PERFORMANCE OF ODDS RATIOS OBTAINED WITH A JOB-EXPOSURE MATRIX AND INDIVIDUAL EXPOSURE ASSESSMENT WITH SPECIAL REFERENCE TO MISCLASSIFICATION ERRORS

Objectives Individual assessment of exposure by experts and the use of a job-exposure matrix are the two main methods of evaluating past occ upational exposures in community-based case-referent studies. The obje ctive of this study was to compare the performance of the estimations of the odds ratio in the two methods. This paper focuses on job-exposu re matrices whose entries consist of proportions of persons exposed. M ethods simulations were used to compare the variances of the estimatio ns of the odds ratios obtained with the two methods and to study the c onsequences with respect to bias and the precision of the odds ratios estimated for misclassifications of exposure produced by either the ex perts or the matrix. Results When there was no misclassification, the results showed that the precision obtained with the job exposure matri x was about three times less than that achieved by experts in a large range of practical situations. However, when potential errors of expos ure assessment were taken into account, the simulations suggested that the test of the hypothesis OR = 1 against the alternative OR not equa l 1 when exposure was assessed with an unbiased job-exposure matrix ha d a statistical power close to that obtained when exposure was assesse d by an expert with high sensibility and specificity. Conclusions The evaluation of exposure with an unbiased job-exposure matrix in studies of the association between exposure and disease had a statistical pow er close to that expected in practice with a good expert in the large range of practical situations which were investigated. Key terms case- referent studies, occupational exposure, simulation study.