Sickness absence: a review of performed studies with focused on levels of exposures and theories utilized.

Background: Despite the major impact sickness absence has on society, companies and individuals, surprisingly little scientific knowledge has been accumulated, and the studies that have been performed vary greatly.

Aim and method: Examination of about 320 studies of sickness absence regarding structural levels of exposures studied and theories utilized.

Results: Theories concerning sickness absence were found to vary greatly. Along with exposures and factors explaining sickness absence these theories were categorized with respect to different structural levels, i.e. they were deemed national, occupational, or individual. A classification of different types of absences is presented.

Conclusion: Although most of the reviewed studies were performed within the realm of medicine, only a few of the investigators used medical explanatory models or even considered the health status of individuals. Moreover, it is known that factors at "higher" structural levels have a substantial effect on sickness absence, but these were seldom taken into account, or even mentioned, in the reports scrutinized.