Purpose: To determine whether serum C-reactive protein levels, a sensitive indicator of inflammation, are associated with the risk of cardiovascular mortality among older women.
Methods: We conducted a case-cohort study within the Study of Osteoporotic Fractures, a population-based study involving 9,704 women aged > or = 65 years from four U.S. centers. We randomly selected 400 women from the entire cohort plus an additional random sample of 92 women from the 1,125 women in the cohort who had died during the first 6 years of follow-up. Baseline serum C-reactive protein levels were measured using a high-sensitivity immunoassay. Cause-specific mortality was ascertained by review of death certificates and hospitalization records. Multivariable Cox proportional hazards regression was used to determine the association between C-reactive protein levels and cardiovascular mortality.
Results: During 6 years of follow-up, 150 of the 492 women died, including 52 who died of cardiovascular disease. After adjusting for potential confounders, women with C-reactive protein levels in the highest quartile (>3.0 mg/L) had a 8.0-fold (95% confidence interval [CI]: 2.2 to 29) greater risk of cardiovascular mortality than those in the lowest quartile (< or = 1.0 mg/L). The association remained strong in women who did not smoke or take estrogen, and when early deaths were excluded. Women who smoked and whose C-reactive protein levels were above the first quartile had a very high risk of cardiovascular mortality (relative risk [RR] = 13; 95% CI: 3.4 to 47). C-reactive protein levels were not associated with noncardiovascular mortality (RR = 0.92; 95% CI: 0.4 to 2.1).
Conclusion: C-reactive protein level was an independent predictor of cardiovascular mortality in older women.