Adherence of bisphosphonate and decreased risk of clinical vertebral fracture in osteoporotic patients: A propensity score matching analysis

OBJECTIVES: Bisphosphonate is associated with a decreased risk of vertebral fractures due to osteoporosis. However, there are limited studies on how poor compliance with bisphosphonate affects the risk of vertebral fractures in a nationwide cohort. We aim to evaluate whether adherence to bisphosphonate affects the risk of fracture in osteoporosis patients. METHODS: We used the data of the Korean National Health Insurance Service Senior Cohort. A total of 33,315 (medication possession ratio [MPR]: 50) osteoporosis patients were matched using the propensity score matching method: those who received low-dose bisphosphonate and those who received high-dose bisphosphonate. Twenty-two confounding variables, including age, socioeconomic status, medications prescribed, and underlying diseases that may affect the risk of fracture were adjusted for propensity score matching. The risk of vertebral fracture was assessed by Cox proportional hazards regression. RESULTS: Patients with a higher MPR showed a decreased vertebral fracture risk than those with a lower MPR (MPR 50 = hazard ratio [HR] 0.909; 95% confidence interval [CI] 0.877–0.942 P < 0.001; MPR 70 = HR: 0.874, 95% CI: 0.838–0.913, P < 0.001; MPR 90 = HR: 0.822, 95% CI: 0.780–0.866, P < 0.001). MPR was associated with a decreased vertebral fracture risk in both groups with or without history of fracture. In the subgroup analysis, MPR was associated with a decreased vertebral fracture risk in women, in all ages, with or without T2DM, and with or without hypertension. CONCLUSIONS: Higher MPR is associated with a lower vertebral fracture risk.