Referral to autopsy: effect of antemortem cardiovascular disease: a population-based study in Olmsted County, Minnesota.

PURPOSE: Autopsy studies can provide insight into disease trends and their determinants, including data on the prevalence of atherosclerosis. However, such studies are subject to autopsy bias, which limits their generalizability to the source population. The impact of this bias on autopsy based estimates of time trends in heart disease prevalence is unknown. To report on the trends over time in autopsy rates in Olmsted County, MN, to examine the association between clinical diagnoses of cardiovascular diseases (CVDs) and referral to autopsy and how this association may have changed over time. METHODS: We examined the trends in autopsy rates between 1979 and 1994 in Olmsted County, and the association between antemortem characteristics including cardiovascular diagnoses and autopsy referral. RESULTS: From 1979 to 1994, a total of 9110 residents died in Olmsted County. The average annual autopsy rate was 30%. Autopsy rates declined from 36% in 1979 to 23% in 1994, corresponding to an average decline of 0.6%/year (p < 0.01). Referral to autopsy was positively associated with younger age, male sex, in-hospital place of death, antemortem diagnoses of myocardial infarction (MI) or peripheral vascular disease (PVD), and earlier calendar period. There was no evidence of an interaction between calendar period and any of these predictor variables. Antemortem diagnosis of heart failure was associated with a decrease in the odds of referral to autopsy over time as compared to persons without such diagnosis. CONCLUSIONS: In Olmsted County, autopsy rates, although declining over time, have remained on average approximately 30%. Antemortem diagnoses of MI or PVD are associated with autopsy referral but this association did not change over time. While the greater decline overtime in the use of autopsy observed among decedents with an antemortem diagnosis of congestive heart failure (CHF) deserves further studies, the present findings reduce the concern for bias of time trends in the prevalence of atherosclerosis by changes in the clinical characteristics of decedents referred to autopsy.