USE OF MULTIPLE CAUSES OF DEATH IN THE ANALYSIS OF OCCUPATIONAL COHORTS - AN EXAMPLE FROM THE OIL INDUSTRY

Objectives-To examine the efficacy of routine examination of multiple causes of death occurring on death certificates in cohort studies, wit h an example from the oil industry. Methods-The underlying and multipl e causes were coded for all notified deaths from a cohort of 35 000 me n employed at eight oil refineries in the United Kingdom. Matrices of the frequencies of underlying causes by contributory causes were analy sed for the total population and by subgroups defined by refinery, occ upation, age, and calendar period of death. Results-Over 75% of the 10 128 certificates had two or more causes but this varied by disease. M any ratios of mentions of total to underlying causes were similar to t hose of England and Wales. Ratios for cancer of the larynx and pneumon ia were lower, indicating possible over-reporting of these diseases as the underlying cause. Investigation of an excess of pneumonia deaths at one refinery indicated possible miscoding of the underlying cause o r the wrong position of pneumonia on some certificates, particularly i n combination with malignancy and stroke. Conclusions-Routine analysis of multiple causes of death can provide useful additional information in cohort studies.