C-reactive protein, bone loss, fracture, and mortality in elderly women: a longitudinal study in the OPRA cohort

This longitudinal study investigates the association between C-reactive protein (CRP), osteoporosis, fractures, and mortality in 1044 elderly women. CRP was not an indicator for low bone mineral density (BMD), bone loss, or fracture in elderly women; however, women with elevated CRP levels over a prolonged period lost more bone over the 10-year follow-up, although fracture risk was not increased. Inflammation may contribute to the pathophysiology underlying impaired bone metabolism. This study investigates the association between CRP, BMD, bone loss, fracture risk, and mortality in women aged 75 and above. This longitudinal study is based on 1044 women, all age 75 at inclusion, reassessed at ages 80 and 85, with a mean follow-up time of 11.6 years (maximum 16.9 years). Women in the lowest CRP quartile (mean 0.63 mg/L) had lower BMD compared to those in the highest CRP quartile (mean 5.74 mg/L) at total hip (TH) (0.809 vs. 0.871 g/cm(2), p < 0.001) and femoral neck (FN) (0.737 vs. 0.778 g/cm(2), p = 0.007). A single measurement of CRP was not associated with bone loss; however, women with persistently elevated CRP, i.e., a parts per thousand yen3 mg/L at ages 75 and 80 had significantly higher bone loss compared to women with CRP < 3 mg/L (TH -0.125 vs. -0.085 g/cm(2), p = 0.018 and FN -0.127 vs. -0.078 g/cm(2), p = 0.005) during 10 years of follow-up. Women in the highest CRP quartile had a lower risk of osteoporotic fractures (hazard ratios (HR) 0.76 (95 % confidence intervals (CI) 0.52-0.98)) compared to those in the lowest, even after adjusting for weight and BMD. Mortality risk was only increased among women with the highest CRP levels. CRP was not an indicator for low BMD, bone loss, or fracture in elderly women in this study. Persistently elevated CRP however seemed to be detrimental to bone health and may be associated with a higher rate of bone loss. Only the highest CRP levels were associated with mortality.