Objective To assess prevalence, in-hospital prognostic significance and angiographic correlation of C-reactive protein (CRP) elevation in patients with unstable angina.

Design Prospective observational study.

Setting Royal Hospital, Muscat, Oman.

Patients 100 patients admitted between July 2008 and January 2009.

Interventions Patients with unstable angina and ECG changes without biochemical evidence of necrosis (negative first troponin T), had CRP measured at admission by rate nephelometry (≥10 mg/l abnormal).

Main outcome measures In-hospital cardiac events and severity of coronary artery disease (CAD) in patients with and without CRP elevation.

Results 42% had CRP elevation ≥10 mg/l (Group I), and 58% had levels <10 mg/l (Group II). When compared with Group II, Group I patients had more anginal episodes (mean=4.6±2.5 episodes/patient vs 1.6±2.4; p<0.0001), myocardial infarction (58% vs 17%; p<0.01), in-hospital mortality (9% vs 0%; p=0.03) and severe triple vessel disease (71% vs 24%; p<0.01), and a higher total number of events (86% vs 24%; p<0.0001). Elevated admission CRP as a marker of in-hospital cardiac events showed a sensitivity of 72%, specificity of 88% and positive predictive value of 85%, and, as a marker of significant CAD, showed a specificity of 83% and a positive predictive value of 85%.

Conclusions Raised admission CRP level is predictive of increased in-hospital cardiac events and severe CAD in patients with unstable angina. CRP can be used to risk-stratify unstable angina patients independent of troponin levels. Patients with abnormal CRP should undergo coronary angiography either on-site or transferred to a centre with catheterisation facility during the index hospital admission.