needed more help than the Dutch before the disaster and after it as well." It is obvious that disasters tend to occur more frequently in socially deprived areas [START_REF] Donker | Symptom attribution after a plane crash: comparison between self-reported symptoms and GP records[END_REF][START_REF] Rubonis | Psychological impairment in the wake of disaster: the disaster-psychopathology relationship[END_REF]. Adverse health outcomes in the aftermath of disasters probably originate in the deprivation pre-disaster.

The results of our study plead for an extra effort in assistance if members belonging to any ethnic minority group present more health problems than native citizens. This will concern the provision of supplemental psychological and social help, including the employment of GPs and supporting personnel. This should have been implemented not only after a disaster (den [START_REF] Ouden | Health problems presented in general practice by survivors before and after a fireworks disaster: associations with mental health care[END_REF], but irrespective of any disaster. In our opinion, this will apply for Turkish immigrants in northwestern Europe, but not for other groups, such as Moroccan immigrants, who present with other utilization patterns and other symptoms and problems [START_REF] Kamperman | Migrant mental health: a model for indicators of mental health and health care consumption[END_REF][START_REF] Uiters | Use of health care services by ethnic minorities in The Netherlands: do patterns differ?[END_REF]. The findings of this study demonstrate that general practice can play an important role in detecting health problems presented by both native inhabitants and immigrants prior to and following a disaster. The possibility of retrieving pre-disaster data is a crucial issue in assessing the assumed vulnerability to present health problems of immigrant groups in the aftermath of a disaster.

Table 1

 1 Characteristics of victims registered on their GP's list betweenMay 1999 and May 2004

	Groups of patients	Dutch N=606	Turkish N=303
	% Male	51.2	51.2
	Mean age in years	29.9	29.6
	% low/middle SES	91.7	91.7
	% forced relocation	24.8	27.7
	% no contact	2.6	1.3

SES = Socioeconomic status, as indicated by insurance type

No contact = did not contact GP during study period

Table 2

 2 Utilization rate by Dutch and Turkish victims as mean number of contacts with GPs per year, from 1 year pre-disaster until 4 years post-disaster (years 1 through 4)

	Psychological		Dutch	Turkish	P-value Turkish
					vs. Dutch
	Pre-disaster	Year 0	21.0	12.4
	Post-disaster	Year 1	57.1 ***	41.7 ***	1
		Year 2	39.3 ***	24.7 ***	0.823
		Year 3	46.5 ***	25.5 ***	0.173
		Year 4	37.9 ***	20.0 ***	0.247
	Respiratory
	Pre-disaster	Year 0	17.8	27.9
	Post-disaster	Year 1	18.2	20.7 *	0.048 §
		Year 2	19.4	26.5	0.406
		Year 3	16.2	24.8	0.841
		Year 4	16.1	23.4	0.624
	Skin
	Pre-disaster	Year 0	18.5	21.8
	Post-disaster	Year 1	14.8	19.8	0.532
		Year 2	18.5	23.7	0.617
		Year 3	16.3	25.0	0.162
		Year 4	18.3	21.4	1
	Musculoskeletal
	Pre-disaster	Year 0	19.8	31.2
	Post-disaster	Year 1	22.7	38.7 *	0.442
		Year 2	21.9	30.5	0.439
		Year 3	19.8	33.2	0.663
		Year 4	18.1	26.8	0.617
	Digestive
	Pre-disaster	Year 0	12.1	23.2
	Post-disaster	Year 1	11.8	29.5	0.119
		Year 2	11.8	25.1	0.584
		Year 3	11.1	26.6	0.267
		Year 4	13.8	25.4	0.888
	*P<0.05, year compared with year 0
	**P<0.01, year compared with year 0
	***P<0.001, year compared with year 0
	§P<0.05, Turkish compared with Dutch

J Public Health (2009) 17:27-32

Acknowledgements We gratefully thank the participating general practitioners for registering all contacts in times of pressure.

This study was funded by a grant obtained from the Ministry of Public Health, Welfare, and Sports in the Netherlands.

Conflict of interest statement

The authors disclose any relevant associations that might pose a conflict of interest.


