MISCLASSIFICATION RATES FOR CURRENT SMOKERS MISCLASSIFIED AS NONSMOKERS

Objectives. This paper provides misclassification rates for current ci garette smokers who report themselves as nonsmokers. Such rates are im portant in determining smoker misclassification bias in the estimation of relative risks in passive smoking studies. Methods. True smoking s tatus, either occasional or regular, was determined for individual cur rent smokers in 3 existing studies of nonsmokers by inspecting the cot inine levels of body fluids. The new data, combined with an approximat ely equal amount in the 1992 Environmental Protection Agency (EPA) rep ort on passive smoking and lung cancer, yielded misclassification rate s that not only had lower standard errors but also were stratified by sex and US minority/majority status. Results. The misclassification ra tes for the important category of female smokers misclassified as neve r smokers were, respectively, 0.8%, 6.0%, 2.8%, and 15.3% for majority regular, majority occasional, US minority regular, and US minority oc casional smokers. Misclassification rates for males were mostly somewh at higher. Conclusions. The new information supports EPA's conclusion that smoker misclassification bias is small. Also, investigators are a dvised to pay attention to minority/majority status of cohorts when co rrecting for smoker misclassification bias.