D Tountas

Niakas

Evelina Pappa
email: evanpappa@gmail.com

PhD N Kontodimopoulos

PhD A A Papadopoulos

Y Tountas

Assoc Professor

D Niakas

Prescribed drug utilization and polypharmacy in a general population in Greece: association with socio-demographic, health needs, health services utilization and lifestyle factors

Keywords: Drug use, polypharmacy, general population, socio-demographic characteristics, health needs, Greece

Prescribed-drug utilization and polypharmacy in a

general population in Greece: association with sociodemographic, health needs, health-services utilization, and lifestyle factors

Introduction

Drug utilization is the most common medical intervention used to reduce a variety of health risk factors (cardiovascular risk factors), to prevent acute events and to treat diseases. Variation in the pattern of drug utilization, large pharmaceutical consumption, polypharmacy (PP) with the drug-adverse reactions and increased trends of pharmaceutical expenditures are some of the major concerns for health care systems.

Many studies have focused on the prevalence of drug use covering several factors which may influence utilization. Gender differences have been extensively investigated as well as utilization among elderly people who are the major drug users [START_REF] Eggen | Pattern of drug use in a general population-prevalence and predicting factors: the Tomso study[END_REF][START_REF] Del Rio | The use of mediation by the Spanish population[END_REF][START_REF] Eggen | Patterns of medicine use in a general population (0-80). The influence of age, gender, diseases and place of residence on drug use in Norway[END_REF][START_REF] Simoni | The PO River Delta epidemiological study: use of medicines in a general population sample of north Italy[END_REF][START_REF] Fernandez-Liz | Identifying how age and gender influence prescription drug use in a primary health care environment in Catalonia Spain[END_REF][START_REF] Sanfelix | Gender influence in the quantity of drugs used in primary care[END_REF]. Socioeconomic characteristics, health status and health risk factors are important determinants of variations in drug utilization [START_REF] Eggen | Pattern of drug use in a general population-prevalence and predicting factors: the Tomso study[END_REF][START_REF] Bardel | Reported current use of prescription drugs and some of its determinants among 35 to 65 years old women in mid-Sweden: a population -based study[END_REF][START_REF] Furu | Legal drug use in a general population: Association with gender, morbidity, health care utilization and lifestyle characteristics[END_REF][START_REF] Bekke | Self-reported drug utilization, health and lifestyle factors among 70-74 year old community dwelling individuals in Western Norway. The Hordaland Health Study (HUSK)[END_REF][START_REF] Weitoft | Education and drug use in Sweden-a nationwide register-based study[END_REF][START_REF] Nielsen | Prescription and non-prescription medicine use in Denmark: association with socio-economic position[END_REF][START_REF] Fillenbaum | Factors predicting change in prescription and non-prescription drug use in a community residing black and white elderly population[END_REF][START_REF] Henricson | Socioeconomic factors, morbidity and drug utilization-an ecological study[END_REF][START_REF] Gundgaard | Income related inequality in prescription drugs in Denmark[END_REF]. However, few studies have investigated drug utilization in a multivariate framework involving all the abovementioned variables [START_REF] Eggen | Pattern of drug use in a general population-prevalence and predicting factors: the Tomso study[END_REF][START_REF] Furu | Legal drug use in a general population: Association with gender, morbidity, health care utilization and lifestyle characteristics[END_REF][START_REF] Fillenbaum | Factors predicting change in prescription and non-prescription drug use in a community residing black and white elderly population[END_REF].

PP surveys, on the other hand, are age-specific and focused on the elderly population. Previous studies have investigated the determinants of PP, reporting socio-demographic [START_REF] Bjerrum | Polypharmacy: correlation with sex, age and drug regimen[END_REF][START_REF] Thomas | Polypharmacy among older men in South Wales[END_REF][START_REF] Haider | Analysis of the association between polypharmacy and socioeconomic position among elderly aged > or =77 years in Sweden[END_REF][START_REF] Haider | The influence of educational level on polypharmacy and inappropriate drug use: a register-based study of more than 600.000 older people[END_REF], medically-related [START_REF] Thomas | Polypharmacy among older men in South Wales[END_REF][START_REF] Haider | Analysis of the association between polypharmacy and socioeconomic position among elderly aged > or =77 years in Sweden[END_REF][START_REF] Haider | The influence of educational level on polypharmacy and inappropriate drug use: a register-based study of more than 600.000 older people[END_REF][START_REF] Junius-Walker | Prevalence and predictors of polypharmacy among older primary care patients in Germany[END_REF] and health system factors [START_REF] Little | Importance of patients' pressure and perceived pressure and perceived medical need for investigations, referral, and prescribing in primary care: nested observational study[END_REF] as significant predictors of PP use or the adverse effects of PP such as drug reactions and the increasing risks of hospitalization [START_REF] Veehof | Adverse drug reactions and polypharmacy in the elderly in general population[END_REF][START_REF] Alexopoulou | Adverse drug reactions as a cause of hospital admissions: a 6-months experience in a single center in Greece[END_REF][START_REF] Olivier | Hospitalizations because of adverse drug reactions in elderly patients admitted through the emergency department: a prospective survey[END_REF]. There is a lack of consensus on the specific number of drugs required to define PP, which has been defined as simultaneous use of more than one prescribed drug and classified as minor (2-4 drugs) and major (5+ drugs) [START_REF] Bjerrum | Polypharmacy: correlation with sex, age and drug regimen[END_REF], or as long-term with use of two or more drugs for at least 60 days per quarter per year [START_REF] Veehof | The development of polypharmacy. A longitudinal study[END_REF]. Other studies define PP as 6-9 drugs and excess PP (10+ drugs) [START_REF] Jyrrka | Patterns of drug use and factors associated with polypharmacy and excessive polypharmacy in elderly persons: results of the Kuopio 75+ study: a cross-sectional analysis[END_REF] or included OTC remedies [START_REF] Thomas | Polypharmacy among older men in South Wales[END_REF].

In Greece, previous studies on drug utilization were very limited, population and area-specific [START_REF] Antonakis | Seeking prescribing patterns in rural Crete: a pharmacoepidemiological study from a primary care area[END_REF][START_REF] Tzimis | Drug utilization and health behaviours among indigent elderly patients in Crete, Greece[END_REF], whereas PP has not been investigated so far. Drug consumption is very high and there is a rapid increase in pharmaceutical expenditures as a proportion of total health expenditures. According to OECD data [START_REF]OECD Health Data[END_REF], in 2006 pharmaceutical expenditures amounted to 24.8% of total health expenditures, whereas in 1997 this proportion increased to 16.2%. Political measures, such as the list, to control the growth of pharmaceutical expenditure proved ineffective [START_REF] Yfantopoulos | Pharmaceutical pricing and reimbursement reforms in Greece[END_REF]. On this ground, it is very important to study how the drugs are used by the population, which factors affect drug utilization, taking in mind social aspects or whether drugs are being used according to health needs.

The present study was undertaken in order to cover the absence of surveys on medicine utilization and PP in Greece by investigating the prevalence of the self-reported general use of prescribed drugs and PP. Furthermore, the aim was to evaluate, in a multivariate framework, the combined effect of various factors found in previous studies such as socio-demographic, use of health services, health needs and health risk factors relating to lifestyle on prescription drug use and on PP in a representative sample of general population.

