Predictors of atherosclerosis in the Honolulu Heart Program. II. Adjustment for autopsy bias.

Although autopsy is considered the final word on many medical questions, there has long been concern over possible bias in inference about a living population from analysis of autopsy material. Focus of the present paper is on the relationship between results obtainable only at autopsy and risk factors recorded as part of a prospective study of the entire "target population." Since pathologies are sure to be overrepresented in an autopsy sample compared to the target population, the dependence of autopsy scores upon risk factors may be distorted in the autopsy sample. The present paper proposes a method of adjustment for this bias. When both autopsy sample and target population can be stratified by major disease categories, under certain assumptions of equal effect, adjustment similar to the direct method for age adjustment may be applied. If, in addition, dependence can be characterized accurately by linear regression of both autopsy score and disease category frequency onto risk factors, then a very convenient calculation produces adjusted regression coefficients. This "parametric" method usually provides the most convenient results, with the greatest statistical power.