The association between shift work and sick leave: a systematic review

Shift work is associated with a number of negative health outcomes, although it is not known whether it is associated with sick leave. This systematic review therefore aimed to determine whether an association exists between shift work and sick leave. A systematic literature search was conducted in six databases on observational studies. Two reviewers independently selected relevant articles and appraised methodological quality. Data extraction was performed independently by review couples. Articles were categorised according to shift work characteristics and summarised using a levels of evidence synthesis. In total, the search strategy yielded 1207 references, of which 24 studies met the inclusion criteria. Nine studies were appraised as high quality and used in the levels of evidence synthesis. Two high quality longitudinal studies found a positive association between fixed evening shifts and longer sick leave for female healthcare workers. The evidence was assessed as strong. Evidence was inconclusive for rotating shifts, shift work including nights, for fixed night work, and for 8-hour and 12-hour shifts. The association found between evening work and sick leave in female healthcare workers implies that the association between shift work and sick leave might be schedule and population specific. To study the association further, more high quality studies are necessary that assess and adjust for detailed shift work exposure.