MISCLASSIFICATION OF EXPOSURE IN CASE-CONTROL STUDIES - ASSESSMENT BYQUALITY INDEXES

Misclassification of a binary exposure in case control studies is usua lly assessed by sensitivity and specificity of the measured exposure. Sensitivity and specificity do not adequately measure the degree of mi sclassification because they assess only the proportion of truly expos ed (or unexposed) subjects who are misclassified by the defective meas urement. They do not account for the proportion of subjects, categoriz ed by the defective measurement as either exposed or unexposed, who ar e misclassified, in other words, the predictive value of misclassifica tion is by ''quality indices'' that take both of these criteria into a ccount and that are essentially rescaled sensitivity and specificity, or predictive value, measures. I present the relation between measured and actual odds ratios in terms of quality indices. If quality indice s are nondifferential or proportional, there is no misclassification b ias to the odds ratio. The relation offers a new approach to correctin g measured odds ratios.