Santos et al. BMC Public Health 2011, 11:60 http://www.biomedcentral.com/1471-2458/11/60 - First meeting: discussion concerning nutrition and avoiding obesity. - Second meeting: techniques for the control and reduction of stress. - Third meeting: hygiene and prevention of diseases. - Fourth meeting: the importance of adequate sleep and practices to reduce insomnia. - Fifth and sixth meetings: changing lifestyle and tips for a safe and healthy life. For both study groups, the themes discussed in the meetings were reinforced through the distribution of new didactic material three and five months after the end of the educational programs. Measurements Demographic and work-related data for all workers were obtained and recorded at entry into the study. The physical functioning domain measured by the Medical Outcomes Study Short Form 36 Health Survey (SF-36) was the primary outcome. This questionnaire is a gen- eral, widely used tool to evaluate QL, with eight scales: physical functioning, role physical, bodily pain, general health, vitality, social functioning, role emotional, mental health, and two summaries: the physical component and the mental component. The scales ranges from 0 (worst condition) up to 100 (best condition) [22]. The second- ary outcomes were the other domains of SF-36 and the work capacity evaluated by the Work Limitation Ques- tionnaire [WLQ]. WLQ is a tool with four scales: time management, physical demands, mental-interpersonal demands, output demands and a percentage index. The scales ranges from 0 (without limitation) up to 100 (limitations all the time) and it is possible to calculate a WLQ index using a table to define the loss of productiv- ity. For example a 5.0 WLQ index represents a 4.9% loss in productivity when compared with healthy people [23]. Both questionnaires, the SF-36 and WLQ were well designed and easy to administer, and validated for the Brazilian-Portuguese language [22,23]. The question- naires were self-administered before the interventions and five and 26 weeks after completion of the educa- tional programs. Sample size calculation Estimating that a difference of 10 points in variation of the physical functioning SF-36 score would be clinically relevant, and considering a standard deviation of 14.0 for this variation in both groups [24], 32 patients in each experimental group would provide 80.0% statistical power to detect a significant difference (P ≤ 0.05). How- ever, considering the possibility of loss to follow up of some individuals, a total of 101 employees underwent stratified randomization. Page 4 of 7 Ethical aspects After being invited to participate and accepting, workers signed a written informed consent before randomization. The study project was approved by the Research Ethics Committee of the Universidade Federal do Rio Grande do Sul (registration number: 2007755). The study was also registered at ClinicalTrials.gov (number NCT00874718). Statistical Methods The data were analyzed using Epi Info, version 6 and SPSS for Windows, version 14.0. Quantitative variables were graphically and statistically tested (with the Kolmogorov-Smirnov goodness-of-fit test) for normal- ity of distribution. Student’s t-test was used to evaluate differences in the primary and secondary outcomes. Other variables with a normal distribution were pre- sented as the mean ± SD, and the intra-group and inter-group comparisons were performed using paired and unpaired Student’s t-tests, respectively. Baseline non-normal quantitative variables were presented as the median (25th, 75th percentiles). A chi-square goodness-of-fit test was used to compare observed and expected frequencies of sick-leaves. A two-tailed P value less than or equal to 0.05 was considered statistically significant. Results Of 50 patients allocated to the intervention group, two did not fill in baseline questionnaires, one was trans- ferred to the night shift, and four were dismissed. Among the 51 patients allocated to control group, three did not fill in baseline questionnaires, one did not attend the educational meetings, and one was dis- missed. The demographic and work-related features of the subjects included in the analysis are presented in Table 1. Table 1 demonstrates that both groups had a similar distribution of age, gender, race, marital status, sector of job, medical condition, and current use of medications, body mass index, physical activity and years in work. The intervention group tended to have a higher median baseline physical functioning (table 1) and bodily pain score of SF-36 (median, percentiles 25-75: 72.0, 51.0-84.0 versus 61.5, 41.0-84 in controls; P = 0.043). Primary analysis At week 26 no significant differences in the variation of the physical functioning domain of the SF-36 were evi- dent: -1.49 in the intervention group and 0.92 in the control group, mean difference of -2.41 (95% confidence interval, -11.8, 2.32) (Table 2). The results remained comparable when clerical and production workers were analyzed separately.