Among 8,822 new female bisphosphonate users, non-compliant bisphosphonate use was associated with a 45% increased risk of osteoporotic fracture compared to compliant use (MPR ≥80%). Classifying compliance into five categories, fracture risk gradually increased with poorer compliance. These results emphasize the importance of treatment compliance in obtaining maximal treatment benefit. Introduction: Bisphosphonates are widely used to treat osteoporosis and reduce fracture risk. Low compliance is frequent and will limit treatment benefit. Methods: New female users of alendronate or risedronate between 1999-2004, aged ≥45 years were identified from PHARMO-RLS, including drug-dispensing and hospitalization data of ≥2 million residents of the Netherlands. Patients were followed until first hospitalisation for an osteoporotic fracture, death, or end of study period. Compliance with bisphosphonates during follow-up was measured over 90-day intervals using Medication Possession Ratio (MPR). The association between compliance and fracture risk was analyzed using time-dependent Cox-regression. Results: The study cohort included 8,822 new female bisphosphonate users, contributing in total 22,484 person-years of follow-up. During follow-up, 176 osteoporotic fractures occurred (excluding the first six months). Non-compliant bisphosphonate use was associated with a 45% increased fracture risk compared to compliant use (MPR ≥80%). Classifying compliance into five categories, fracture risk gradually increased with poorer compliance (p-value <0.05 for trend). A MPR <20% was associated with an 80% increased fracture risk compared to a MPR ≥90%. Conclusions: These results show a statistically significant association between level of compliance with bisphosphonates and level of fracture risk, emphasizing the importance of treatment compliance in obtaining maximal treatment benefit.

Benefit, Bisphosphonates, Fracture, Non-compliance, Osteoporosis
dx.doi.org/10.1007/s00198-007-0466-1, hdl.handle.net/1765/29894
Osteoporosis International: with other metabolic bone diseases
Erasmus MC: University Medical Center Rotterdam

Penning-Van Beest, F.J.A, Erkens, J.A, Olson, M, & Herings, R.M.C. (2008). Loss of treatment benefit due to low compliance with bisphosphonate therapy. Osteoporosis International: with other metabolic bone diseases, 19(4), 511–517. doi:10.1007/s00198-007-0466-1