Based on two criteria – recognition by the Colombian Association of Schools of Medicine 12 and listing in the International Medical School Directory 13- 10 medical schools in Bogotá were invited to participate in this cross-sectional study carried out during 2006. Participation was encouraged by offering school-specific data (without student identifiers) to school investigators, relevant literature reviews and a short course on healthy lifestyle counseling to local study coordinators, and the chance to win a heart rate monitor for participating students in each school. Eight schools were selected based on a clearly expressed intention to participate and provision of the necessary conditions for survey administration. All first- and fifth-year medical students from these schools were invited to participate in a self-reported survey of personal health behaviors and attitudes toward medical practice. A total of 661 students completed the survey, a response rate of 76% for first-year and 79% for fifth-year students.

The Healthy Doctor = Healthy Patient Questionnaire, already used for a representative sample of U.S. medical schools 1014, was translated, back-translated and culturally adapted for its use in Colombian medical schools. Dr Frank, principal investigator of the original project participated in this process to ensure questionnaire integrity and cross-country comparability. IRB approval was obtained from the Universidad de los Andes and the Fundación Santa Fe Ethical Committees.

Prior to survey administration, semi-mandatory classes and workshops explained participant anonymity, confidentiality, and the voluntary nature of participation. After the study coordinators read a 10-minute standardized script containing general instructions, the survey was administered using an electronic (Web) platform that prevented unanswered items. Completion time was on average 30 minutes.

The five sections of the questionnaire asked about the following: (i) height, weight, general health status, and family history of chronic diseases; (ii) personal habits in nutrition, physical activity, smoking, and alcohol consumption; (ii) perceptions of preventive medicine training and medical school environment; (iv) attitudes toward preventive counseling; and (v) basic knowledge (30 questions total) on smoking, alcohol use, nutrition, and physical activity. Knowledge questions in each specific area were drawn from the following sources: current recommendations for nutrition and daily energy requirements, 415; health benefits and prescription of physical activity, 16; the health effects and classification of tobacco exposure 17; and the health effects of alcohol use and drinking status classification 1518.

Outcome measures and independent variables were selected based on previous investigations of correlates of medical students' prevention counseling practices 10 and the specifics of medical training and practice in Colombia and the Latin-American region 19.

Our primary outcome, student attitudes toward preventive counseling on healthy lifestyles, was assessed by asking "how relevant do you think this will be in your intended practice – talking to patients about physical activity, nutrition, smoking, alcohol use, weight management". Students reporting "highly" were considered to have a positive attitude toward always counseling patients on each specific habit; those reporting "somewhat" or "not at all" were classified as not having a positive attitude toward preventive counseling.

Student reports of personal habits were considered the primary independent variables. Compliance with international physical activity recommendations (≥ 150 min/week of moderate-to-vigorous physical activity) 20 was assessed by inquiring the average duration of vigorous and moderate physical activities in the past week. Compliance with international recommendations for fruit and/or vegetable consumption (≥ 5 servings per day) 21 was assessed using a validated food frequency tool. Students reporting current use of tobacco and having smoked ≥ 100 cigarettes during their lives were considered smokers 22. Students reporting consumption of ≥ 5 drinks of alcohol on a single occasion in the past month were considered binge drinkers. Women reporting an average consumption of >1 daily drink or men an average of >2 daily drinks in the past month were considered heavy drinkers 1518 Students meeting physical activity, and fruit and vegetable recommendations, who were also non-smokers and neither heavy nor binge drinkers were considered to have overall healthy habits.

Covariates included other factors associated with medical training. Students were designated to have a perception that their medical school encourages healthy behaviors on each individual habit and promotes health in this area ("My medical school encourages their students to be physically active, to eat healthily and discourages smoking and alcohol drinking"), and to have a perception that they received adequate training on this area were based on responses to the question ("How much training have you had on the topics of nutrition, exercise/physical activity, smoking cessation and alcohol?"). Adequate knowledge on each area (physical activity, nutrition, alcohol consumption and smoking) was defined as having at least 60% correct answers on each group of questions in order to objectively assess students' basic knowledge and competency on each habit.

