Physical illness leading to absence from work and the risk of subsequent suicide: a national register-based study

Background: Studies have shown that people with physical illness are at increased risk of suicide, but knowledge on the association between absence from work due to specific physical health problems and suicide risk is limited. This study aimed to examine the relationship between suicide risk and physical illness requiring leave from work across a range of specific physical diagnoses, and to study the interactions of mental illness and socioeconomic factors on this relationship. Methods: Using a nested case-control design, 9313 suicide cases and 169 235 matched controls were retrieved and interlinked from Norwegian national registries. Data on sick leave and related physical illness were derived from claims for sickness benefit and analyzed using conditional logistic regression. Results: For males, the risk of suicide increased progressively with the number of previous physical illness-related absences and the duration of recent physical illness-related absences. Absences related to digestive, musculoskeletal and neurological disorders as well as cancer and accidents/injuries were associated with a significantly increased risk of suicide. In contrast, females with a history of physical illness-related absence and a diagnosis of most organ or system specific illnesses were at a relatively reduced risk of suicide. In both genders, the suicide risk associated with physical illness resulting in absence from work differentiated significantly by history of sickness absence due to mental illness, and by education and income levels. Conclusions: The risk of suicide associated with physical illness requiring leave from work varied significantly by gender and by education and income status.