Biochemical markers of bone metabolism and prediction of fracture in elderly women

We studied the ability of various markers of bone turnover to predict fracture in 1040 randomly recruited 75-year-old women. A total of 178 of the women sustained at least one fracture during follow-up (mean, 4.6 years). In elderly women, TRACP5b and urinary fragments of osteocalcin are promising new markers for prediction of fracture, in particular, vertebral fracture. Introduction: Biochemical markers reflecting bone turnover may improve the prediction of fractures. Materials and Methods: The ability of 10 markers of bone turnover to predict fracture in 1040 elderly women in the Malmo OPRA study was studied. Serum bone-specific alkaline phosphatase and four different forms of serum osteocalcin (S-OC) were analyzed as markers of bone formation and serum C-terminal cross-linking telopeptides of type I collagen (S-CTX), serum TRACP isoform 5b (S-TRACP5b) and urinary free deoxypyridinoline (U-DPD) as markers of bone resorption. Two novel assays for osteocalcin fragments in urine (U-OC) were analyzed. Areal BMD (aBMD) was measured by DXA in the femoral neck and lumbar spine. Results: In total, 231 fractures were sustained by 178 of the women during a 3- to 6.5-year (mean, 4.6 years) follow-up period. When women with prospective fractures were compared with women without fractures, S-TRACP5b, S-CTX, one S-OC, and one U-OC were higher in women with a fracture of any type (all p < 0.05), and all bone markers were higher in women with clinical vertebral fracture (all p < 0.05). Markers were not significantly elevated in women with hip fracture. When women within the highest quartile of a bone marker were compared with all others, S-TRACP5b and one U-OC predicted the occurrence of a fracture of any type (odds ratio [OR]), 1.55 and 1.53; p < 0.05). S-TRACP5b, the two U-OCs, and S-CTX predicted vertebral fracture (OR, 2.28, 2.75, 2.71, and 1.94, respectively; all p < 0.05), and the predictive value remained significant for S-TRACP5b and the two U-OCs after adjusting for aBMD (OR, 2.02-2.25; p < 0.05). Bone markers were not able to predict hip fracture. Conclusion: These results show that biochemical markers of bone turnover can predict fracture, and in particular, fractures that engage trabecular bone. S-TRACP5b and U-OC are promising new markers for prediction of fracture.