Materials and Methods

Study and data

The cross-sectional study took place in September 2006 and involved a sample of adults (>18 years old) residing in urban (>2,000 inhabitants) and rural (<2,000 inhabitants) areas of the country and each of the 13 geographical regions.

According to the latest Population Census (2001), the survey population consisted of approximately 8,880,924 individuals.

Non-fluent Greek speakers, institutionalized subjects and those incapable of reasoning and decision-making on their own were excluded. Participants were grouped, in proportion to the Greek population, by socio-demographic characteristics, according to a three-staged sampling methodology. In the first stage, a random sample of building blocks was selected in proportion to size. In the second stage, households were randomly selected by systematic sampling. In the third stage, an eligible participant was selected by simple random sampling in each household.

In total 1,005 willing subjects, out of 1,388 initially approached (response rate 72.4%), were interviewed by trained interviewers. Thirty seven out of 1,005 participants reported taking only OTC drugs and they were excluded from the analysis because they represented a small group. The reported OTC drugs were analgesics, anti-inflammatory and antacids. The study was focused on the 968 participants. This health survey covered a wide range of information. The questionnaire consisted of five main parts: health-related quality of life measured by the SF-36 Health Survey, health behavior, morbidity, utilization of health services (including drug use) and socio-demographic characteristics.

Measurements

Prescribed drug utilization was measured by the question "Do you currently take some sort of medication on a daily basis?" It was explained to the participants that "currently" referred to the previous 14 days, whereas "daily basis" meant regular or continuous intake of medicines. Answers yes or no to the above question represented use or no use of the drugs respectively. Furthermore, the interviewer recorded the name of the drugs, the dosage form (tablets or injections) and the extent of consumption (e.g. the number of drugs taken). PP was defined as simultaneous use of more than one drug and classified as minor (2-3 drugs) and major (4+ drugs). All the reported drugs were classified under one of the following categories: antihypertensives, antithrombotics, hypolipidemics, antidiabetics, insulin, analgesics, laxatives and psychotropics.

Socio-demographic characteristics

The demographic characteristics were measured by the three categorical variables of gender, age and marital status.

Education and occupation were the two variables measuring the socio-economic status of the participants. Educational level was classified into three levels: primary (reference category), secondary and university level. Occupation was recorded by asking the participants to choose the position best describing their current employment from a list including: employer, employee, retired, other (unemployed, students, and housewives, as reference category). Participants also reported their place of residence (urban/rural).

Health service utilization

The participants were asked to report the number of visits to a general physician, a specialist, a hospital out-patient clinic or if they had been admitted to hospital during the previous twelve months. Up to three visits was considered as normal use while four or more visits were thought of as high use of health services. Regarding hospitalisation, any use (admission) was contrasted to no use.

Health needs factors

Health needs were measured by the following proxy variables: self-assessed health, comorbidity and health risks. Selfassessed health was measured by the Greek version of SF-12 which has been validated in a national representative general population sample in a previous study [START_REF] Kontodimopoulos | Validity of SF-12 summary scores in a Greek general population[END_REF]. With the SF-12 we assessed the physical and mental health of the respondents on a scale of 0-100, with higher scores reflecting better perceived physical and mental health. Comorbidity was based on the presence or not (and the number) of chronic diseases. Respondents were asked to report whether they suffered from at least one of the following thirteen chronic diseases: diabetes mellitus type I & II, hypertension, hyperlipideamia, heart failure, coronary ishaemic disease, irritable bowel syndrome, chronic bronchitis, asthma, osteoarthritis, Alzheimer's, depression and anxiety disorders. Chronic disease was a continuous variable ranging from 0 (no chronic disease) to 5 chronic diseases (the highest reported number).

Health risks, such as smoking and alcohol consumption, which are behaviours that stem from the individual's harmful lifestyle, which are believed to contribute to the development of illness and to the impairment of health. Participants were asked if they were smokers and they were classified as non-or daily/occasionally smokers. Information about alcohol consumption was based on the question "How many portions (e.g. a glass of wine) of alcoholic beverages on average do you consume per week?". Respondents were classified as consuming up to seven glasses of wine per week or consuming more. Finally, obesity is another independent variable which constitutes a contemporary disease associated with chronic diseases such as diabetes and cardiovascular disease, as well as health risks like physical inactivity and unhealthy nutrition. Obesity was assessed by the body mass index (BMI), and respondents were regarded as either normal (BMI<25), overweight (25≤BMI<30) or obese (BMI≥30).

Statistical Analysis

After the selection of the factors that possibly determine drug use and PP according to the literature, a chi-square test was used to assess whether prevalence of drug utilization and PP differed across socio-demographic characteristics.

Multivariable stepwise logistic regression analysis was conducted to determine the predictors of drug utilization. A logistic regression model, using forward Wald selection, was run and we used the exponentiation of B coefficient Exp(b) in order to estimate the adjusted odds ratio (OR) for each independent factor (socio-demographic, utilization of health care, health need proxies) with 95% confidence intervals. Multinomial logistic regression analysis using forward stepwise selection was further applied to analyze the impact of the independent variables on minor and major PP, with the reference category corresponding to those taking one drug. Results were considered statistically significant when p<0.05 and all analyses were performed using SPSS v17.0.

Oral informed consent was obtained from the participants before the interview. The study was approved by the ethics committee of the Hellenic Open University.

Results

Prevalence of drug use and polypharmacy

Four hundred one respondents (i.e. 41.6%) were drug users taking at least one drug every day. Approximately, 26% of the sample reported taking more than one drug while this proportion among drug users was 61.92%. Almost 28% of the sample had made more than four visits to a physician while 11.4% reported that had been hospitalized during the previous twelve months. The proportion of drug users increased with increasing age in both genders (χ 2 -test, p<0.0001) (fig. 1). Women used more medicines than men in each age group, but gender differences were statistically significant only in the older age groups of 55-64 and 65+ years old (p<0.01) with women having higher likelihood of using drugs (data not shown).

Figure 1. Drug use according to gender in each age group

The number of drugs taken, also increased with increasing age (χ 2 -test, p<0.0001) (fig. 2). Taking 1 or 2-3 drugs increased with age starting from the ages between 18-24, where taking one drug was the most common case, whereas taking four or more drugs occurred from the age group of 35-44 and increased rapidly with age, which was expected and confirmed that PP is associated with older age. Regarding the reported drugs (data not shown), anti-hyperntensives were the most common taken.

Figure 2. Number of drugs taken according to population age

Univariate analysis (table 2) showed that all the socio-demographic variables were significantly associated with drug utilization, while PP was associated only with age, marital status, education and employment status. Drug use was higher among women (χ 2 -test, p<0.01), older people (χ 2 -test, p<0.0001), married , (χ 2 -test, p<0.0001), those living in urban areas (χ 2 -test, p<0.05), those with primary education (χ 2 -test, p<0.0001) and the retired (χ 2 -test, p<0.0001), whereas older people (χ 2 -test, p<0.0001), those married (χ 2 -test, p<0.05), those with primary education (χ 2 -test, p<0.0001) and the retired (χ 2 -test, p<0.0001) were more prone to PP.

