Nübling et al. BMC Public Health 2010, 10:428 http://www.biomedcentral.com/1471-2458/10/428 Performing the Study in Geriatric Care Invitations to participate in the study were made to n = 75 geriatric care facilities. These were facilities that had indicated to the BGW (Berufsgenossenschaft für Gesundheitsdienst und Wohlfahrtspflege/Institution for Statutory Accident Insurance and Prevention in Health and Welfare Services) in 2007 that they were interested in an employee survey. The BGW offered each of these institutions a free assessment of psychosocial factors at work with the COPSOQ questionnaire, including an evaluation of the facility specific results in comparison to the mean of all geriatric facilities and to reference values from the COPSOQ database. All in all, 36 geriatric care facilities accepted this offer; these addresses were given to the FFAS, which con- ducted the survey. The study was carried out in 2008 by the FFAS as an anonymous survey offered online and in a paper and pencil format. Participation was voluntary, no personal data like addresses were collected - therefore the study did not need to be approved by an ethics committee. Participants sent their filled-out questionnaires in a pre- stamped anonymous envelope directly to the FFAS; online data were transmitted using a protected internet connection. The FFAS analysed the data and sent reports to every participating institution with compari- sons of their results (average of all participants in the institution) compared to the overall mean in all institu- tions of the same type. Statistical analysis included descriptive statistics and comparison of mean COPSOQ-scale values using t-tests and Analysis of variance (ANOVA). Due to the high number of tests (22 scales plus 3 sin- gle items, 2 study groups, 2 reference values) and the relatively high number of subjects the significance level was established at p < 0.01 (two-tailed) for comparisons between the two study groups and the COPSOQ refer- ence values. Furthermore, an absolute difference of at least 5 points between the means was postulated as a relevant difference. COPSOQ scales have standard deviations (SD) of about 15-25 points, thus a difference of 5 points corresponds to an effect size of at least 0.2 which is considered as being the threshold of a small effect; for scales with smaller SDs the effect size is than 0.3-0.35 for a 5 point difference. For practicability rea- sons we decided to stay with the 5 points difference for all scales. Results Study Sample Altogether, 36 institutions took part in the survey: 20 of them were of the HC type, 16 were GNH facilities. The institutions varied greatly in size: the smallest had 15 employees, the largest 350. In total the questionnaire Page 4 of 12 was filled out by 889 employees, corresponding to a response rate of exactly one-third (33.33%), since 2667 employees had been asked to participate. The participa- tion rate varied greatly, however, from one institution to another: the lowest response rate ran to 11%, the highest to 93%. The subjects were grouped according to their occupa- tion: 412 persons are in the HC group (type of care = “mobile” and profession = “nursing or geriatric care pro- fession” according to the classification of professions, KbB92), 313 subjects form the GNH group (type of care = “stationary” and profession = “nursing or geriatric care profession”, again according to KdB92), and 164 of the 889 respondents are not active in nursing or geria- tric care occupations but in others occupations inside the geriatric care facilities such as administration, laun- dry, cleaning etc. As table 1 shows, the vast majority of those surveyed is female. This is true for the total population of the survey and particularly for the HC group. Furthermore, the older age groups are especially well represented in HC. Many of the study employees work part-time: 40% of the 889 study participants work 15 to 34 hours per week, and another 15% work fewer than 15 hours per week; in HC, almost 70% of the employees work part- time. With respect to specific types of shift, the results are differentiated according to the frequency of on-call duties, night shifts, shared shifts and alternating shifts in the past month. One-fourth of the participants served at least one on-call duty in the previous month; in HC the figure is as high as 40%, compared to only 16% in GNH. Around 15% of the respondents worked at least one night shift in the previous month; in HC, at 10%, the proportion is decidedly lower than the ger- iatric nursing home figure of 30%. 43% of those sur- veyed put in one or more shared shifts (two shifts or two parts of one shift during a day with free time between) in the previous month; here, again, the HC rate, at 70%, is much higher than the rate for GNH, which only runs to 26%. Almost half of the study population worked at least one alternating shift (rotat- ing schedule between morning, late or night shift); the HC rate of 47% is clearly lower than the geriatric nur- sing home rate of 65%. Psychosocial factors at Work For all 25 factors in the COPSOQ (19 aspects on the job situation and 6 outcome factors), internal comparisons between the employees in the two study groups GNH and HC and external comparisons to the overall mean of the COPSOQ database (all professions, N = 11168, as of 5/2008), and to the profession specific reference value