Life course determinants for early disability pension: a follow-up of Norwegian men and women born 1967-1976

Most studies on disability pension (DP) have focused on work conditions, socio-economic status and other contemporary factors. We wanted to study possible determinants of an early DP with a life course perspective within a large register-based cohort, with a main focus on the biological and social factors from childhood. We established a longitudinal, population-based cohort of all persons liveborn in Norway between 1967 and 1976. Through linkage between several national registers we obtained personal data on biological/health related as well as social background factors. After excluding persons who died, emigrated or were granted a DP before age 20 years (at which age follow-up started) and persons who did not become gainfully employed during the study period, the study population consisted of 595,393 persons. They were categorized into four strata according to gender and educational attainment. Adjusted hazard ratios (HR) for granting a DP until the end of 2003 and the corresponding population attributable risks (PAR) were computed. A total of 9,649 persons (1.6%) were granted a DP during follow-up. The disability risk was slightly higher among women than among men (1.7% vs. 1,5%). The following PARs were found: birth weight below the mean 5.7%, chronic childhood disease 6.8%, maternal marital status 4.4% and parental disability 8.8%. Low educational achievement was highly associated with DP, with a PAR more than twice as high as the overall PAR for the childhood factors. Early DP is associated with several biological and social background factors from childhood. It also shows a strong dependency on educational achievement.