High-sensitivity C-reactive protein and risk of nontraumatic fractures in the Bruneck study

Background: Chronic inflammatory diseases are associated with bone loss and an enhanced fracture risk. It is unknown, however, whether low-grade inflammation in healthy individuals, as estimated by the high-sensitivity C-reactive protein (hs-CRP) level, interferes with bone metabolism and affects the risk of nontraumatic fractures. Methods: Lifetime bone fractures were carefully recorded in the cohort of the population-based Bruneck Study (n=919) along with information on the date of occurrence and associated circumstances. The serum level of hs-CRP was measured from blood samples collected during the 1990 baseline examination and the 1995, 2000, and 2005 follow-up examinations. In addition, lifestyle and demographic characteristics, bone ultrasonographic data at the heel, and variables of bone metabolism were assessed. Results: Between September 1, 1990, and August 31, 2005, 69 subjects experienced nontraumatic hip or vertebral fractures. The incidence of nontraumatic fractures was 1.3, 3.8, and 13.9 per 1000 person-years in the tertile groups for hs-CRP. In multivariate pooled logistic regression analysis, the adjusted relative risk (95% confidence interval) of nontraumatic fracture in the highest vs lowest tertile group for hs-CRP was 9.4 (3.6-24.8) (P <.001). The exclusion of subjects with cardiovascular disease, dementia, malignancies, and chronic inflammatory disease had little effect on the results obtained. The hs-CRP level was unrelated to ultrasonographic measures of bone density, but showed an inverse relation to laboratory markers of bone turnover, like beta-crosslaps and osteocalcin concentration (P <.001). Conclusions: The hs-CRP level is a significant and independent risk predictor of nontraumatic fracture. This finding is consistent with the hypothesis of a tight interplay between low-grade inflammation and bone turnover.