Looking for Answers in All the Wrong Places

An old vaudeville story describes a man groping on all fours beneath a lamppost looking for a quarter he had dropped a block away. When asked his reason for searching there, he responded, because the light's better. The article by Jollis and colleagues [1] in this issue of Annals brings this story to mind. They and other members of the cardiology division at Duke University have for years prospectively accumulated a rich clinical database for managing patients with cardiovascular disease. Consequently, they were in a unique position to answer the Agency for Health Care Policy and Research's call of PORT (Patient Outcome Research Team) initiative to use the massive Medicare billing database to answer questions about effectiveness and outcome for patients with ischemic heart disease [2]. Their study shows, not surprisingly, that data sets completed for billing purposes and constructed mainly by financial experts differ substantially from those constructed by clinicians caring for patients.

Previous retrospective studies of the accuracy of claims data for the diagnosis of acute myocardial infarction found that clinical criteria were met in 43% to 80% of patients discharged with that diagnosis [3-6]. The Duke study extends these findings because it did not use retrospective chart review to validate the diagnosis but compared claims data with contemporaneously collected clinical data. In addition, the investigators were not constrained in identifying patients on the basis of claims data alone.

Their study involved 12 937 consecutive patients discharged between July 1985 and May 1990 with a procedure code for coronary arteriography. Lacking a third comparison group, they used the cardiology data set as the criterion or gold standard because it was likely to be more accurate. Although the assumption probably is correct, purists might give the claims data the benefit of the doubt by assigning accuracy whenever …