Drug use and polypharmacy

Logistic regression analysis (table 3) showed that female gender was associated with greater drug utilization but the results showed statistical insignificance (O.R.:0.8, CI:0.451-1.318) after adjusting for social and health need factors. Older people had a higher likelihood of using drugs. The predicted odds of people aged 65+ years old using drugs were almost twelve times the odds for young people aged 18-24 years old (OR: 11.6, CI:2.923-45.856). Remarkable differences in the magnitude of the odds ratio occur from the age group of 35-44, where these differences approximately were doubled or more as the age group increased. Education was associated with drug utilization, with highly educated individuals (university) being more than 2 times likely (OR: 2.3) to use at least one drug compared to those with primary education, after controlling for health needs and health services utilization. Furthermore, people who made more visits to a physician (4 times or more) during the past 12 months had a higher likelihood (OR:2.2) of taking a medicine. Regarding the need proxy variables, having at least one chronic disease was the strongest predictor with the odds ratio almost seven for being a drug user, with each increase in the number of chronic diseases. Those reporting better physical and mental health were 10% less likely to take medication (OR PCS =0.9, OR MCS =0.9). Employment status did not give statistically significant results, whereas marital status, urbanity and lifestyle characteristics were not associated with drug utilization, and thus were excluded from the model. All the independent variables explained 69.2% of the variability of the model, implying that they were the best predictors of drug use. Multinomial logistic regression analysis (table 4) -by assessing the odds ratio for minor or major PP-showed that in the case of minor PP the only significant predictors were age, comorbidity and physical health. Advanced age increased the odds of taking 2-3 drugs by a factor of 10% (in multinomial analysis age was used as continuous variable). Having at least one chronic disease (and for each increase) the odds of using 2-3 drugs increased 2 times (OR: 2.0, CI:1.109-3.776), whereas for each unit increase in physical health (PCS-12) the odds decreased by 10% (OR:0.9, CI:0.927-0.983).

Concerning major PP, with each increase in the number of chronic diseases, the odds of using 4+ drugs were increased almost ten times (OR: 9.6, CI:2.612-35.322), while with each unit increase in physical (PCS-12) and mental (MCS-12)

health, the odds of using 4+ drugs were decreased by 10%. Age was also a predictor, as with each year increase the odds of using 4+ drugs increased by 5.9%. More health care visits increased the probability of major PP by a factor of 10%.

Among lifestyle characteristics only smoking was significantly related to major PP with smokers being almost 3 times more likely to take 4+ drugs. Finally, obesity (bmi≥30) increased the probability of major PP by a factor of 3.8. Obese individuals were almost 4 times more likely to use 4+ drugs compared to individuals with normal weight. For categorical explanatory variables, the reference group for the calculation of the odds ratio (OR) is indicated in the parenthesis.

Discussion

The present study was conducted with a cross-sectional design using face-to-face interviews to collect information on drug utilization and PP in a representative sample of the Greek general population. It was undertaken in order to cover the absence of studies related to drug utilization and polypharmacy in Greece. This study adds new knowledge by examining the combined effect of various variables on drug use and especially on PP. Previous studies on medicine utilization in a multivariate framework in representative general populations are few [START_REF] Eggen | Pattern of drug use in a general population-prevalence and predicting factors: the Tomso study[END_REF][START_REF] Furu | Legal drug use in a general population: Association with gender, morbidity, health care utilization and lifestyle characteristics[END_REF][START_REF] Fillenbaum | Factors predicting change in prescription and non-prescription drug use in a community residing black and white elderly population[END_REF], and as far as we know, PP has not been studied in a multivariable framework. The results revealed a high rate of drug use and PP as well. Anti-hypertensives were the most commonly taken drugs since hypertension is the most common chronic disease, its prevalence is high [START_REF] Pitsavos | Epidemiology of cardiovascular risk factors in Greece: aims, design and baseline characteristics of the ATTICA study[END_REF] and there is a need for daily treatment.

A key finding of this study was that social disparities in medicine use exist in the Greek general population. Education was a strong predictor, with a higher educational level increasing the likelihood of using medicines after adjustment for health need and health service factors. This finding was not in accordance with previous studies which found a weak influence of education and an inverse association with medicine use [START_REF] Eggen | Pattern of drug use in a general population-prevalence and predicting factors: the Tomso study[END_REF][START_REF] Nielsen | Prescription and non-prescription medicine use in Denmark: association with socio-economic position[END_REF][START_REF] Fillenbaum | Factors predicting change in prescription and non-prescription drug use in a community residing black and white elderly population[END_REF]. The reduced use of medicines by less-educated individuals is a concern, since low education is related to poor health [START_REF] Pappa | Assessing the socio-economic and demographic impact on health related quality of life: evidence from Greece[END_REF] and therefore they are more vulnerable. A crucial question is why these differences still exist and whether these differences are due to the patients or to physician/health system characteristics. The reduced use may represent under-or inappropriate treatment for the less educated and may reflect poorer communication with physicians (since education influences attitudes and knowledge) or non compliance to doctors' advice. It is therefore of great importance to acquire more knowledge about the process leading to social inequalities in drug use in order to take the appropriate measures ensuring equal treatment for all individuals. Finally, our study did not confirm findings from previous studies [START_REF] Thomas | Polypharmacy among older men in South Wales[END_REF][START_REF] Haider | Analysis of the association between polypharmacy and socioeconomic position among elderly aged > or =77 years in Sweden[END_REF][START_REF] Haider | The influence of educational level on polypharmacy and inappropriate drug use: a register-based study of more than 600.000 older people[END_REF] about the relation between low educational level and PP.

The effect of health need, measured by morbidity and self-assessed health (i.e. physical and mental health), was significant as expected. Morbidity/comorbidity, physical and mental health were strong predictors of medicine use and PP. This is in accordance with results from previous studies [START_REF] Furu | Legal drug use in a general population: Association with gender, morbidity, health care utilization and lifestyle characteristics[END_REF][START_REF] Fillenbaum | Factors predicting change in prescription and non-prescription drug use in a community residing black and white elderly population[END_REF][START_REF] Thomas | Polypharmacy among older men in South Wales[END_REF][START_REF] Jyrrka | Patterns of drug use and factors associated with polypharmacy and excessive polypharmacy in elderly persons: results of the Kuopio 75+ study: a cross-sectional analysis[END_REF][START_REF] Rosholm | Relationship between drug use and self-reported health in elderly Danes[END_REF] and support findings that morbidity and selfassessed health are important determinants. It is reasonable to assume that people who rate their health as poor or using diagnosis reporting that they suffer from at least one chronic disease had a higher likelihood of using drugs or were more prone to PP in cases of severe illness or several diseases. An important viewpoint is that mental health is associated with major PP, and this is realistic since mental diseases are likely to be exposed to excess multiple drug treatment.

