Effectiveness of treatment initiation for secondary fracture prevention in the older population: Japanese Bone-fracture Osteoporosis in Late-stage population Database study (J-BOLD) – emulation of a randomized target trial

Initiating osteoporosis medication within 3 months after fracture reduces secondary fractures, particularly hip fractures, in individuals aged ≥ 75 years. This finding highlights the importance of early and sustained treatment in older populations. To evaluate the efficacy of initiating osteoporosis medication within 3 months after a fracture and continuing it for at least 6 months in preventing secondary fractures among individuals aged ≥ 75 years. This study used a targeted trial design, emulating a randomized controlled trial with Japanese administrative claims data from 2014–2022. Among 203,534 individuals with recent osteoporotic fractures, 40,063 initiated osteoporosis medication within 3 months (exposed), while 163,471 did not (controls). High-dimensional propensity score matching identified 53,436 individuals (26,718 exposed and 26,718 controls) for analysis. Cox regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for secondary fractures at any and specific sites. The study population had a mean age of 83.7 years and included 77.9% women. After ≥ 6 months of treatment, HRs for any fracture were 0.71 (95% CI: 0.60–0.86) in men and 0.78 (95% CI: 0.71–0.88) in women. For hip fractures, HRs were 0.56 (95% CI: 0.36–0.80) in men and 0.60 (95% CI 0.49–0.72) in women. After ≥ 12 months of treatment, HRs for any fracture were 0.65 (95% CI: 0.48–0.82) in men and 0.74 (95% CI: 0.68–0.85) in women. For hip fractures, HRs were 0.59 (95% CI: 0.19–0.84) in men and 0.55 (95% CI: 0.44–0.69) in women. Early initiation and sustained use of osteoporosis medication significantly reduced the risk of secondary fractures, particularly hip fractures, in men and women aged ≥ 75 years.