Predictive value of C-reactive protein for progression from prehypertension to hypertension: a prospective cohort study based on the CHARLS database

Abstract

Abstract Background The key to preventing and treating hypertension is predicting the progression of prehypertension and implementing preventive and control measures. Whether C-reactive protein (CRP) can predict the progression from prehypertension to hypertension remains to be confirmed. Methods Based on prospective data from CHARLS from 2011 to 2015, 1,236 middle-aged and elderly individuals with prehypertension were enrolled and stratified into three groups according to their baseline CRP levels using predefined CRP categories. We employed interval-censored Cox models and restricted cubic spline analysis to assess the association between CRP level and hypertension risk, as well as model improvement metrics after incorporating CRP. Results During the 4-year follow-up period, 269 participants developed incident hypertension, accounting for 21.8% of the study population. In the adjusted interval-censored Cox model, higher log-transformed CRP was associated with a higher risk of hypertension (HR = 1.34; 95% CI: 1.07–1.68). Because the restricted cubic spline analysis suggested a nonlinear pattern (P for nonlinearity = 0.040), this estimate should be interpreted as an overall summary rather than a constant risk increase across the full CRP range. In the analysis based on clinical CRP categories, participants with CRP > 3 mg/L had a higher risk than those with CRP < 1 mg/L (HR = 1.61; 95% CI: 1.15–2.26). Subgroup analyses showed no significant interactions across age, sex, BMI, systolic blood pressure, or remnant cholesterol groups. After adding CRP to the conventional risk model, the C-index increased from 0.626 to 0.634. Conclusions Elevated CRP levels were associated with the progression from prehypertension to hypertension among middle-aged and elderly adults. Adding CRP to conventional risk factors provided modest additional predictive information. CRP may serve as a supplementary indicator for identifying individuals who need closer follow-up, but it should not be used alone for risk assessment.