Effectiveness of denosumab for fracture prevention in real-world postmenopausal women with osteoporosis: a retrospective cohort study

Abstract

To determine denosumab's effectiveness for fracture prevention among postmenopausal women with osteoporosis in East Asia, the risk of fracture was compared between patients continuing denosumab therapy versus patients discontinuing denosumab after one dose. The real-world effectiveness was observed to be consistent with the efficacy demonstrated in the phase III trial.

Introduction: After therapeutic efficacy is demonstrated for subjects in global clinical trials, real-world evidence may provide complementary knowledge of therapeutic effectiveness in a heterogeneous mix of patients seen in clinical practice. This retrospective cohort study was conducted to compare the fracture risk in real-world clinical care received in Taiwan and Hong Kong between a treatment cohort (patients receiving denosumab 60 mg subcutaneously every 6 months) versus an off-treatment cohort (patients discontinuing after 1 dose of denosumab, which has no known clinical benefit) among real-world postmenopausal women.

Methods: This study included 38,906 and 2,835 postmenopausal women receiving denosumab in Taiwan and Hong Kong, respectively. The primary endpoint was hip fracture, and secondary endpoints were clinical vertebral and nonvertebral fractures. Propensity-score-matched analysis, adjusting for known covariates, was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). The robustness of findings was evaluated with a series of sensitivity and quantitative bias analyses.

Results: In this study, 554 hip fractures were included in the primary Taiwan population analysis. The crude incidence rate was 0.9 per 100 person-years in the treatment cohort (n = 25,059) and 1.7 per 100 person-years in the off-treatment cohort (n = 13,847). After adjusting for prognostic differences between cohorts, denosumab reduced the risk of hip fractures by 38% (HR = 0.62, CI:0.52-0.75). Risk reductions of similar magnitude were observed for the secondary endpoints and for the analysis of the smaller Hong Kong population.

Conclusion: The effectiveness of denosumab for fracture reduction among real-world postmenopausal women with osteoporosis was consistent with the efficacy demonstrated in a global clinical trial.

Registration: EnCePP registration number: EUPAS26372; registration date: 12/11/2018.

Keywords: Aging; Antiresorptives; Fracture prevention; Menopause; Osteoporosis.

Fig. 1

Study design schema

Fig. 2

Balance of covariates (N = 59) before and after propensity score matching—Taiwan. CCB = calcium channel blocker; ER = emergency room; SMD = standardized mean difference. SMD < 0.1 represents a difference between treatment and off-treatment cohorts that is not statistically significant. The covariates labeled in the figure are those with SMD > 0.1

Fig. 3

Kaplan–Meier plot of cumulative incidence of hip fracture in patients in the treatment and off-treatment cohorts—Taiwan population

Fig. 4

Results of subgroup analyses and sensitivity analysis for the primary endpoint of hip fracture—Taiwan population. BPs = bisphosphonates; HdPS = high-dimensional propensity score; HR = hazard ratio; IPTW = inverse probability of treatment weight