T Kopetsch
email: tkopetsch@kbv.de

The migration of doctors to and from Germany

Keywords: Emigration of doctors, Immigration of doctors, Shortage of doctors

Aim To analyse the role of Germany in the context of the strong international migration of doctors. In doing so, the migration of German doctors abroad and foreign doctors to Germany is qualitatively and quantitatively presented. Subjects and methods The annual statistical reports from the country's medical associations given to the Federal Medical Association were investigated on migratory movements. Furthermore, a survey on how many German doctors are working in these countries was done within relevant organisations in some European countries and the US. Results Germany is affected by an international migration of doctors in two directions. German doctors are emigrating and as well foreign doctors are immigrating. The exchange is not balanced, Germany loses more doctors every year to foreign countries than it gains through immigration. Discussion and conclusions The increasing emigration of German doctors reinforces the shortage of doctors in Germany. In addition, the functioning of the German health system increasingly depends on the immigration of foreign doctors.

Introduction

Many countries that until a few years ago were reporting a glut of doctors are now complaining of a shortage. Germany is one of them. Two separate developments are responsible for this: whilst there is an ever-increasing proportion of older doctors in the German medical profession, the supply of new young doctors is drying up (see [START_REF] Kopetsch | Dem deutschen Gesundheitswesen gehen die Ärzte aus. Studie zur Altersstruktur-und Arztzahlentwicklung[END_REF]. The migration of doctors from and to Germany must be seen in this context. Many German doctors are emigrating because they find their working conditions intolerable. Surveys show that German doctors have three main motives for either emigrating or ceasing to practise curative medicine altogether. The first of these is the level of remuneration, which they consider inadequate for the services they perform. The second is their experience that medical practice allows them too little time for their families and leisure pursuits. Their third motive is the increasing bureaucracy and administrative burden faced by medical practitioners (see Ramboll Management 2004). This shortage of doctors, which has now become a global phenomenon, is linked to a variety of migrations. Some countries, such as the UK and the Scandinavian countries, whose training capacities are too small for the number of doctors required, are using aggressive government-sponsored recruitment campaigns to attempt to lure doctors from other countries, among them Germany, where they are sorely needed. In other countries affected by a shortage of doctors, private employment agencies have sprung up that specialise in recruiting doctors from countries with lower salary levels. Such agencies recruit doctors in Poland, the Czech Republic, Slovakia, and the Ukraine specifically for German, and particularly eastern German, hospitals, which are no longer able to find German doctors to fill their medical vacancies. As a result, the immigration of foreign doctors to Germany has increased in recent years.

Germany is thus affected by this global shortage of doctors not only as a result of the emigration of German doctors, but also in terms of recruiting foreign doctors, with both trends increasing in recent years. This article will therefore analyse the migration of doctors to and from Germany and examine more closely the numbers involved.

Subjects and methods

The annual statistical reports on migratory movements, which were given to the Federal Medical Association by the country's medical associations, were investigated. Furthermore, a survey on how many German doctors are working in these countries was done within relevant organisations in some European countries and the US.

Results

Emigration of German Doctors

Almost every article published about the shortage of doctors in Germany mentions that large numbers of German doctors are emigrating to take up positions in curative medicine abroad. The statistics accompanying these articles attribute different figures on the number of German doctors actually already working abroad. The numbers quoted vary from 6,000 to 15,000, but exact details of the source of information are never given. For this reason, original research was carried out to establish the number of German doctors in the most important countries of emigration. Table 1 shows the results.

This research shows that there is firm evidence of almost 15,000 German doctors working abroad. The actual figure is no doubt higher as it was not possible to include all countries in the study.

Now that the number of German doctors working abroad has been established, the question arises as to whether German doctors have really been emigrating in increasing numbers or whether this perception is due to the growing attention the issue has received.

An initial indication that the number of doctors leaving Germany has indeed recently risen is provided by the increased demand for the "Certificate of Good Standing" (Unbedenklichkeitserklärung). German doctors who want to practise abroad need this document in order to obtain a local employment contract. Statistics collated by the regional medical council in the German state of Hesse show a veritable explosion in the demand for this certificate from Hessian doctors. shows that in 2006 a total of 2,575 doctors who had originally practised in Germany moved abroad. Of these, 78% were German nationals. This represents an increase of 14% in the number of doctors leaving Germany compared with the preceding year. What is astonishing is that the destinations of preference were the German-speaking Switzerland and Austria: 1,106 doctors moved to these countries. By contrast, a total of only 264 doctors emigrated to Scandinavia and the United Kingdom, the countries which the public perceives as attracting increasing numbers of German doctors. Emigration has accelerated in the last few years, the figure for 2001 being only 1,437 (Table 2). The highest percentage of doctors moving abroad was recorded in Baden-Württemberg and Berlin. By far the most popular country of destination is Switzerland (744), followed by Austria ( 272), the USA ( 225), and the UK (143).

