C-reactive protein implications in new-onset hypertension in a healthy population initially aged 65 years: the Proof study

BACKGROUND: Because inflammation is known to be related with several cardiovascular diseases, we sought to determine whether C-reactive protein (CRP) might precede the onset of hypertension. METHODS: The study population was selected from the Proof study cohort including 1011 individuals initially aged 65 years at baseline and followed for 7 years. CRP, ambulatory blood pressure measurement (ABPM) and casual blood pressure were repeatedly measured during examination. Normotensive individuals were selected according to different measurements of blood pressure, self-reported history of hypertension and use of antihypertensive treatment. RESULTS: Among 335 individuals, considered normotensive at baseline with ABPM (threshold 135/85 mmHg), with no history of hypertension and no use of antihypertensive treatment, the incidence of hypertension was 9.9% 2 years later. The 2-year risk for new-onset hypertension was 18% greater for 1 mg/l increment of CRP (odds ratio, 1.18; 95% confidence interval, 1.01-1.39). This relationship remained after adjustment for low-density lipoprotein cholesterol, BMI and change in CRP between the two examinations but not after adjustment for 24-h systolic ABPM. Among the 160 individuals considered normotensive at baseline with an additional criterion (casual blood pressure below 140/90 mmHg), the incidence of hypertension was 26.9% 2 years later. The 2-year risk for new-onset hypertension was 52% greater for 1 mg/l increment of CRP (odds ratio, 1.52; 95% confidence interval, 1.17-1.96) after adjustment for systolic ABPM, change in CRP and BMI. CONCLUSION: An elevated baseline CRP value precedes new-onset hypertension at an early stage among an elderly healthy population. Whether CRP measurement can ease the detection of patients likely to develop clinical hypertension remains to be determined.