Independent Prognostic Value of Elevated C-Reactive Protein in Unstable Angina

Abstract

Background —There is growing evidence of the prognostic importance of C-reactive protein (CRP) in unstable angina. However, the independent value of CRP relative to other conventional markers at different stages of treatment has not been established. Therefore, we assessed the in-hospital and 90-day prognostic values of serum CRP in unstable angina. We also compared the relation of CRP at admission and discharge with 90-day outcome. Methods and Results —One hundred ninety-four consecutive patients were included in a derivation (n=105) and a validation set (n=89). Serum CRP was measured at admission, at 48 hours, and at hospital discharge. A cutoff point of 1.5 mg/dL for CRP provided optimum sensitivity and specificity for adverse outcome, based on the receiver operator curves. No association was found between CRP on admission and in-hospital outcome. CRP at admission, adjusted for age, ECG findings on admission, silent ischemia, left ventricular wall motion score, and high-risk clinical presentation, was related to the combined end point of refractory angina, myocardial infarction, or death at 90 days (hazard ratio [HR] 1.9, 95% CI 1.2 to 8.3, P =0.002). CRP at hospital discharge was the strongest independent marker of an adverse outcome (HR 3.16, 95% CI 2.0 to 5.2, P =0.0001). These results were confirmed in the validation set (CRP at discharge: HR 3.3, 95% CI 2.0 to 7.69, P =0.0001). Conclusions —In unstable angina, CRP is a strong independent marker of increased 90-day risk. Compared with CRP at admission, CRP at discharge is better related to later outcome and could be of great utility for risk stratification.