Association between C-reactive protein and hypertension in healthy middle-aged men and women

Objective: To ascertain whether C-reactive protein (CRP), an inflammatory marker related to increased cardiovascular risk, is associated with blood pressure in a sample of healthy, middle-aged people. Methods and results: A case-control study among 904 participants, 39-50 years old, from a cardiovascular risk screening study. Participants with systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥ 90 mmHg (n = 120) were considered as case participants and all others as control participants (n = 784). Exposure was defined using quintiles of high-sensitivity CRP among control participants. A continuous increase in blood pressure was observed across CRP quintiles. Systolic blood pressure increased 1.17 mmHg [95% confidence interval (CI), 0.60-1.74] and diastolic blood pressure 1.04 mmHg (95% CI, 0.64-1.45) from one quintile to the next. The prevalence of hypertension was 13.3% and it increased with CRP exposure: Q1, 8.9%; Q2, 11.9%; Q3, 12.2%; Q4, 14.3%; and Q5, 18.6%. After adjustment for sex, obesity, race, serum insulin level and family history of coronary heart disease, odds ratios for hypertension increased progressively across CRP quintiles. Participants in the highest CRP quintile were 2.35 times more likely to have hypertension than those in the lowest quintile (P = 0.03, trend test P = 0.04). Conclusion: These results are consistent with a continuous, independent association between serum CRP and elevated blood pressure.