Association between bone turnover markers and the risk of imminent recurrent osteoporotic fracture

The association between bone turnover markers (BTMs) and the risk of imminent recurrent osteoporotic fracture (ROF) in the elderly remains unclear. The present study thus aimed to explore BTMs in relation to imminent ROF in the elderly with an index OF. For this purpose, data from a prospective cohort study were used for analysis. Elderly patients hospitalized due to an index OF were included and followed-up. The BTMs included bone resorption marker (C-terminal telopeptide of type I collagen) and the bone formation markers, procollagen type I N propeptide, osteocalcin (OC) and total alkaline phosphatase. The outcome was the time to the first ROF following their index fracture. Cox regression analysis was used to assess the association between BTMs and ROF. Model discrimination was calculated to explore whether the BTMs had potential to improve fracture risk prediction. There were 169 eligible patients included in the analysis (median age, 72 years; 87.6% females). During a median follow-up period of 10.5 months, there were seven ROFs (4.1%) observed. Serum OC levels were found to be significantly associated with the risk of ROF [hazard ratio, 0.13; 95% confidence interval (CI) 0.018-0.90; P=0.039] for per-SD increase in OC from multivariable analysis. After incorporating OC into the model, a C-index of 0.83 (95% CI, 0.70-0.96; P<0.001) was observed, which outperformed the model with bone mineral density alone (improvement for C-index, 0.29; 95% CI, 0.028-0.55). On the whole, the present study demonstrates a significant association between serum OC and the decreased risk of imminent ROF in the elderly with index fractures. However, further high-quality evidence is required to further clarify and validate the BTMs in relation to the imminent risk of ROFs among the elderly.