We anticipated a priori that student understanding of and attitude toward counseling and medical training-related factors could be affected by clinical experience and time in the medical school environment, respectively. Because the two groups (first- and fifth-year students) were very distinct, analysis of these variables was stratified by year of training (no data were pooled). After first estimating the prevalence of reported healthy habits, weight status, attitude toward preventive counseling and perception of school environment, we compared the prevalence estimates for the two groups using chi-square tests. Second, we used logistic regression analysis to assess the association between overall healthy habits (physical activity, nutrition, weight control, smoking, alcohol use) and student attitudes toward preventive counseling on these issues, stratified by year of training. Third, to assess effect modification, we further stratified the analysis, only among fifth-year students, by medical training-related factors, including basic knowledge about each healthy habit, perception of the school's promotion of each healthy habit, and perceived adequacy of training on each healthy habit. Finally, we used multivariate models, adjusted for gender and the medical training-related factors, to assess the association between fifth-year students' personal practices on each habit and their attitudes toward preventive counseling. Collinearity between independent variables was evaluated using regression diagnostic tests. All analyses were conducted using SAS v 9.123.

The median age and percentage of females for the first and fifth-year students were 21 years and 59.5% and 25 years and 65% respectively, with over 93% of students reporting middle and high socioeconomic status. For both groups, we found low compliance with the recommendations on fruit and vegetable consumption and physical activity, and a high prevalence of binge drinking (Table 1). Compared to first-year students, the proportion of non-smokers and non-binge drinkers/abstainers was lower among fifth-year students (83% vs. 75%; p = 0.023 and 57% vs. 42%; p = 0.002, respectively). Most students (≥ 78%) in both years had a favorable attitude toward preventive counseling on individual habits, but the proportion of positive attitude toward physical activity counseling was higher for fifth- than first-year students (91% vs. 85%; p = 0.016). Additionally, the proportion of students perceiving school promotion of each healthy habit was lower among fifth- than among first-year students for nutrition, physical activity, and alcohol consumption.

Among first-year students, non-binge drinkers were more likely to have a positive attitude toward counseling patients about alcohol use (OR 1.79; 95% CI 1.12–2.87) than binge drinkers (Additional file 1). Among fifth-year students, we found positive associations between compliance with nutritional recommendations, being a non-smoker, and not being a binge-drinker with a positive attitude toward counseling on nutrition, smoking and alcohol use, respectively. In addition, fifth-year students complying with the nutritional recommendation were much more likely to have a positive attitude toward counseling patients about weight control (OR 10.25; 95% CI 1.13–79.19) (Additional file 1). We found no evidence that medical training-related variables for each health-related habit (basic knowledge, student perception of school's promotion of a healthy environment, perception of adequate training) acted as effect modifiers of the association between fifth-year students personal habits and attitude toward counseling on each corresponding healthy habit (data not shown).

Finally, the multivariate logistic regression analyses showed that after controlling for gender and medical training-related factors, consumption of ≥ 5 daily servings of fruits and/or vegetables, not being a smoker or binge drinker were associated with a positive attitude toward counseling on nutrition (OR = 4.71; CI = 1.6–14.1; p = 0.006), smoking (OR = 2.62; CI = 1.1–5.9; p = 0.022), and alcohol consumption (OR = 2.61; CI = 1.3–5.4; p = 0.009), respectively (Additional file 2).

The study limitations include its cross-sectional nature and the possibility of self-report biases; however, the questions related to lifestyle habits were extracted from recognized epidemiological surveillance tools 31, which in turn enabled comparisons with national estimates for these habits. However, since the study was limited to students attending mostly private medical schools in Bogotá, extrapolation of these results to students attending public schools or in other regions should be performed cautiously.

The study's strengths include a high response rate, the availability of objective data on knowledge about healthy habits, and the use of the extensively tested Healthy Doctor = Healthy Patient questionnaire whose primary outcome measure of self-reported counseling rates has been objectively validated 32. Future research including intervention studies in developing countries that demonstrate the effectiveness of healthy behavior promotion among medical students for improving attitudes towards and delivery of preventive counseling are warranted and will help bridge the gap between medical students' behaviors and related attitudes towards counseling and physicians' preventive practices.