BACKGROUND: Workplace adoption and reach of health promotion are important, but generally poorly reported. The aim of this study is therefore to evaluate the adoption of workplaces (organizational level) and reach of employees (individual level) of a multi-faceted workplace health promotion and work environment intervention targeting low back pain among nurses' aides in elderly care. METHODS: Percentage of adopters was calculated among eligible workplaces and differences between adopters and non-adopters were evaluated through workplace registrations and manager questionnaires from all eligible workplaces. From the adopted workplaces reach was calculated among eligible employees as the percentage who responded on a questionnaire. Responders were compared with non-responders using data from company registrations. Among responders, comparisons based on questionnaire data were performed between those consenting to participate in the intervention (consenters) and those not consenting to participate in the intervention (non-consenters). Comparisons were done using Student's t-test for the continuous variables, Fisher's exact test for dichotomous variables and the Pearson's chi(2) for categorical variables. Moreover odds ratios for non-responding and non-consenting were investigated with binary logistic regression analyses. RESULTS: The project was adopted by 44% of the offered workplaces. The main differences between adopters and non-adopters were that workplaces adopting the intervention had a more stable organization as well as a management with positive beliefs of the intervention's potential benefits. Of eligible employees, 71% responded on the questionnaire and 57% consented to participate. Non-responders and non-consenters did not differ from the responders and consenters on demographic factors and health. However, more non-responders and non-consenters were low skilled, worked less than 30 hours pr. week, and worked evening and nightshift compared to responders and consenters, respectively. Consenters had more musculoskeletal pain and reduced self-rated health, as well as higher physical exertion during work compared to non-consenters. CONCLUSIONS: Our recruitment effort yielded a population of consenters that was representative of the target population of nurses' aides with respect to demographic factors, and health. Moreover more consenters had problems like pain and high physical exertion during work, which fitted the scope of the intervention. TRIAL REGISTRATION: The study is registered as ISRCTN78113519.
B M C Medical Research Methodology, 2014, Vol 14, Issue 60