Patterns of mortality in a cohort of workers followed during 28 years: the Manresa study

INTRODUCTION AND OBJECTIVES: 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. SUBJECTS AND METHOD: 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. RESULTS: 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%). CONCLUSIONS: 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.