Osteoprotegerin and fractures in men and women with chronic kidney disease

Fractures are common in men and women with chronic kidney disease (CKD) but the best tool to identify those at high risk is unknown. Increased circulating osteoprotegerin (OPG) is associated with fractures in postmenopausal women. We determined if serum OPG was associated with prevalent fractures (self-reported low-trauma fractures since 40 years of age and/or prevalent vertebral fractures identified by radiographs) in men (n = 97) and women (n = 67) with stage 3–5 CKD. Analyses were performed unadjusted and adjusted for stage of CKD. Results are expressed as mean ± standard deviation (SD), and as odds ratio (OR) per SD increase in OPG with 95 % confidence intervals (CI). The mean age was 62.7 ± 16.3 years, and mean weight was 78.9 ± 18.7 kg. Compared to those without fractures, those with fractures (n = 55) were older (p < 0.01). Serum OPG increased as kidney function decreased, and OPG was higher in those with fractures compared to those without (9.42 ± 4.08 vs 8.06 ± 3.11 pmol/L, p = 0.02). After adjusting for stage of CKD, increased OPG was associated with an increased fracture risk (OR 1.13, 95 % CI 1.02–1.25); however, OPG did not discriminate fracture status well (area under the receiver operating characteristic curve 0.61, 95 % CI 0.52–0.70). OPG is associated with fractures in men and women with stage 3–5 CKD; however, the ability of OPG to discriminate fracture status is poor and cannot be used in isolation to assess fracture risk. Further studies should examine the ability of OPG in combination with other risk factors to better discriminate fracture status in men and women with CKD.