Background and objective: C-reactive protein (CRP) is a widely used cardiovascular risk marker, but questions remain about its role in the disability process in old age. This study examines the associations between CRP levels and physical performance in old age in different societies.
Methods: data were collected during the baseline survey of IMIAS in 2012 in Kingston (Canada), Saint-Hyacinthe (Canada), Manizales (Colombia) and Natal (Brazil). Approximately 200 men and 200 women aged 65-74 were recruited at each site. CRP was assessed using a high sensitivity assay and categorised as low (<1 mg/l), moderate (1-3 mg/l), high (3-10 mg/l) and very high (≥10 mg/l). Participants were interviewed at home; blood pressure, weight and height were measured. Physical function was assessed with the Short Physical Performance Battery (SPPB) and hand grip strength. Data were analysed using descriptive statistics, bivariate analysis (χ²) and linear or logistic regression.
Results: CRP was significantly associated with low hand grip strength and poor physical performance in bivariate analyses. Hand grip strength association with CRP disappeared after adjustment by socioeconomic factors and health behaviours. The odds of poor physical function was OR = 2.67 [95% CI 1.43-4.99] comparing the highest and lowest CRP categories after adjustment by relevant covariates. The three SPPB components were assessed separately. Graded associations between low CRP and faster gait speed and shorter time to rise from a chair were observed in adjusted models. Association between impaired balance and CRP was attenuated after adjustment by relevant covariates, OR = 1.15 [0.65-2.04].
Conclusions: CRP could be a possible pathway from inflammation to physical decline in older populations.
Keywords: ageing; inflammation; muscle strength; older people; physical function.
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