Shift work and sick leave

Objective shift workers working nights are known to have higher morbidity f rom certain illnesses than day workers. This study examined episodes of cer tified sick leaves of day workers and shift workers in a large industrial p lant to examine whether slowly rotating shift work leads to increased risk of sick leave. Methods In a case-base design more than 11 000 episodes of sick leave, last ing more than 3 days, were obtained from the sick-leave files of a chemical plant in Norway. The diagnoses were grouped into 5 categories according to information on their work schedules. The workers included in the study wer e divided into 3 groups. They worked slowly rotating 3 shifts, 2 shifts wit hout night work, and daytime schedules. Results For all the diagnoses the shift workers and day workers were evenly distributed among the cases and the referents, the odds ratios ranging fro m 0.8 to 1.2. The risk of sick leave did not change with the number of year s in shift work. There was a higher risk of sick leave with musculoskeletal diagnoses among the 2-shift workers. Conclusions In this study shift workers did not have a higher risk of sick leave for diseases that, in previous studies, have been shown to be related to shift and night work. Although bias may be present in the study, the re sults are in line with those of previous studies, and they suggest that eve n certified sick leaves are not a valid proxy for morbidity.