A large number of visits to a doctor, i.e. more than four times, within the last twelve months increased the likelihood of medicine use and major PP after adjustment for morbidity and self-assessed health. In our sample 40 % of those reported visiting a doctor had made more than four visits within the last year. This high health service utilization implies an enormous cost for the health care system, which constitutes a very important issue for Greece where the pharmaceutical expenditures have increased rapidly and impose a huge burden on health care budgets.

In agreement with previous studies we found that medicine use was more common among women than men and increased with increasing age [START_REF] Eggen | Pattern of drug use in a general population-prevalence and predicting factors: the Tomso study[END_REF][START_REF] Eggen | Patterns of medicine use in a general population (0-80). The influence of age, gender, diseases and place of residence on drug use in Norway[END_REF][START_REF] Furu | Legal drug use in a general population: Association with gender, morbidity, health care utilization and lifestyle characteristics[END_REF][START_REF] Fillenbaum | Factors predicting change in prescription and non-prescription drug use in a community residing black and white elderly population[END_REF][START_REF] Thomas | Polypharmacy among older men in South Wales[END_REF]. Multivariate analysis, after adjusting for other independent variables such as comorbidity and health service utilization, showed that gender differences were statistically insignificant. This indicates a weak effect of gender on drug use, with health need (comorbidity) and health service utilization as confounders in the association between gender and drug utilization. However, by analyzing gender differences according to age we observed that women were more likely than men to use medicines in the advanced age groups (data not shown) and the increased age-related morbidity is the most obvious explanation. PP is associated with increasing age, a finding that is common in previous studies and furthermore is confirmed by the fact that the majority of studies regarding PP focus the research on elderly populations.

Subsequently, our analysis found that BMI affected major PP. Association between obesity and drug use was found previously [START_REF] Bardel | Reported current use of prescription drugs and some of its determinants among 35 to 65 years old women in mid-Sweden: a population -based study[END_REF][START_REF] Thomas | Polypharmacy among older men in South Wales[END_REF]. It is reasonable to assume that a high bmi (≥30) is associated with higher drug use, as obesity was thought to be a contemporary disease which threatens peoples' health and their quality of life and is correlated with poor health and many chronic diseases such as diabetes, and on the other hand chronic diseases such as diabetes, cardiovascular diseases or depression may lead to physical inactivity and rising BMI. Furthermore, the relationship between obesity, PP and higher risk of hospitalization is of great importance to be studied further. In our study we found that risks such as smoking affected major PP, a finding that is in accordance with a previous study among old men [START_REF] Thomas | Polypharmacy among older men in South Wales[END_REF], whereas results from another previous study showed greater general drug use by smokers [START_REF] Eggen | Pattern of drug use in a general population-prevalence and predicting factors: the Tomso study[END_REF]. The relation between smoking and several severe diseases like cardiovascular diseases or cancer is the obvious explanation.

There are some limitations in our study. The sampling strategy focused on households, so a specific population having a greater need and higher utilization of drugs and of PP, such as institutionalized individuals were excluded. However, this strategy was followed by the majority of the health care utilization studies. Moreover, people reporting only OTC medicines were excluded from our analysis because they constituted a small group of 37 individuals. A larger sample of OTC users would permit us to separately analyze the utilization of the two different types of medicine and compare the results. As mentioned before, daily/regular use may exclude drugs taken occasionally and this could be a possible limitation of our study. There may be an underestimation of PP as daily/regular use left out occasionally taken drugs (sleep medication, analgesics etc), but in our study the portion of PP (minor and major) amounted to almost 62% of drug users. The high rate of reported PP minimizes the risk of underestimation and contributes to the quality of the data.

Methodological considerations

One of the most important methodological issues in investigating drug utilization through questionnaires is the recall period. As suggested in a previous study [START_REF] Bertoldi | A descriptive review of the methodologies used in household surveys on medicine utilization[END_REF] there is no consistency in the literature about the ideal recall period, while the prevalence of drug use is dependent on the recall period. Furthermore, another previous study [START_REF] Van Den Brandt | Comparison of questionnaire information and pharmacy data on drug use[END_REF] showed that the accuracy of recall of drugs taken, decreased with increasing age and the increasing number of medicines. In drug utilization studies the recall period varied from one [START_REF] Bardel | Reported current use of prescription drugs and some of its determinants among 35 to 65 years old women in mid-Sweden: a population -based study[END_REF][START_REF] Bekke | Self-reported drug utilization, health and lifestyle factors among 70-74 year old community dwelling individuals in Western Norway. The Hordaland Health Study (HUSK)[END_REF] to fourteen days [START_REF] Eggen | Pattern of drug use in a general population-prevalence and predicting factors: the Tomso study[END_REF][START_REF] Furu | Legal drug use in a general population: Association with gender, morbidity, health care utilization and lifestyle characteristics[END_REF].

In our study we asked respondents about daily (regular) use during the "current period", which was defined as the previous fourteen days. Since this study deals with daily use there may be minor problems with recall bias, minimizing the problem of remembering the drugs taken and their exact number, As it is validity of self-reported data composes a question in drug utilization studies. In this study we hypothesized that all drugs used were reported correctly by the interviewees and the high response rate (72.4) contributes to data quality and to the validity of the results.

Table 1 . Descriptive characteristics of health care use

 1

	Variables	N	%
	Total	968
	Medication Use
	Yes	401	41.6
	No	564	58.4
	Missing	3
	Medicine Number
	0	564	58.4
	1	153	15.9
	2-3	155	16.1
	4+	93	9.6
	Missing	3
	Number of visits
	0	297	31.6
	1-3	385	41.0
	4+	257	27.4
	Hospitalization
	Yes	109	11.4
	No	849	88.6
	Missing	10

Table 2 . Descriptive characteristics and socio-demographic differences in drugs utilization and polypharmacy (minor and major) Variables Drug use (n=401) Polypharmacy (n=248) Gender

 2

	Male	169 (42.1)	107 (43.1)
	Female	232 (57.9)	141 (56.9)
	sig*	p < 0.01	NS
	Age
	18-24	9 (2.2)	2 (0.8)

Table 3 . Multivariate logistic regression analysis results of drugs utilization

 3

	Variables	O.R.	95% CI	p-values
	Gender	0.8	0.451-1.318	NS
	(female)
	Age (18-24)
	25-34	0.9	0.313-3.008	NS
	35-44	1.2	0.380-4.158	NS
	45-54	2.4	0.725-8.004	NS
	55-64	5.9	1.686-19.989	<0.01
	65+	11.6	2.923-45.856	<0.001
	Education (primary)
	secondary	0.8	0.587-1.917	NS

Table 4 . Multinomial logistic regression analysis results for minor and major PP

 4

		Minor PP (n=155)			Major PP (n=93)
	Variables	O.R.	95% CI	p-value	O.R.	95% C.I.	p-value

  We appreciate the concern raised by the Reviewer, regarding the magnitude of reported odds ratios. In this study, the 41% OR of pharmaceutical consumption is indeed relatively high, however it is in accordance with the respective figures reported elsewhere and cited here (e.g. Eaggen 44.%, Del Rio et al. 45.3%, Bardel et al. 40%, Furu et al. 49%). Despite this relatively high OR, it still remains the least likely outcome, since the remaining 59% report being non-users. In our opinion, what is even more important here is the accuracy and precision of the regression estimates. Using a guideline provided by Hosmer and Lemeshow, authors of Applied Logistic Regression, one of the main resources for Logistic Regression, the minimum number of cases per independent variable is 10. In the present study eleven predictors were included in the regression, implying that approximately 110 outcomes (i.e. subjects using pharmaceuticals) -compared to 401 actually counted-would be sufficient to demonstrate this effect. To conclude, we (like the Reviewer) are also unaware of other analysis methods available to investigate this more reliably Hosmer, D. W., & Lemeshow, S.(2000). Applied Logistic Regression (2nd ed.). New York: John Wiley & Sons.

