Serum type I collagen breakdown product (serum CTX) predicts hip fracture risk in elderly women: The EPIDOS study

We report the predictive value for hip fracture of a new marker of hone res orption, serum C-telopeptide of type I collagen (CTX), measured on a new au tomated analyzer, Elecsys, Baseline urinary and serum samples From 212 pati ents who subsequently had a hip fracture and from 642 controls were analyze d in a nested case control study within the EPIDOS prospective cohort. Each fracture patient was matched with three control patients of the same age w ho did not fracture, Mean follow-up was 3.3 years (maximum 4.9 Scars). We m easured urinary CTX, urinary free deoxypyridinoline, and serum CTX. Urinary markers were assessed to know whether the magnitude of prediction of hip f racture by this serum marker was similar compared with that given by urinar y markers, In the whole group, serum CTX was not predictive of hip fracture risk, When the analysis was restricted to samples taken in the early after noon (between 1 and 2 P.M.), representing 115 fracture cases and 293 contro ls, serum CTX was significantly predictive with a relative hazard of 1,86 ( 95% confidence interval 1.01-3.76) for values above the premenopausal range (mean + 2 SD). For comparison, in the whole group, the relative hazard for fracture of women having a T-score greater than or equal to 2 for urinary CTX and free deoxypyridinoline was 1.67 (1.19-2.32), and 2.07 (1.49-2.9), r espectively. Serum CTX front morning samples did not predict hip fractures probably because it was not controlled for time and fasting/nonfasting stat e. We conclude that serum CTS sampled under controlled conditions significa ntly predicts the subsequent risk of hip fracture in ambulatory elderly wom en, with the same magnitude as urinary markers of resorption. (C) 2000 by E lsevier Science Inc. All rights reserved.