Compliance with osteoporosis drug therapy and risk of fracture

Introduction Patient compliance with osteoporosis drug therapy is often poor in clinical practice and may be associated with higher risk of fracture. Methods A nested case-control study was undertaken using a US health insurance claims database. The source population included all women aged >= 45 years who began drug therapy for osteoporosis. Cases consisted of those who experienced an osteoporosis-related fracture; they were matched to controls without osteoporosis-related fracture. Compliance with osteoporosis drug treatment was assessed in terms of the number of therapy-days received and medication possession ratio (MPR). Conditional logistic regression was employed to examine the relationship between compliance and fracture risk. Results A total of 453 women with osteoporosis-related fracture were identified and matched to 2,160 controls. Fracture risk was significantly lower for patients with > 180 days of therapy [181-360 days: odds ratio (OR) = 0.70, 95% CI = 0.49-0.99; > 360 days: OR = 0.65, 95% CI = 0.43-0.99) versus those with <= 30 days. Risk was also lower for patients with MPR <= 90% (OR = 0.70, 95% CI = 0.52-0.93) versus those with MPR < 30%. Fracture risk decreased as compliance increased (p(trend) < 0.05). Conclusion Among women initiating drug therapy for osteoporosis, better compliance is associated with reduced risk of fracture.