Nashville, Tenn – Providing evidence of a role for inflammation in osteoporosis, Australian investigators have found that circulating levels of C-reactive protein (CRP) independently predict fracture risk in postmenopausal women. The findings were reported here at the 27^th Annual Meeting of the American Society for Bone and Mineral Research.

As measured by high-sensitivity assay, a CRP level of 4.9 mg/L or higher was associated with a 60% increased fracture risk compared with lower levels of the proinflammatory protein, the study found. Patients with a combination of high CRP levels and low bone mineral density (T-score <e;2.5) had a ninefold increased risk of fracture compared with those with lower CRP levels and normal bone density.

"Increasing data suggest that reactive oxygen species are involved in osteoclastogenesis and the bone resorption process, leading to the hypothesis that low-grade inflammation might contribute to osteoporosis," said Mark Kotowicz, MD, associate professor of medicine at the University of Melbourne in Melbourne, Australia, and an investigator in the study. "Using high-sensitivity CRP [hsCRP] as a measure of inflammation to test that hypothesis, we found a positive association between hsCRP and subsequent risk of fracture, independent of bone density and independent of previous fracture," he says, noting that the data also suggest that hsCRP might offer a way to identify individuals with low bone density who might be at high risk for fracture.

These findings emerged from an analysis of 744 postmenopausal women enrolled in an osteoporosis study from 1994 to1997. Baseline hsCRP measurements were available for all of the women, and the median level for the study group was 2.5 mg/L.

During the follow-up through 2002, 126 fractures were recorded. Women with hsCRP levels in the highest quartile (>4.9 mg/L) had a relative fracture risk of 1.6 compared with women with lower hsCRP values. Women with high hsCRP values and low hip bone density had a relative fracture risk of 9. Increasing hsCRP values from quartiles 1-3 into the highest quartile was comparable to increasing the fracture risk normally associated with osteopenia to that of osteoporosis.

According to Dr. Kotowicz, hsCRP measurement might augment the predictive value of bone mineral density assessment to identify individuals with a high fracture risk.

Reference

1. Pasco JA, Kotowicz MA, Henry MJ, Spilsbury H, Nicholson GC, Box J, Schneider HG. Clinical and biomedical sciences: The association of high-sensitivity C-reactive protein levels with fracture risk in postmenopausal women: Geelong Osteoporosis Study. Presented at: 27^th Annual Meeting of the American Society for Bone and Mineral Research; September 23-25, 2005; Nashville, Tenn. Abstract F319.