Role of diagnoses and socioeconomic status in mortality among disability pensioners in Norway—a population-based cohort study

Abstract

Several studies have shown increased mortality among disability pensioners. This study attempted to determine the causes of such an increase. A population-based study was carried out with 148,942 persons followed between 1990 and 1996 in Norway. Of this total, 6285 women and 4113 men [corrected] were on a disability pension at baseline. A Cox proportional hazards analysis was carried out separately for the women and men in which all-cause mortality was the outcome variable. Disability pension status, disability pension diagnosis, age, educational level, and mean annual income were entered as explanatory variables. Persons on a disability pension had a strongly increased mortality rate. The age-adjusted hazard ratio was 3.0 [95% confidence interval (95% CI) 2.4-3.8] for the women and 3.4 (95% CI 2.8-4.1) for the men on a disability pension, when they were compared with those not on a disability pension. When adjusted for education and income levels, the hazard ratios (HR) decreased significantly for the men, to 2.0 (95% CI 1.8-2.4), but not so for women (HR 2.5, 95% CI 2.2-2.9). Except for the men with musculoskeletal diagnoses, all of the diagnostic groups had hazard ratios above unity also after the adjustments were made. The study confirmed high early mortality among Norwegian disability pensioners in the period 1990-1996. The medical condition seemed to contribute more to the increased mortality among the women, whereas a low socioeconomic status was more important for the men.