We can therefore conclude that there is now sufficient verifiable evidence to prove that the emigration of German doctors has increased considerably in recent years and remains at a remarkably high level.

Migration of foreign doctors to Germany

Anyone trying to estimate or assess the number of foreign doctors in Germany encounters a variety of problems. Doctors who were born in Germany or came as young immigrants, received their schooling, and studied in Germany, but do not have German citizenship appear in the statistics as foreign doctors, although from a professional point of view they should actually count as German. This section of our study is concerned only with those doctors who completed their training in a foreign country and then moved to Germany. However, for the reason given above, it is not easy to generate statistics for this category of physician.

In order to be allowed to practise medicine in Germany a doctor requires a temporary permit (a so-called Berufserlaubnis or 'professional work permit') or a medical licence. Professional work permits are issued on the basis of Sect. 10 of the Federal Medical Regulations (BÄO-Bundesärzteordnung). This leaves the final decision to the discretion of the relevant regional authority, which is obliged to take account of decrees issued by the state government.

Professional work permits are only issued to foreign applicants if they have a professional qualification and also fulfil certain other conditions (e.g., the applicant is a recognised asylum-seeker, a refugee, is married to a German or an EU citizen). Foreign doctors with a professional work permit are not allowed to work independently, but only under supervision. Only a medical licence entitles the holder to practise independently. A licence is issued by the official authorities on the basis of Sect. 3 of the Federal Medical Regulations when the applicant is a German or EU citizen or qualifies as a special case. However, licences are usually only issued to applicants who have long been in the possession of a professional work permit and have already been practising in Germany for several years.

As Fig. 1 makes clear, there are currently 19,513 foreign doctors living in Germany. Of these 13,735, representing 70% of the total, have a medical licence. The remaining 30% practise on the basis of a 'section 10' professional work permit.

However, only 42% of foreign doctors come from the countries of the European Union, while 29% come from other European countries. Of all foreign doctors in Germany, 6,313, or fully 32%, come from the countries of the former east European communist bloc or from former Yugoslavia.

Until 2000 the number of foreign doctors practising in German was growing approximately in line with the general development in the number of doctors. This means that the inflow of foreign doctors has increased noticeably only in the last few years.

The number of foreign doctors who have settled in Germany can be estimated from the registrations of new doctors from abroad recorded by the regional medical councils. As Fig. 2 makes clear, immigration began to increase in 2001 and peaked at just under 2,000 doctors 2 years later. Since then the inflow of foreign doctors has eased. These figures confirm the observation that doctors seeking to emigrate from Eastern Europe are increasingly avoiding Germany and moving directly to the UK and Scandinavia.

The number of foreign doctors practising in Germany rose by a further 6.8% in 2006 (as you can see in Table 3), a growth rate that is thus significantly higher than the average of 2.5% for the years 1994 to 2001 and considerably above the growth rate of 1.2.% for professionally active doctors in general. At 8.5% the growth rate for foreign doctors working in hospitals is particularly high. However, the highest rates of increase for the growth in the number of foreign doctors in hospitals were recorded in the years 2001 to 2003, when they were 11.8%, 13.3%, and 12.3%, respectively. Doctors migrating to Germany come primarily from Austria and the countries of eastern Europe (Figs. 3 and4). A comparison of Fig. 4 with Sect. 2 of this study brings to light a curious phenomenon. While many Austrian doctors emigrate to Germany, Austria is the second most popular emigration destination for German doctors.

In 2006 immigrants accounted for 15% of the registrations of new doctors recorded by the regional medical councils. Although immigration affects the whole country, the percentage in eastern Germany is higher. For example, whereas in 2000 only 5.4% of all foreign doctors in Germany were practising in eastern Germany, in 2006 this proportion had already reached 12.4%.

Table 4 makes clear that the growth in the number of foreign doctors in eastern Germany is many times higher than in the rest of Germany. In the period from 2000 to 2006 the number of foreign doctors in the rest of Germany rose by 26%, while the corresponding figure for eastern Germany is considerably higher at 230%.

