C-reactive protein is associated with disability independently of vascular events: The Northern Manhattan Study

Background: high-sensitivity C-reactive protein (CRP) has been associated with cardiovascular events and mortality, but the association of CRP with functional status is not well defined. We hypothesised that serum levels of high-sensitivity CRP are associated with long-term trajectories of functional status independently of vascular risk factors and stroke and myocardial infarction (MI) occurring during follow-up. Design: prospective, population-based. Setting: northern Manhattan Study. Participants: stroke-free participants aged ≥40 years. Measurements: annual assessments of disability with the Barthel index (BI) for a median of 13 years. BI was analysed as a continuous variable (range 0-100). Baseline demographics, risk factors and laboratory studies were collected, including CRP (n = 2,240). Separate generalised estimating equation models estimated standardised associations between CRP and (i) baseline functional status and (ii) change in function over time, adjusting for demographics, vascular risk factors, social variables, cognition, and depression measured at baseline, and stroke and MI occurring during follow-up. Results: mean age was 69 (SD 10) years, 36% were male, 55% Hispanic, 75% hypertensive and 21% diabetic; 337 MIs and 369 first strokes occurred during follow-up. Mean CRP level was 5.24 mg/l (SD 8.86). logCRP was associated with baseline BI (-0.34 BI points per unit logCRP, 95% confidence interval -0.62, -0.06) but not with change over time. Conclusions: in this large population-based study, higher serum CRP levels were associated with higher baseline disability, even when adjusting for baseline covariates and stroke and MI occurring during follow-up. Systemic inflammation may contribute to disability independently of clinical vascular events.