Factors associated with long-term sick leave in sick-listed employees: a systematic review

The objective of this systematic review was to investigate which factors are associated with continued sick leave among workers on sick leave for at least 6 weeks.

A systematic literature search was performed in Medline, EMBASE and PsycINFO, based on combinations of MeSH terms and free text words. Only cohort studies of workers on sick leave for more than 6 weeks at baseline were included. Outcome was measured in terms of factors related to long-term sick leave. The factors were classified first as predisposing, precipitating or perpetuating factors, and then as individual or work-related factors. Methodological quality was assessed for all studies and the strength of the evidence for each factor was assessed using the levels of evidence rating system.

Five cohort studies fulfilled all inclusion criteria and 77 factors were investigated. Of these, 16 different significant factors associated with long-term sick leave were identified and were all classified as predisposing factors. Evidence was found for 14 individual factors and two work-related factors. The level of evidence was found to be insufficient for all factors except older age and history of sick leave, which were found to have weak evidence.

Based on this review, there is weak evidence that older age and history of sickness absence are factors associated with long-term sick leave in sick-listed employees. There is insufficient evidence for an effect of other individual or work-related factors on long-term sick leave. There are no published studies on perpetuating factors related to long-term sick leave.