Table 5 shows us that between 2000 and 2006 some 1,200 east European doctors moved to eastern Germany and about the same number to the rest of the country. However, because the total number of doctors is much lower in eastern Germany this represents a much higher growth rate there.

The shortage of doctors in Germany is already being particularly keenly felt in hospitals, where many vacancies can only be filled by recruiting foreign doctors. There are reports of hospitals in eastern Germany where three quarters of the medical staff are foreign nationals. The provision of inpatient medical care in eastern Germany could no longer be maintained were it not for a corresponding immigration of east European doctors, especially from Poland, Russia, the Ukraine, the Czech Republic, and Slovakia. The rates of increase for this group were 48.9% in 2002, 90.6% in 2003, and 43.1% in 2004. An influx of foreign doctors is also needed in the rest of Germany. This can be seen from the fact that without immigrant doctors the number of hospital doctors in the rest of Germany would have sunk by 0.2%. This means that the health system in Germany is increasingly dependent on the 'import' of foreign doctors. Without this increased inflow of foreign doctors, which has been observable for the last 6 years, the ability of the German health system to function would be at risk.

Discussion and conclusions

Germany is affected by international migrations of doctors in both directions. German doctors are leaving, while at the same time foreign doctors are entering the country. However, the two movements do not cancel each other out. Every year Germany loses more doctors to emigration than she gains by immigration. The emigration of German doctors is motivated primarily by the higher salaries and better working conditions (regular working hours, flatter hierarchies, etc.) in the countries to which they move (see Ramboll Management 2004). Foreign doctors are primarily attracted by the higher level of pay offered in Germany compared with their homelands.

The situation of the migration of doctors to and from Germany is special, as only a few countries are simultaneously affected in such a substantial way by migration of doctors. Britain and the Scandinavian countries are the traditional immigration countries for doctors, as their training capacity is not sufficient to meet domestic needs. For this reason, in these countries there have been for some time programmes of "structured immigration" that target integration into the workflow, including language acquisition. Those countries will hardly have any problems reported. For Germany, however, the phenomenon of a shortage of doctors and the related increased immigration of foreign doctors is still relatively young. Since no central integration programmes exist, but the immigration and labour absorption is decentralized, there are no specific programmes for structured training on the working procedures in German hospitals and for the systematic improvement of the German language. The often inadequate language skills cause problems, both for patients and for handling day-to-day dealings with the German colleagues. When having patient contact, it may cause misdiagnosis if the patient is not properly understood. The lack of knowledge of the written language often leads to the "paperwork" being done by the German colleagues, which again leads to displeasure.

The most important results of this study are that, firstly, the increasing emigration of German doctors is aggravating the shortage of doctors. Secondly, it can be seen that the proper functioning of the German health system is increasingly dependent on the immigration of foreign doctors.

The lack of doctors in Germany will continue to worsen. First of all, the unfavourable age structure means that many physicians continue to retire. Secondly, the conditions of medical activity, which hold many young doctors back from carrying out curative action, will not significantly improve. Thus, many German doctors will continue to move abroad, and Germany will depend on a high level of immigration. Since the lack of doctors and the willingly increased emigration of German doctors cannot be explained by one cause, one programme for effective counter-measures

Fig. 1

 1 Fig. 1 Development in the number of foreign doctors in Germany

Fig. 4

 4 Fig. 4 Development in the number of practising Austrian doctor

Table 1

 1 German doctors practising abroad

	Country	Year Number Source
	Belgium	2007 338	Federal Public Service for
			Public Health
	Denmark	2004 87	Schneider et al.
	Finland	2006 65	Finnish Medical Council
	France	2006 975	French Medical Council
	UK	2007 4,129	General Medical Council
	Ireland	2004 105	Medical Council Ireland
	Italy	2001 538	Conférence Européenne
			des Ordres des Médecins
	Luxembourg	2001 116	Conférence Européenne
			des Ordres des Médecins
	The Netherlands 2001 584	Ministry of Health, Welfare
			and Sport
	Norway	2004 650	Physician combination
			Norway
	Austria	2007 1,457	Austrian physician chamber
	Portugal	2004 106	Conférence Européenne
			des Ordres des Médecins
	Sweden	2006 1,118	National Board of Health
			and Welfare
	Switzerland	2007 2,565	Association of Swiss Doctors
	Spain	2001 259	Conférence Européenne des
			Ordres des Médecins
	USA	2005 5,830	American Medical Association
	Total	19,054

