Diagnosis and duration of sickness absence as predictors for disability pension: results from a three-year, multi-register based* and prospective study.

AIM: A study was undertaken to identify predictors for the transition from long-term sickness absence into disability pension with special emphasis on routinely collected medical information (e.g. diagnoses on sickness certificates) and the duration of sickness-absence spells.
METHODS: The study used a 10% random sample of the Norwegian population of working age (the KIRUT database). Individuals below 60 years of age, with spells of long-term sickness absence starting in 1990-91, where the medical diagnoses on the sickness certificates were known, were identified. This group (4,432 men and 5,645 women) was followed up for three years after the end of sickness absence with regard to disability pension and working status.
RESULTS: In logistic regression the following predictors significantly increased the risk of obtaining disability pension during the first three years after the long-term sickness spell: age, part-time employment, and duration of absence > 197 days. Higher education and having children < 11 years significantly decreased the risk. Having the medical diagnoses "mental problems" and diseases in the nervous system, respiratory system, and circulatory systems indicated high risk (compared with musculoskeletal disease). The diagnostic groups "pregnancy-related disease" and "injuries" implied low risk for disability pension. In separate regressions for both genders the "protective effect" of having small children remained only for women. High risk for sickness absence caused by "mental problems" reached significance only for men. CONCLUSIONS AND IMPLICATIONS: Several risk factors for transition from long-term sickness absence into disability pension were identified. The finding that spells of sickness absence with duration up to seven months did not imply increased risk of disability during the first three years may have implications for interventions aimed at long-term sickness absentees.