Comment [EP1]:


MD Athanasios Kotsakis

Sophia Agelaki

Nikolaos Vardakis

George Stathopoulos
email: georgsec@med.uoc.gr

Lambros Vamvakas

Antonia Kalykaki

Nikolaos Kentepozidis

Emmanouel Kontopodis

Georgia Sfakiotaki

Dimitris Mavroudis

Vassilis Georgoulias

A dose

published or not. The documents may come

Introduction

Lung cancer is the leading cause of cancer death in the United States and Europe and it has been estimated that more patients will die from lung cancer than prostate, breast and colorectal cancer together [START_REF] Jemal | Cancer Statistics[END_REF]. In 2006, lung cancer was in incidence the third most common cancer in Europe and the most frequent reason for death caused by a malignant tumor [START_REF] Longo-Sorbello | Role of pemetrexed in non-small cell lung cancer[END_REF]. Non-small cell lung cancer (NSCLC) accounts for approximately 80% of all lung cancers and has become the major cause of cancerrelated mortality in both men and women. Despite significant advances in the treatment of NSCLC over the past years, the prognosis of the patients with advanced or metastatic disease is poor with a median survival for the newly diagnosed stage IV patients ranging from 8-11 months and 5-7 months for those with relapsed disease [START_REF] Longo-Sorbello | Role of pemetrexed in non-small cell lung cancer[END_REF].

Platinum-based combination has emerged as the cornerstone first-line treatment for NSCLC. In two large meta-analyses, cisplatin-based combinations revealed superior responses and improved overall survival (OS) in some subgroups of patients [3;4]. Moreover, cisplatin has been shown to be superior to carboplatin when is combined with new chemotherapeutic agents (e.g. paclitaxel, docetaxel and gemcitabine) [START_REF] Hotta | Metaanalysis of randomized clinical trials comparing Cisplatin to Carboplatin in patients with advanced non-small-cell lung cancer[END_REF]. Recently, an antibody against vascular endothelial growth factor (bevacizumab) was proved effective in the first-line setting of non-squamous NSCLC, as significantly prolonged the progression-free survival (PFS) [5;6] and OS [START_REF] Sandler | Paclitaxel-carboplatin alone or with bevacizumab for non-small-cell lung cancer[END_REF].

Although these agents are active in NSCLC, they add toxicity which, in some cases, is severe. Nausea, vomiting, anemia, neuro-and nephro-toxicity comprise the most common occurred adverse events. Bevacizumab has also been associated with increased toxicity mainly, hypertension, proteinuria, hemorrhage and gastro-intestinal (GI) perforation.

Less toxic and more active regimens are required to be incorporated in the modern oncology armamentarium. Hence, the replacement of platinum compound with new agents has been emerged as an attractive approach for the treatment of NSCLC. Docetaxel promotes the assembly of microtubules from tubulin dimers, inhibits the depolymerization of tubulin which stabilizes microtubules in the cell and, eventually, inhibits DNA, RNA, and protein synthesis occurring mainly during the M phase of the cell cycle. On the basis of the results of big randomized trials [START_REF] Fossella | Randomized, multinational, phase III study of docetaxel plus platinum combinations versus vinorelbine plus cisplatin for advanced non-small-cell lung cancer: the TAX 326 study group[END_REF][START_REF] Shepherd | Prospective randomized trial of docetaxel versus best supportive care in patients with non-small-cell lung cancer previously treated with platinumbased chemotherapy[END_REF][START_REF] Fossella | Randomized phase III trial of docetaxel versus vinorelbine or ifosfamide in patients with advanced non-small-cell lung cancer previously treated with platinum-containing chemotherapy regimens. The TAX 320 Non-Small Cell Lung Cancer Study Group[END_REF], docetaxel has been approved as first-line treatment for NSCLC in combination with cisplatin and as monotherapy in the second-line setting. Docetaxel has shown activity in the first-line setting even with non-platinum combinations; we have previously shown that the docetaxel/cisplatin and the docetaxel/gemcitabine regimens had a comparable efficacy in terms of response rate (RR), PFS and OS with a more favorable toxicity profile for the non-platinum regimen [START_REF] Georgoulias | Platinum-based and non-platinumbased chemotherapy in advanced non-small-cell lung cancer: a randomised multicentre trial[END_REF].

Pemetrexed is a multitargeted antifolate drug that targets the enzymes thymidylate synthase (TS), dihydrofolate reductase (DHFR) and glycinamide ribonucleotide formyl transferase (GARFT) [START_REF] Adjei | Pemetrexed: a multitargeted antifolate agent with promising activity in solid tumors[END_REF]. By inhibition of these enzymes, it affects the synthesis of substrates necessary for cell growth and division and causes cell-cycle arrest in the S phase [12;13]. It has shown activity against NSCLC and has been approved as front-line treatment in combination with cisplatin as well as monotherapy in the second line setting for the non-squamous cell carcinomas [START_REF] Scagliotti | Cancer Institute of the United States, National Cancer Institute of Canada[END_REF]. In addition, pemetrexed given as maintenance treatment in NSCLC patients who achieve disease control after platinum-based front-line therapy could significantly improve OS and PFS [15].

The fact that both pemetrexed and docetaxel result to a cell-cycle arrest during different phases, may imply that they could have an additive or synergistic anti-tumor effect. Indeed, preclinical data have shown at least additive effect when pemetrexed was combined with docetaxel [16]. The same combination regimen has also been used in clinical trials in solid tumors with promising efficacy and acceptable toxicity. Furthermore, the combination of paclitaxel with pemetrexed was recently tested in patients with NSCLC with encouraging results [17]. These data provide us the rationale to conduct a dose-escalation study of the docetaxel/pemetrexed combination in order to determine the dose limiting toxicity (DLT) and the maximum tolerated doses (MTD) of the association in patients with advanced or metastatic NSCLC.

Patients and methods

Patient selection

Patients aged >18 years old with a pathologically or cytologically confirmed, unresectable locally advanced (stage IIIB with pleural infusion) or metastatic NSCLC who had received prior chemotherapy (maximum one prior chemotherapy regimen) as well as chemotherapy-naïve patients were eligible for the study; in addition, patients with CNS disease were also eligible if they had been irradiated and were clinically stable. Prior surgery or radiotherapy (to less than 25% of bone marrow) was allowed. However, a treatment-free interval of at least 4 weeks was required before study enrollment. Other inclusion criteria were: performance status 0-2 (ECOG); adequate blood counts (absolute neutrophil count›1,500/μL, hemoglobin <10/μL and platelets›100,000/μL); adequate renal function (serum creatinine‹2 mg/dL); adequate hepatic function (total bilirubin‹2 mg/dL and transaminases‹3 times the upper normal limit); adequate cardiac function without unstable angina or myocardial infarction within the last 6 months; no history of other primary cancer; and life expectancy of at least 3 months. All patients signed a written informed consent before study enrollment. The study had been approved by the Ethics and Scientific Committees of our Institution and is registered in ClinicalTrials.gov (NCT00684099).

