A cohort study on the relation between health status evaluated by occupational health surveillance and mortality

Abstract

Objectives To study the relation between the health status( healthy, fairly healthy, follow-up and abnormal) evaluated by Guangzhou occupational health surveillance(OHS) and the mortality. Methods Individual health records of 78 785 workers, aged≥35, from 399 factories were established by the Guangzhou OHS system in 1989～1992 as baseline informaiton. Prospective cohort study was used and the study was followed-up to 31 Dec, 1998. Chi-squared test and Cox regression model were used for data analysis. Results (1)This cohort of 78 785 workers were followed-up for 8 years,with a total of 627 635 person-years(389 240 person-years in men).1 525 deaths had occurred and the total mortality rate was 243.0 per 100 000 person-years(men:330.4,women:100.3). (2)46.1% of men workers and 34.4% of women workers had a history of occupational exposure, while 70.3 % and 1.5 % of men and women workers respectively had smoking history. (3)OHS health status was significantly related with total mortality in beth men and women. After adjusting for age, education, smoking and occupational exposure,using healthy and fairly healthy workers as the reference,the relative risks( RR ) for workers with follow-up and abnormal status were 1.85(95% CI 1.58～2.18) and 2.71(95% CI 2.39～3.08) in men,and 1.80 (95 % CI 1.22～2.64 ) and 2.89 (95 % CI 2.17～3.86) in women, respectively. Further analysis for neoplastic and cardio-cerebral vascular deaths showed similar relation with OHS status. (4)In men with follow-up or abnormal OHS status, the RR for cardio-cerebral vascular deaths was significantly greater in middle age(35～49) than in older age(50 ～59). Conclusion The workers' individual occupational health surveillance records provide readily available data for epidemiologic studies at low costs, and follow-up observation is possible. The occupational health surveillance status, being closely related with all deaths, is valuable to predict mortality. It is important to adopt early preventive health measures and clinical treatment to prevent early deaths from cardio-cerebral vascular diseases in middle-aged men. Key words: Occupational health surveillance; Death rate; Prospective cohort study