C-reactive protein concentration and incident hypertension in young adults: the CARDIA study.

BACKGROUND: There is increasing evidence that C-reactive protein (CRP) concentration, a measure of inflammation, is an independent risk factor for the development of hypertension in older adults. However, it is unknown whether a similar relationship exists in younger individuals.
METHODS: The Coronary Artery Risk Development in Young Adults (CARDIA) study was initiated in 1985-1986 to determine the factors that are associated with coronary risk development in young adults. C-reactive protein concentrations were measured in 3919 African American and white men and women enrolled in CARDIA using blood specimens from the year 7 examination (1992-1993), when the age of the cohort was 25 to 37 years, and the year 15 examination (2000-2001).
RESULTS: In unadjusted analyses, CRP concentrations greater than 3 mg/L, compared with those less than 1 mg/L, was associated with a 79% greater risk of incident hypertension (odds ratio [OR], 1.79; 95% confidence interval [CI], 1.40-2.28). However, CRP concentration did not predict risk of incident hypertension after adjusting for year 7 body mass index (BMI) (OR, 1.14; 95% CI, 0.86-1.53) or year 7 BMI and other potential confounders (OR, 1.13; 95% CI, 0.83-1.52). In addition, year 7 CRP concentration was not associated with change in systolic or diastolic blood pressure after adjusting for BMI (P = .10 and P = .70, respectively). These findings were similar within each of the race- and sex-specific groups.
CONCLUSION: C-reactive protein is associated with hypertension in young adults, but in contrast to the finding in older populations, the association is no longer present after adjusting for BMI.