Letters Section Editor: Robert M. Golub, MD, Senior Editor.
To the Editor: Dr Peterson and colleagues1 evaluated the association between adherence to 9 American College of Cardiology/American Heart Association (ACC/AHA) class I guideline-recommended treatments and risk-adjusted in-hospital mortality. The study population included those patients with non–ST-segment elevation acute coronary syndrome in the CRUSADE (Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the ACC/AHA Guidelines) registry—a voluntary, self-reported, observational registry. The primary finding was that risk-adjusted in-hospital mortality was 6.31% for the lowest adherence quartile compared with 4.15% for the highest adherence quartile (P<.001). Observational registries are extremely useful for studying large populations or rare conditions. However, they are intrinsically limited by potential selection and reporting bias, confounders, and nonvalidated data, and hence best suited for generating hypotheses rather than proving causality.
Ting HH, Long KH. Hospital Performance and Acute Coronary Syndrome Outcomes. JAMA. 2006;296(11):1349-1350. doi:10.1001/jama.296.11.1349-a