Treatment

Treatment schedule and dose escalation are shown in Table 1. Docetaxel (Taxotere; Sanofi-Aventis, Bridgewater, USA) was administered as a 1 hour intravenous infusion (IV) at escalated doses from 60 to 85 mg/m 2 followed by pemetrexed (Alimta; Eli-Lilly, Indianapolis, USA) given as a 10 minutes IV infusion, at escalated doses from 400 to 550 mg/m 2 ; both drugs were given on day 1 every 3 weeks without prophylactic administration of hematopoietic growth factors. The treatment was continued for up to 6 cycles or occurrence of disease progression or unacceptable toxicity. All patients had standard vitamin supplementation with 1000 mcg vitamin B12 intramuscular every 9 weeks and folic acid 400 mcg/day per os for the administration of pemetrexed. In addition, standard premedication with corticosteroids for docetaxel administration was given. The used antiemetic regimen included ondansetron 16 mg intravenously 30 minutes before chemotherapy administration.

Dose escalation

The following dose-levels for docetaxel/pemetrexed have been evaluated: 65/400; 65/450; 70/450; 70/500; 75/500; 80/500; 80/550; 85/500 (mg/m 2 ) (Table 1). No intrapatient dose escalation was allowed. At least three patients were enrolled at each dose level. If a DLT was observed in one of the first three patients, then three additional patients were enrolled at the same dose level. DLTs were assessed during the first chemotherapy cycle. As DLT was defined the occurrence of any of the following: grade 4 neutropenia or thrombocytopenia; grade 3-4 neutropenia with fever >38.3 C, or a sustained temperature >38 C for more than one hour [18]; grade 3-4 nonhematologic toxicity; and any treatment delay because of toxicity. Dose escalation was discontinued and the DLT level would be reached if at least 50% of the patients treated at that level developed a DLT (e.g. at least two of three, or three of six patients). The MTD level was defined as the first level below the DLT dose level. At the MTD level, 20 additional patients have to be recruited (a total of 23 patients) in order to further evaluate the tolerance of the regimen at the recommended doses (RD level) for future phase II studies.

Toxicity assessment

Before each chemotherapy cycle, all patients had a detailed toxicity questionnaire and a physical examination in order to define treatment-related adverse events.

Hematologic toxicity was assessed weekly with complete blood counts (CBC) with differential and platelet counts; in case of grade III/IV hematologic toxicity, a CBC with differential and platelets count was performed daily until recovery (neutrophils>1500/μl and platelets>100.000/μl). A complete biochemical profile was performed at baseline and every three weeks thereafter. Toxicities were graded according to NCI CTC version 3.0. Day 1 treatment was administered on scheduled dates without any delay or dose reduction if the laboratory inclusion criteria were met; otherwise, day 1 treatment was postponed for up to 7 days until resolution of the prohibitive toxicity. Then, treatment was administered according to the predefined schedule and dose and without any missed dose. If the prohibitive toxicity had not resolved after a 7-day treatment delay, the scheduled treatment was missed and upon resolution of the toxicity, treatment was resumed as a new cycle using doses of the previous dose-level. Doses were also reduced to the previous dose-level in case of febrile neutropenia (grade II-IV neutropenia with fever > 38.0 0 C in two consecutive measurements at least one hour apart) [18] or grade III-IV thrombocytopenia with or without bleeding episode.

Tumor Response

Although patients were not required to have bidimensionally measurable disease to enter the study, response was assessed according to the standard RECIST criteria for those who did have [19]. Tumor response was assessed every three chemotherapy cycles by appropriate imaging studies and all responses have to be confirmed by a repeated imaging evaluation 4 weeks later. The duration of response was defined as the time from the day that objective tumor shrinkage was noted for the first time until the time of documented tumor progression or death due to any cause. The time to progressive (TTP) disease and the overall survival were defined as the time from the date of study enrollment until the date of progressive disease and the date of death due to any cause, respectively.

Results

Patients' demographics

Patients' characteristics are presented in Table 2. Between June 2005 and June 2009 a total of 62 patients were enrolled onto the study; forty-two patients were recruited onto the escalation part of the study and 20 at the RD level of the expanded part of the study. The patients' median age was 63 years and 87% of them had a performance status (ECOG) of 0-1. Fourteen (23%) patients suffering from a squamous cell carcinoma were enrolled in the trial before May 2008 when the published results demonstrated that pemetrexed was mainly active in patients with a non-squamous cell histology [START_REF] Scagliotti | Cancer Institute of the United States, National Cancer Institute of Canada[END_REF]. From the patients enrolled in the phase I part of the study, 33 (78.6%) had a non-squamous histology whereas in the phase II part of the study, 15 (75%) had a non-squamous histology. Fifty-one (82%) patients had stage IV disease and 21 (34%) were chemotherapy-naïve.

Compliance with the treatment

At the escalation part of the study, a total of 164 chemotherapy cycles were administered in all patients and in all dose-levels with a median of 3 cycles/ patient (range, [START_REF] Jemal | Cancer Statistics[END_REF][START_REF] Longo-Sorbello | Role of pemetrexed in non-small cell lung cancer[END_REF][START_REF] Hotta | Metaanalysis of randomized clinical trials comparing Cisplatin to Carboplatin in patients with advanced non-small-cell lung cancer[END_REF][START_REF] Ardizzoni | Cisplatin-versus carboplatin-based chemotherapy in first-line treatment of advanced non-small-cell lung cancer: an individual patient data meta-analysis[END_REF][START_REF] Sandler | Paclitaxel-carboplatin alone or with bevacizumab for non-small-cell lung cancer[END_REF][START_REF] Reck | Phase III trial of cisplatin plus gemcitabine with either placebo or bevacizumab as first-line therapy for nonsquamous non-small-cell lung cancer: AVAil[END_REF][START_REF] Fossella | Randomized, multinational, phase III study of docetaxel plus platinum combinations versus vinorelbine plus cisplatin for advanced non-small-cell lung cancer: the TAX 326 study group[END_REF][START_REF] Shepherd | Prospective randomized trial of docetaxel versus best supportive care in patients with non-small-cell lung cancer previously treated with platinumbased chemotherapy[END_REF][START_REF] Fossella | Randomized phase III trial of docetaxel versus vinorelbine or ifosfamide in patients with advanced non-small-cell lung cancer previously treated with platinum-containing chemotherapy regimens. The TAX 320 Non-Small Cell Lung Cancer Study Group[END_REF]. The median interval between cycles was 21 days (range, 21-33). Eleven (7%) cycles were delayed because of hematologic toxicity (n=2 cycles) as well as for reasons unrelated to the disease or treatment (n=9 cycles). Dose reduction was required in 8 (4.9%) cycles because of hematologic (n=6 cycles) and non-hematologic (n=2 cycles) toxicity. The reasons for treatment discontinuation were: completion of treatment as per protocol (n=12 patients), progressive disease (n=25 patients), toxicity (n=3 patients) and patient's consent withdrawn or lost to follow up (n=3 patients).