Table 2

 2 German doctors moving abroad

	Year	Number
	2001	1,437
	2002	1,691
	2003	1,992
	2004	2,731
	2005	2,249
	2006	2,575

Source: German Federal Medical Council

Accordingly, the growth rate in the number of east European doctors practising in Germany was very high: 15.9% in 2002, 16.3% in 2003, and 6.6% in 2004. Thus, the number of east European doctors practising in Germany has doubled since 1998, while the number of Austrian doctors has quadrupled since 1993.

Table 3

 3 Development in the number of foreign doctors in Germany

		Total		Of whom:	Practising		Hospital
	Year	Number	Increase over	Not in medical practice	Number	Increase over	Number	Increase over
			previous year in %			previous year in %		previous year in %
	1998	13,836	0.5	2,847	10,989	-0.9	6,044	-2.3
	1999	14,243	2.9	2,830	11,413	3.9	6,364	5.3
	2000	14,603	2.5	2,952	11,651	2.1	6,581	3.4
	2001	15,143	3.7	2,973	12,170	4.5	7,360	11.8
	2002	16,160	6.7	2,980	13,180	8.3	8,338	13.3
	2003	17,318	7.2	3,145	14,173	7.5	9,360	12.3
	2004	17,991	3.9	3,210	14,781	4.3	10,042	7.3
	2005	18,582	3.3	3,520	15,062	1.9	10,309	2.7
	2006	19,513	5.0	3,433	16,080	6.8	11,186	8.5
	Source: German Federal Medical Council

Table 4

 4 Development in the number of foreign doctors in eastern Germany compared to the rest of the country

		Western Germany (states	Eastern Germany (states
		constituting West Germany	constituting communist
		prior to reunification in	East Germany prior to
		1989)		reunification in 1989)
	Year	Number	Change over	Number	Change over
			previous year		previous year
			in %		in %
	2000	10,969	2.1	682	2.1
	2001	11,405	4.0	765	12.2
	2002	12,217	7.1	963	25.9
	2003	12,763	4.5	1,410	46.4
	2004	12,956	1.5	1,825	29.4
	2005	13,034	0.6	2,028	11.1
	2006	13,821	6.0	2,259	11.4
	Source: German Federal Medical Council

Table 5

 5 Development in the number of east European doctors in Germany

		Western Germany	Eastern Germany
	Year	Number	Change over	Number	Change over
			previous year		previous year
			in %		in %
	2000	2,935	6.0	347	9.8
	2001	3,185	8.5	361	4.0
	2002	3,598	13.0	511	41.6
	2003	3,899	8.4	880	72.2
	2004	3,863	-0.9	1,233	40.1
	2005	3,937	1.9	1,353	9.7
	2006	4,233	7.5	1,505	11.2
	Source: German Federal Medical Council

The number of applications for certificates of good standing rose by a factor of more than ten between the years 2000 (19 applications) and 2005 (104 applications in the first 6 months) (see[START_REF] Köhler | Hessische Ärzte im Ausland 2000-2005[END_REF]. This is, of course, only an indication and not proof that the permanent emigration of German doctors has increased in recent years, since the certificate of good standing is also required when a doctor wants to practise abroad temporarily (e.g., for weekend shifts).However, there is other evidence. For example, in 2000 only 593 German doctors were practising in France. By 2005 this number had risen to 879. A similar development can be perceived in Switzerland, where in December 2003 only 1,474 German doctors were practising, whereas by July 2005 there were already 1,926. In Austria, too, the number of German doctors rose from 547 in 2003 to 786 in 2004.Until a few years ago, the emigration of German doctors was not recorded by the regional medical councils. Since 2001, however, the majority of medical councils has recorded this information and can provide the corresponding data for the outflow of German physicians. The analysis of this data is based on the data filed by these 14 regional medical councils supplemented by a projection for the missing data from the other three councils. The analysis

is not sufficient. A whole set of programmes is necessary to raise the attractiveness of the medical profession in Germany again.

Conflict of interest

The author discloses any relevant associations that might pose a conflict of interest.