C-reactive protein predicts incident fracture in community-dwelling elderly Japanese women: the Muramatsu study

Summary In a 6-year cohort study of 751 communitydwelling elderly Japanese women, we found that C-reactive protein (CRP) is a significant predictor of osteoporotic fracture in elderly Asian women, who have significantly lower CRP levels than Caucasians. Mechanisms explaining such an association should be further studied. Introduction While CRP, a systemic inflammation marker, is thought to be associated with osteoporosis, evidence supporting this claim has been limited. We aimed to assess the association between CRP levels and incident osteoporotic fracture in elderly women. Methods We conducted a cohort study with a follow-up period of 6 years. The study included 751 Japanese women aged 69 years or older. We measured serum high-sensitivity CRP (hs-CRP) levels as a major predictor. Covariates included age, body mass index, forearm bone mineral density, calcium intake, serum 25-hydroxyvitamin D, postural sway, osteoporosis medication, and physical activity. The primary outcome was incident limb and vertebral fractures. The Cox proportional hazards model was used to calculate the hazard ratio (HR) of fracture. Results Median hs-CRP values in study participants were 0.16 mg/L in the lowest tertile, 0.36 mg/L in the medium tertile, and 1.14 mg/L in the highest tertile. The hs-CRP values in these women were substantially lower than in their Caucasian counterparts. Limb or vertebral fractures occurred in 50 subjects during 4,250 person-years. Low CRP levels were associated with low incidence of limb or vertebral fractures (P for trend=0.035). The adjusted HRs of fracture for the medium and highest quartiles of hs-CRP levels, compared to the lowest quartile, were 2.22 (95% CI, 1.02–4.84) and 2.40 (95% CI, 1.10–5.24), respectively. Conclusions CRP is a significant predictor of osteoporotic fracture in elderly Asian women who have substantially lower CRP levels than Caucasians. Mechanisms explaining such an association should be further studied.