Regarding the expansion at the RD level, the rate and the severity of toxicity was similar to that observed during the escalation and significant delays or dose reductions were not required (data not shown).

Dose-limiting Toxicities

Table 1 shows the dose-escalation levels, the number of patients enrolled at each dose-level and the observed DLTs during the first cycle. The most common DLT was grade III-IV neutropenia or febrile neutropenia observed at dose-levels 2 (n=2 patients), 4 (n=2 patients), 6 (n=1 patient), 7 (n=1 patient) and 8 (n=2 patients). Other DLTs included grade IV thrombocytopenia at dose-level 3 (n=1 patient) and grade III generalized skin rash leading to treatment delay at dose level 6 (n=1 patient). The MTD has not been reached. However, dose escalation has been discontinued when it was ascertained that the regimen was safe, with an acceptable toxicity profile even at dose levels which exceeded the recommended single agent doses and it was observed that higher doses of the drugs were not associated with better efficacy results (see below). Therefore, the recommended doses for future studies are docetaxel 75mg/m2 and pemetrexed 500mg/m2 on day 1 every 3 weeks (5 th dose-level=RD level).

Hematologic and non-hematologic toxicity

Table 3 indicates the hematologic toxicity observed in all patients and in all chemotherapy cycles irrespectively of the dose-level. A total of 12 (6.7%) and 16 (9.1%) cycles were complicated with grade III and IV neutropenia, respectively; three patients presented grade III (n=2 patients) and IV (n=1 patient) thrombocytopenia; no bleeding episodes were observed and no platelet transfusions were required. There were four episodes of febrile neutropenia occurring at the 1 st , the 2 nd , the 5 th and the 6 th dose-levels but none of them occurred during the first chemotherapy cycle. There was no toxic death. One patient developed a non-neutropenic infection requiring hospitalization for intravenous antibiotics and cardio-respiratory support; the patient was uneventfully recovered.

Non-hematologic toxicity was generally mild. Table 4 shows the incidence of moderate to severe non-hematologic toxicity in all patients and all cycles, irrespectively of the dose-levels. The most common toxicity was asthenia which was grade II in 20 (12.2%) cycles corresponding to 11 (26%) patients and grade III in 3 (1.8%) cycles corresponding to three (7.2%) patients. Other toxicities were mild occurring in less than 5% of the administered cycles. Grade III generalized skin rash was observed in one (0.5%) patient two times. No other severe unexpected toxicities were observed. For the patients treated at the higher dose levels [START_REF] Reck | Phase III trial of cisplatin plus gemcitabine with either placebo or bevacizumab as first-line therapy for nonsquamous non-small-cell lung cancer: AVAil[END_REF][START_REF] Fossella | Randomized, multinational, phase III study of docetaxel plus platinum combinations versus vinorelbine plus cisplatin for advanced non-small-cell lung cancer: the TAX 326 study group[END_REF][START_REF] Shepherd | Prospective randomized trial of docetaxel versus best supportive care in patients with non-small-cell lung cancer previously treated with platinumbased chemotherapy[END_REF], the observed toxicity was slightly increased, mainly regarding the hematological profile. At the RD level, 20 additional patients were enrolled. The toxicity profile of the regimen as well as the incidence of different adverse events was, practically, similar to those observed during the dose escalation part of the trial. In particular, grade III and IV neutropenia occurred in three patients each, whereas febrile neutropenia was observed in one patient (Table 5).

Antitumor activity

In total, 61 patients were evaluable for response [41 out of 42 patients who were enrolled in the escalation part of the study and 20 patients enrolled in the RD level].One patient without a measurable target lesion was not evaluated for response.

Complete response (CR) was achieved in one (1.6%) patient and partial response (PR) in 13 (21.0%) [overall response rate [ORR]=23%; 95% C.I:12.4% -33.5%]; ten (16.1%) patients experienced stable disease (SD) and 37 (60.7%) progressive disease (PD). The disease control rate was 39%. The treatment was 1 st -line for five of the responders (ORR=25% in chemotherapy-naïve patients; 95% C.I: 6.0% -43.9%) and 2 nd -line for nine of them. (ORR=22%; 95% CI: 9.3% -34.6%) (p=0.790). In addition, four (28.5%) and 10 (21.3%) responses occurred in patients with squamous and nonsquamous cell carcinoma, respectively. The only CR was observed in the 8 th doselevel while the PRs were observed in all dose-levels (2 nd : n=1; 3 rd : n=2; 4 th : n=1; 7 th : n=2; 8 th : n=1) during the escalation part of the study. Regarding the efficacy of the combination in the expanded cohort of patients (n=20) who were treated with the recommended doses, a PR was achieved in six patients (30.0%), SD in four (20.0%) and PD in 10 (50.0%). The overall median response duration was 6.8 months (range, 0.5-16 months) and the overall median TTP 2.8 months (range, 0.5-17.2 months) [the median TTP was 2.8 (range, 0.7-17.2) and 3.3 (range, 0.4-13.1) months for chemotherapy-naïve and pre-treated patients, respectively (p=0.845)]. After a median follow up period of 18.5 months (0.7-38.2 months), the median overall survival (OS) was 10.0 months (range, 0.7-38.2 months); [the median OS was 10.4 (range, 1.4-38.2) and 9.2 (range, 0.7-31.5) months for patients treated in the 1 st -and 2 nd -line setting, respectively (p=0.356)]. The estimated 1-year survival rate for all patients was 40.5% (40.5% and 40.9% for chemotherapy-naïve and pre-treated patients, respectively).

Discussion

The necessity of more active and less toxic chemotherapy regimens for NSCLC patients is of great interest for the oncologists. In the present study, we combined two active drugs (pemetrexed and docetaxel) against NSCLC [7-9;14;20] in a doseescalation trial. It is interesting to note that the MTD has not been reached even at doses which exceeded the recommended doses for monotherapy with each one of them. Thus, given that efficacy results were similar in the high and low dose levels, we recommended the dose of 75 mg/m 2 for docetaxel and 500 mg/m 2 for pemetrexed (RD level) for future phase II studies.

The combination of pemetrexed with taxanes (paclitaxel and docetaxel) has been tested in phase I and II studies. The pemetrexed/paclitaxel regimen has been associated with encouraging efficacy results and acceptable toxicity even at doses which approached the recommended dose for each agent in the monotherapy setting [21;22]. In a phase II study, the combination of paclitaxel with pemetrexed, which was evaluated in chemotherapy-naïve patients with NSCLC, showed an encouraging efficacy with an objective response rate of 39.6% associated with a median survival of 14 months and a favorable toxicity profile [17].

