Associations between C-reactive protein and all-cause mortality among oldest old adults in Chinese longevity areas: A community-based cohort study
Abstract Background: Higher C-reactive protein (CRP) levels have been proposed as a predictor of all-cause mortality in many existing studies from multiple populations, but the association for the oldest old adults (aged 80 and older) remains unclear. Objective: To examine the association between CRP and all-cause mortality among the oldest old Chinese adults. Design: This is a prospective, community-based longitudinal cohort study with 2206 adults aged 80 years old and older with available CRP test results. Cox proportional hazards regression models were used to estimate hazard ratios (HRs) with 95% confidential intervals (95% CIs) for all-cause mortality according to CRP quartiles, adjusting for potential confounders. Results: The median age of the participants was 93 years old, and the median CRP concentration was 1.13 mg/L at baseline. During a median follow-up period of 36.7 months, 1106 deaths were verified. After full adjustment for potential confounders, a high CRP concentration was positively associated with an increased risk of all-cause mortality. Compared with the lowest quartile, the fully adjusted HRs of the second, third, and fourth quartiles were 1.17 (95% CI: 0.94, 1.46), 1.28 (95% CI: 1.01, 1.61), and 1.50 (95% CI: 1.20, 1.87), respectively. The association of CRP with all-cause mortality was likely modified by smoking status (P = 0.011). Conclusions: Our study indicated that a high CRP concentration was likely to be a prospective factor predicting death among the oldest old adults. Future studies investigating additional factors of disease and aging processes are needed to obtain a better understanding of the mechanisms.