High mortality in lower salaried Norwegian men: the healthy worker effect?

STUDY OBJECTIVE This study aimed to examine whether the high mortality in lower salaried men in Norway was related to an inflow into this group of unskilled workers with high mortality. DESIGN Individual information on occupation was derived from the 1970 and the 1980 censuses and linked to mortality data for the period 1980-5 by the official, individual identification numbers. PARTICIPANTS The study population included Norwegian men aged 20-64 years in 1980. All men enumerated in the 1980 census (and who were registered in the 1970 census) within the two occupational groups, unskilled workers and lower salaried employees, were included. MEASUREMENTS AND MAIN RESULTS The subjects were allocated to the two occupational groups according to the official Norwegian classification of socioeconomic status. Mortality was measured by standardised mortality ratios (SMR). The findings suggest that a fairly large number of unskilled workers with high mortality move into the lower salaried employee group. This transition produces a higher SMR in lower salaried employees and, simultaneously, an artificially but modestly lower SMR in unskilled workers. The difference in SMR between the two groups is thereby exaggerated by 44%. The difference among the elderly was smaller. CONCLUSION Occupational mobility consistent with "the healthy worker effect" increases the SMR of lower salaried men and, at the same time, reduces slightly the SMR of unskilled workers.