Association is Not the Same as Accuracy

Dear Editor,

In a recent article, dos Santos et al. have concluded that, for patients with acute coronary syndromes, risk scores correlated with coronary artery disease severity. That apparently positive conclusion hides the poor performance of those scores to predict obstructive coronary artery disease due to two reasons. Firstly, in face of a diagnostic situation (presence of coronary artery disease ≥ 50%), the clinical focus should be on accuracy. Secondly, association (described in the article as correlation) does not ensure accuracy.

The major focus of that study should have been accuracy measures, such as area under the ROC curve, ranging from 0.56 to 0.70. Although statistically significant, those values indicate low accuracy from the diagnostic viewpoint. Corroborating those findings, in a recently published article in this same journal, our group has concluded that the degree of association (between scores and coronary anatomy) is not sufficient for risk scores to accurately predict the results of angiography.

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