There are few clinical trials evaluating the pemetrexed/docetaxel combination in patients with solid tumors [START_REF] Garland | Phase I dose escalation trial of biweekly pemetrexed in combination with docetaxel in advanced solid tumors[END_REF][START_REF] Petrylak | Phase I trial of pemetrexed (P) plus docetaxel (D) in advanced malignancies[END_REF][START_REF] Mackay | Phase I study of pemetrexed in combination with docetaxel in patients with advanced solid malignancies[END_REF][START_REF] Lopez-Martin | Phase I trial of the sequential administration of pemetrexed (P) and docetaxel (D) in patients (pts) with advanced solid tumours[END_REF]. In a phase I study, 17 patients with solid tumors were treated with a fixed dose of docetaxel (60mg/m 2 on day 8) combined with escalated doses of pemetrexed (300-600mg/m 2 on day1); the first level of 300mg/m 2 for pemetrexed and 60mg/m 2 for docetaxel was the MTD. Then, the investigators amended the treatment schedule and the same doses of pemetrexed were administered on day 1 and docetaxel on day 15. This sequential modified administration was feasible and well tolerated; at the time of study presentation, the MTD had not been reached (pemetrexed 600mg/m 2 and docetaxel 60mg/m 2 ). Hematologic toxicity was the main adverse event of the combination [START_REF] Lopez-Martin | Phase I trial of the sequential administration of pemetrexed (P) and docetaxel (D) in patients (pts) with advanced solid tumours[END_REF]. In another phase I study, both agents were administered on days 1 and 15. At the dose level of pemetrexed 400mg/m 2 and docetaxel 40 mg/m 2 the MTD had not been reached [START_REF] Garland | Phase I dose escalation trial of biweekly pemetrexed in combination with docetaxel in advanced solid tumors[END_REF]. Similar to our study, another phase I trial investigated the administration of pemetrexed and docetaxel on day 1 every 3 weeks, in patients with metastatic disease who had received ≥2 prior regimens of chemotherapy. This study was suspended and the planned phase II study was abandoned due to the limited tolerability and efficacy of this regimen [START_REF] Petrylak | Phase I trial of pemetrexed (P) plus docetaxel (D) in advanced malignancies[END_REF]. This is in overt contrast with the favorable toxicity profile which was observed in the current study; this discrepancy could be attributed to the fact that patients suffering from a wide range of tumors, which have a variable sensitivity to both agents, were enrolled in this trial. Based on the tolerability of the docetaxel/pemetrexed regimen it seems that both the biweekly as well as the 3-weekly schedule should be preferred for further evaluation.

In the present study, the docetaxel/pemetrexed regimen was well tolerated and neutropenia and fatigue were the most frequently observed adverse events. In the initial clinical trials, pemetrexed was associated with severe toxicity including hematologic toxicity, skin rash, lethargy, nausea and vomiting [START_REF] Rusthoven | Multitargeted antifolate LY231514 as first-line chemotherapy for patients with advanced non-small-cell lung cancer: A phase II study. National Cancer Institute of Canada Clinical Trials Group[END_REF][START_REF] Clarke | Phase II trial of pemetrexed disodium (ALIMTA, LY231514) in chemotherapy-naive patients with advanced non-small-cell lung cancer[END_REF][START_REF] Smit | ALIMTA (pemetrexed disodium) as second-line treatment of non-small-cell lung cancer: a phase II study[END_REF]. The incidence of these adverse events was significantly reduced with the administration of vitamin supplementation [START_REF] Bajetta | Phase II study of pemetrexed disodium (Alimta) administered with oral folic acid in patients with advanced gastric cancer[END_REF]. Consistently, the administration of vitamin B12 and folates was standard practice in the current study explaining, thus, the low incidence of severe toxicity.

Although efficacy was not the primary endpoint of the study, the pemetrexed/docetaxel regimen resulted in an ORR of almost 23%, a disease control rate (CR+PR+SD) of 39% and a median overall survival of 10.0 months. These efficacy results should be considered encouraging, given that 66% of the enrolled patients were already pre-treated. Moreover, it should be taken into account that the study was initiated in April 2005 and 23% of the enrolled patients had the diagnosis of squamous cell carcinoma, for which pemetrexed has been proved recently ineffective [START_REF] Scagliotti | Cancer Institute of the United States, National Cancer Institute of Canada[END_REF]; therefore, it could be argued that these particular patients could achieve the same clinical response with docetaxel alone.

In conclusion, this dose-escalation study demonstrated that the combination of docetaxel and pemetrexed is well-tolerated in patients with NSCLC. The drugs can be safely combined at the recommended, for each agent, monotherapy doses. The antitumor activity of this regimen was promising and its combination with antiangiogenic agents in non-squamous lung carcinoma could be of great interest in future studies. In addition, we consider that it merits further evaluation in second line treatment compared to monotherapy with docetaxel, pemetrexed or erlotinib.

  Park K, Patil S, Rolski J, Goksel T, de MF, Simms L, Sugarman KP, Gandara D (2008) Phase III study comparing cisplatin plus gemcitabine with cisplatin plus pemetrexed in chemotherapy-naive patients with advanced-stage nonsmall-cell lung cancer. J Clin Oncol 26: 3543-3551 15. Ciuleanu T, Brodowicz T, Zielinski C, Kim JH, Krzakowski M, Laack E, Wu YL, Bover I, Begbie S, Tzekova V, Cucevic B, Pereira JR, Yang SH, Madhavan J, Sugarman KP, Peterson P, John WJ, Krejcy K, Belani CP (2009) Maintenance pemetrexed plus best supportive care versus placebo plus best supportive care for non-small-cell lung cancer: a randomised, double-blind, phase 3 study. Lancet 374: 1432-1440 16. Teicher BA, Alvarez E, Liu P, Lu K, Menon K, Dempsey J, Schultz RM (1999) MTA (LY231514) in combination treatment regimens using human tumor xenografts and the EMT-6 murine mammary carcinoma. Semin Oncol 26: 55-62 17. Stathopoulos GP, Dimitroulis J, Toubis M, Katis C, Karaindros D, Stathopoulos J, Koutandos J (2007) Pemetrexed combined with paclitaxel in patients with advanced or metastatic non-small-cell lung cancer: a phase I-II trial. Lung Cancer 57: 66-71 18. Hughes WT, Armstrong D, Bodey GP, Bow EJ, Brown AE, Calandra T, Feld R, Pizzo PA, Rolston KV, Shenep JL, Young LS (2002) 2002 guidelines for the use of antimicrobial agents in neutropenic patients with cancer. Clin Infect Dis 34: 730-751 19. Therasse P, Arbuck SG, Eisenhauer EA, Wanders J, Kaplan RS, Rubinstein L, Verweij J, Van GM, van Oosterom AT, Christian MC, Gwyther SG (2000) New guidelines to evaluate the response to treatment in solid tumors. European Organization for Research and Treatment of Cancer, National

Table 2

 2

also indicates that 34 (54.8%) patients had previously received platinum-and 35 (56.5%) taxane-based chemotherapy.

(13.0) -2 (8.7) --

This work was partly supported by a research grant from the Cretan Association for Biomedical Research.

Conflict of interest

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