The impact of acute fracture on interpretation of bone turnover marker measurements for patients starting anti-resorptive therapies.

Abstract

Bone turnover markers (BTM) are used in evaluating patients' response to anti-resorptive agents (ARA). Fracture and its healing process, however, can influence the measurements, which might make their interpretation difficult in patients with a recent fracture. We aimed to evaluate the effect of oral ARA on changes in BTM levels in patients with a recent distal radius fracture (DRF). In 143 women who had a new DRF and then received oral ARA including selective estrogen receptor modulator (SERM, n=101), and bisphosphonate (n=42), we measured serum cross-linked C-telopeptides of type I collagen (CTXI) and osteocalcin, at baseline and six months, as well as lumbar and total hip bone mineral density (BMD) at baseline and one year after fracture. We determined the predictive value of BTM at six months in determining one-year responses in BMD. Both BTM levels decreased significantly at six months, with the average decrease of 27±63% for CTX-I and 11%±37% for osteocalcin. The percent changes of BTM at six months were independent predictors of the BMD change. Cutoff points of 50.0% CTX-I decrease and 23.5% for osteocalcin decrease had the highest sensitivities and specificities for detecting BMD responders for bisphosphonate users, but cutoffs could not be found for SERM users. Although a fresh fracture can influence BTM, ARA therapy significantly reduced their levels and their percent change at six months could predict BMD improvement at one year. However, adjusted cutoff points can be necessary to increase sensitivity for detecting patients responsive to ARA treatment after a new DRF.