The 131st Annual Meeting (November 15-19, 2003) of APHA

The 131st Annual Meeting (November 15-19, 2003) of APHA

4262.0: Tuesday, November 18, 2003 - Board 6

Abstract #65561

Nondifferential exposure misclassification does not always lead to an underestimate of risk

Anne Jurek, MS, George Maldonado, PhD, and Timothy R. Church, PhD. Department of Environmental Health, School of Public Health, University of Minnesota, 420 Delaware St SE, MMC 807, Minneapolis, MN 55455, 612-623-3394,

Many investigators believe that nondifferential exposure misclassification inevitably leads to reduction in the strength of an exposure-disease association estimate. However, Sorahan and Gilthorpe (Occup Environ Med, 51, 1994, 839-40) and Thomas (Am J Epidemiol, 142, 1995, 782-3) showed that nondifferential exposure misclassification can spuriously increase the strength of a relative-risk estimate. In response to Thomas (1995), Weinberg et al. (Am J Epidemiol, 142, 1995, 784) suggested additional interesting results to be investigated. Here we present these additional results. In addition, we simulated a wider range of situations than did Sorahan and Gilthorpe (1994) or Thomas (1995). Using a binary exposure variable and various values for the true incidence proportion ratio (IPRT) and outcome occurrence rates, we generated from paired replicate data sets two estimates, one with exposure misclassified (IPRM) and one with exposure correctly classified (IPRC). For all situations we examined, random error alone caused departures away from the true value (IPRC > IPRT) in roughly half of the simulation trials, as expected. Except in the most extreme cases, a reversal from causative to protective (IPRM < 1) was observed in some of the trials. The percentage of simulations where IPRM was less than IPRT varied by the underlying IPRT value and misclassification rates. Contrary to the apparent belief of many investigators that IPRM is always less than IPRT in the face of nondifferential exposure misclassification, only in the most extreme cases does this hold true.

Learning Objectives:

Keywords: Epidemiology, Methodology

Presenting author's disclosure statement:
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.

Potpourri: Poster Session

The 131st Annual Meeting (November 15-19, 2003) of APHA