Purpose: To compare the predictive validity of national guidelines for management of unstable angina, and to determine whether physician judgments have higher predictive validity beyond practice guidelines.
Method: Emergency-room patients presenting with non-traumatic chest pain/pressure (N=423) were classified as “low,” “intermediate,” or “high” cardiac risk for myocardial infarction (MI) or coronary artery disease (CAD) according to the American Heart Association/American College of Cardiology guidelines (1994, 2000, 2007). Physicians’ triage decisions (discharge/low risk, ward or monitored bed/medium risk, or cardiac intensive care/high risk) were assessed for guideline adherence and predictive validity of cardiac outcomes within 1 year. Sample was 51% female, mean age 52 (SD = 19); 73% White/Non-Hispanic, 18% Hispanic, and 9% other; 42% returned to the hospital for a cardiac procedure (e.g., percutaneous transluminal coronary angioplasty or coronary artery bypass graft) and/or received a cardiac diagnosis (e.g., acute MI, unstable angina, stable angina).
Result: Hierarchical logistic regression analyses were conducted entering demographics in block 1, each guideline seriatim in blocks 2-4, and physician assessment in block 5 as predictors; aggregate cardiac outcome (any procedure or cardiac diagnosis within one year) was the dependent measure. In the full model, age was a significant predictor (OR= 1.03, SE=.01,p<.01); 1994 guideline risk assessment was a significant predictor (OR=2.12, SE=.18, p<.001); physician assessment added unique variance for cardiac events (OR=3.42, SE=.21, p<.001). Results were similar for judgments of MI risk and CAD probability, and for procedures and diagnoses analyzed separately. Newer guidelines did not improve on older guidelines; indeed, they predicted outcomes less well.
Conclusion: Older guidelines demonstrated greater predictive validity than newer guidelines for cardiac outcomes, but physician assessment was overall the strongest predictor, controlling for all other factors. Results indicate that changes in guidelines should be empirically evaluated before widespread implementation. Further, implications for health care reform include a necessary role for physician assessment, in addition to the application of practice guidelines, in order to achieve quality of care.
Candidate for the Lee B. Lusted Student Prize Competition