Prognostic Value of C-Reactive Protein in Resistant Hypertension

Abstract

BACKGROUND: C-reactive protein (CRP) is a biomarker of systemic low-grade inflammation and a cardiovascular risk predictor in several clinical conditions. However, its prognostic value has never been examined in patients with resistant hypertension. METHODS: In a prospective study, 476 patients with resistant hypertension had CRP levels measured at baseline, together with other clinical laboratory variables, including ambulatory blood pressures (BPs). Primary end points were a composite of major fatal or nonfatal cardiovascular events, all-cause mortality, and cardiovascular mortality. Multiple Cox regression assessed the associations between CRP levels and end points. RESULTS: Median CRP was 3.8mg/l (interquartile range: 2.0-7.2mg/l). After a median follow-up of 9 years, 103 major cardiovascular events occurred, and 120 patients died, 62 from cardiovascular causes. Patients with CRP levels above the median value had a doubled excess risk of major cardiovascular events (95% confidence interval: 1.29-3.06; P = 0.002) and an 86% higher risk of cardiovascular death (95% confidence interval: 1.07-3.25; P = 0.029), after adjustments for potential confounders including traditional cardiovascular risk factors and ambulatory BP and dipping pattern. A high CRP equally predicted coronary (hazard ratio: 2.04; 95% confidence interval: 1.10-3.76; P = 0.023) and cerebrovascular events (hazard ratio: 2.72; 95% confidence interval: 1.30-5.67; P = 0.007). In interaction and sensitivity analyses, CRP levels were stronger predictors of worse cardiovascular outcomes in younger and obese patients, and in those with uncontrolled ambulatory BPs and with the nondipping pattern. CONCLUSIONS: In patients with resistant hypertension, elevated serum CRP levels is predictive of worse cardiovascular prognosis above and beyond other cardiovascular risk factors, including ambulatory BP levels and dipping patterns.