Smoking as a contributing cause of death in Wisconsin, United States, 1990

Objective: To investigate the frequency of smoking as a listed cause of death for selected lung diseases on death certificates. Design and setting: Population-based descriptive and case-control study. Deaths, next of kin, and certifying physicians were identified from the state death certificate database. Smoking history of the decedents was ascertained through a questionnaire mailed to the next of kin. Participants: All deaths from smoking-related lung diseases in Wisconsin in 1990. In the case-control study, cases were defined as deaths in which death certificates listed smoking as a contributing cause of death. Controls were defined as deaths in which smoking was not mentioned on the death certificates. Main outcome measure: Presence of the ICD-9 code 305.1 (tobacco use disorder) on a death certificate. Results: While epidemiologic evidence indicates that smoking contributed to 80% of these deaths, it was mentioned as a contributing cause of death in only 263 (7%) of the 3866 certificates examined. Females, rural residents, and more educated persons were more likely to have smoking listed as a cause of death. Older physicians and oncologists were less likely to list smoking as a cause of death. The case-control study showed that among controls (whose certificate did not mention smoking), almost half were heavy life-time smokers and more than one-third were smokers at the time of death. Conclusions: Physicians infrequently listed smoking on the death certificate, even when smoking was likely to have contributed to the death. A more accurate recording of smoking as a cause of death would improve the usefulness of death certificates for epidemiologic research and public health practice.