Patient preference and adherence: comparative US studies between two bisphosphonates, weekly risedronate and monthly ibandronate

Objectives: : To determine how patients' preferences for weekly versus monthly bisphosphonate therapy is influenced by their knowledge of the medication's proven fracture efficacy. An additional objective is to determine whether patient adherence to therapy with weekly risedronate versus monthly ibandronate is related to patient preferences preferences. Methods: Preference data were collected for weekly versus monthly bisphosphonate therapy among women currently using bisphosphonates. In addition, the IMS longitudinal prescription database was used to evaluate adherence among patients currently taking weekly risedronate or monthly ibandronate, using three cohorts: overall sample; new to osteoporosis therapy; and 6 months after initial market availability. Results: More patients preferred weekly over monthly therapy ( 82% vs. 18% respectively, p < 0.0001) after receiving information about fracture efficacy differences. Mean compliance was significantly higher for the overall sample and the post-market group. Mean persistence for risedronate versus ibandronate patients was significantly different ( p < 0.0001) for the overall sample ( 144.3 +/- 55.5 days vs. 100.1 +/- 67.4 days), new to therapy ( 103.5 +/- 66.4 days vs. 92.1 +/- 65.9 days), and post-market ( 104.8 +/- 67.3 days vs. 92.1 +/- 65.9 days). Adherence was significantly higher ( p < 0.0001) in patients taking risedronate versus ibandronate in all groups ( 72.7 +/- 26.4% vs. 52.8 +/- 31.5%, overall sample; 51.7 +/- 31.3% vs. 46.6 +/- 30.7%, new to therapy; 53.0 +/- 32.2% vs. 46.6 +/- 30.7%, post-market). In the persistence analyses, biases might have occurred due to the methodology of breaking down the dose of the bisphosphonate the patient received during the index month, as well as due to the selected refill gap length. Conclusions: Patients preferred a weekly dosing regimen with proven vertebral and non-vertebral fracture efficacy. A monthly dosing regimen did not increase patient compliance and persistence with bisphosphonate therapy in this study. However, patient compliance, persistence and adherence are complex, and methods to increase adherence beyond dosing schedules should be further investigated.