Patterns of Mortality in a Cohort of Workers Followed During 28 Years: the Manresa Study

Abstract

To describe mortality patterns in a cohort of workers followed for 28 years, to estimate possible trends, and to compare the findings with those for the general population. The cohort included 1059 healthy male workers aged 30 to 59 years and followed for 28 years. Physical examinations and structured interviews were carried out every 5 years. Deaths were recorded from death certificates. The standardized mortality ratio (SMR) was calculated using sex- and age-specific mortality rates for the Catalan population as a reference for the same time period. The number of observed deaths in this cohort was 259 (24%). The main causes of death were cardiovascular diseases (n = 90, 35%) and cancer (n = 90, 35%). No excess mortality was observed in the cohort in comparison to the general population. All-cause mortality was lower, and cause-specific mortality was lower than or similar to rates in the general population. Overall, 382 deaths were expected, resulting in a significantly lower standardized mortality ratio of 67.7% (95% CI: 59.7%-76.5%). The patterns of mortality in this cohort of male workers were similar to those in the general population. Total mortality was lower than expected--evidence of the "healthy worker effect" which was particularly strong during the early part of the follow-up period.