Baseline serum PINP level is associated with the increase in hip bone mineral density seen with Romosozumab treatment in previously untreated women with osteoporosis

Summary Baseline serum PINP value was significantly and independently associated with the increased bone mineral density (≥ 3%) in both total hip and femoral necks by 12 months of romosozumab treatment in patients with treatment-naive postmenopausal osteoporosis. Purpose Some patients fail to obtain a sufficiently increased hip bone mineral density (BMD) by romosozumab (ROMO) treatment. This study aimed to investigate the prognostic factor for increased hip BMD with ROMO in patients with treatment-naive postmenopausal osteoporosis. Methods This prospective, observational, and multicenter study included patients ( n = 63: mean age, 72.6 years; T-scores of the lumbar spine [LS], − 3.3; total hip [TH], − 2.6; femoral neck [FN], − 3.3; serum type I procollagen N-terminal propeptide [PINP], 68.5 µg/L) treated by ROMO for 12 months. BMD and serum bone turnover markers were evaluated at each time point. A responder analysis was performed to assess the patient percentage, and both univariate and multivariate analyses were performed to investigate the factors associated with clinically significant increased BMD (≥ 3%) in both TH and FN. Results Percentage changes of BMD from baseline in the LS, TH, and FN areas were 17.5%, 4.9%, and 4.3%, respectively. In LS, 96.8% of patients achieved ≥ 6% increased LS-BMD, although 57.1% could not achieve ≥ 3% increased BMD in either TH or FN. Multiple regression analysis revealed that only the baseline PINP value was significantly and independently associated with ≥ 3% increased BMD in both TH and FN ( p = 0.019, 95% confidence interval = 1.006–1.054). The optimal cut-off PINP value was 53.7 µg/L with 54.3% sensitivity and 92.3% specificity (area under the curve = 0.752). Conclusions In a real-world setting, baseline PINP value was associated with the increased BMD of TH and FN by ROMO treatment in treatment-naive patients.