The influence of exposure and observed mortality definitions when estimating lung cancer attributable mortality to...

The estimation of attributable mortality to secondhand smoke (SHS) exposure depends on the conceptual framework used. This framework encompasses the population group considered for observed mortality (nonsmokers, never smokers, or the entire population) and whether the exposure prevalence takes into account the exposure setting. This study assesses the impact of variations in this conceptual framework on estimates of attributable mortality to SHS exposure.

A simulation study of lung cancer attributable mortality to SHS exposure was performed. Five approaches for handling observed mortality were considered in three exposed populations (never smokers, nonsmokers, and the entire population) and three exposure settings (indoor settings, home and workplace). Data on observed mortality (Spanish National Institute of Statistics), prevalence of both SHS exposure and tobacco use (both derived from a nationally representative survey) for the Spanish population aged 16 and over were used. Attributable mortality to SHS exposure was estimated based on the assumptions of each of the five observed mortality approaches.

Among 22,827 observed lung cancer deaths, mortality among never smokers ranged from 3503 to 6873 depending on the approach, and was 5322 among nonsmokers. Across approaches, mortality attributed to SHS exposure differed by up to 4.8 times for never smokers in indoor settings, and up to 4.5 times for nonsmokers in the work.

The lack of consensus in the conceptual framework used to estimate the attributable mortality to SHS exposure results in differences in the estimated attributable mortality burden. Comparisons of attributed deaths should not be made without first reviewing the definitions of the indicators and the assumptions adopted in the estimation process. Having common definitions would facilitate comparisons between estimates.