Weekly versus monthly drug regimens: 1-year compliance and persistence with bisphosphonate therapy

ABSTRACT

Objective: To determine compliance and persistence with weekly risedronate and monthly ibandronate therapy.

Research design and methods: The IMS longitudinal prescription database was used to evaluate compliance (mean medication possession ratio), persistence (days until a gap >90 days between prescriptions occurred) and cumulative drug availability (ratio of drug supply and days between first fill date and the end of the study) among patients taking weekly risedronate or monthly ibandronate over a 12-month period using three retrospective cohorts: overall sample, new to osteoporosis therapy, and new to osteoporosis therapy after initial market availability. Comparisons were made between drug groups for each measure.

Results: Compliance was significantly different for the overall sample (80.15 ± 18.90% for risedronate vs. 74.68 ± 22.56% for ibandronate; p < 0.0001), and marginally different during the initial post-marketing year (p = 0.091), but not for patients new to therapy (p = 0.693). Persistence was significantly different for the overall sample (250.04 ± 132.34 days for risedronate vs. 151.54 ± 137.24 days for ibandronate; p < 0.0001), for patients new to therapy (154.38 ± 135.29 days for risedronate vs. 133.33 ± 130.36 days for ibandronate; p < 0.0001), and after initial market availability (165.00 ± 141.58 days for risedronate vs. 133.33 ± 130.36 days for ibandronate; p < 0.0001). Mean cumulative drug availability was significantly different for the overall sample (64.54 ± 29.86% for risedronate vs. 43.38 ± 32.96% for ibandronate; p < 0.0001), for patients new to therapy (40.34 ± 31.84% for risedronate vs. 36.05 ± 31.09% for ibandronate; p < 0.0001), and after initial market availability (43.17 ± 33.34% for risedronate vs. 36.05 ± 31.09% for ibandronate; p < 0.0001).

Conclusions: Patient compliance, persistence and cumulative drug availability were similar for monthly ibandronate and weekly risedronate dosing. Interpretations from this study are limited by assumptions of persistence based on initial drug dosing and selected refill gap length measured. Furthermore, comparisons with earlier studies are difficult, due to differences in definitions of compliance and persistence. Further studies are needed to explore factors affecting patterns of medication use, particularly the effects of patient preference, acceptance, and patient education on compliance and persistence.

Key words: :

• Adherence
• Bisphosphonates
• Compliance
• Ibandronate
• Osteoporosis
• Persistence
• Risedronate

Transparency

Declaration of funding

This study was funded by The Alliance for Better Bone Health (Procter & Gamble Pharmaceuticals and Sanofi-Aventis).

Declaration of financial/other relationships

D.T.G. has disclosed that she is a consultant and speaker for Amgen, Eli Lilly, GlaxoSmithKline, Merck, Procter & Gamble, Roche Pharmaceuticals, and Sanofi-Aventis. H.T. and W.S. have disclosed that they are employees of P&G Pharmaceuticals. The authors have disclosed that they received editorial/writing support in the preparation of this manuscript, funded by the Alliance for Better Bone Health.

All peer reviewers receive honoraria from CMRO for their review work. Review 1 has disclosed that he has received research grants from Eli Lilly, Forest Laboratories and Lundbeck A/S, and that he is on the speakers’ bureau of Sanofi-Aventis. The other reviewer has disclosed that he/she has no relevant financial relationships.

Acknowledgment

The authors thank Andrea Klemes, DO of Procter & Gamble for her valuable input in the development of this manuscript. All authors were involved in the design of the study, the statistical analysis of the data and the preparation of the manuscript. The authors are fully responsible for the contents of and editorial decisions in this manuscript.