Elsevier

Mayo Clinic Proceedings

Volume 81, Issue 8, August 2006, Pages 1013-1022
Mayo Clinic Proceedings

ORIGINAL ARTICLE
Adherence to Bisphosphonate Therapy and Fracture Rates in Osteoporotic Women: Relationship to Vertebral and Nonvertebral Fractures From 2 US Claims Databases

https://doi.org/10.4065/81.8.1013Get rights and content

OBJECTIVE

To characterize the relationships between adherence (compliance and persistence) to bisphosphonate therapy and risk of specific fracture types in postmenopausal women.

PATIENTS AND METHODS

Data were collected from 45 employers and 100 health plans in the continental United States from 2 claims databases during a 5-year period (January 1, 1999, through December 31, 2003). Claims from patients receiving a bisphosphonate prescription (alendronate or risedronate) were evaluated for 6 months before the index prescription and during 24 months of follow-up to determine total, vertebral, and nonvertebral osteoporotic fractures, persistence (no gap in refills for >30 days during 24 months), and refill compliance (medication possession ratio ≥0.80).

RESULTS

The eligible cohort included 35,537 women (age, ≥45 years) who received a bisphosphonate prescription. A subgroup with a specified diagnosis of postmenopausal osteoporosis was also evaluated. Forty-three percent were refill compliant, and 20% persisted with bisphosphonate therapy during the 24-month study period. Total, vertebral, nonvertebral, and hip fractures were significantly lower in refill-compliant and persistent patients, with relative risk reductions of 20% to 45%. The relationship between adherence and fracture risk remained significant after adjustment for baseline age, concomitant medications, and fracture history. There was a progressive relationship between refill compliance and fracture risk reduction, commencing at refill compliance rates of approximately 50% and becoming more pronounced at compliance rates of 75% and higher.

CONCLUSIONS

Adherence to bisphosphonate therapy was associated with significantly fewer fractures at 24 months. Increasing refill compliance levels were associated with progressively lower fracture rates. These findings suggest that incremental changes in medication-taking habits could improve clinical outcomes of osteoporosis treatment.

Section snippets

Study Design

A retrospective cohort design was used to evaluate pharmacy and medical claims data. The study population was drawn from geographically diverse populations in the Medstat MarketScan Commercial Claims and Encounters and Medicare databases. Adjudicated claims from a 5-year period (January 1, 1999, through December 31, 2003), drawn from 45 employers and 100 health plans in the continental United States, were included in the analysis.

The Commercial Claims and Encounters database contains the health

Baseline Characteristics

The databases included 302,771 patients (Figure 1) who filled a bisphosphonate prescription between January 1, 1999, and December 31, 2003. Of these, 42,901 met theinclusion criteria, and 35,537 remained in the bisphosphonate cohort after exclusion criteria were applied. The mean patient age at the time the index prescription was filled was 65.3 years, and 59% of the women were between 55 and 74 years of age at index prescription (Table 1). Most women (85%; n=30,175) received an index

DISCUSSION

This retrospective analysis of a large population of bisphosphonate users followed up for 2 years demonstrated a significant association between adherence to bisphosphonate therapy and risk of osteoporotic fractures. Compared with patients who persisted with therapy, those with gaps in medication coverage had significantly more vertebral and nonvertebral fractures. Similar results were found when the records of those who were compliant and noncompliant were examined.

The current analyses were

CONCLUSIONS

The current study is among the largest observational studies to examine bisphosphonate therapy and fracture rates in osteoporotic women at least 45 years of age in the United States. This study also included 2 years of follow-up. Furthermore, the results contribute meaningful information by corroborating findings in earlier studies and extending them by examining site-specific fracture outcomes. Indeed, we observed a consistent and even greater reduction in fracture risk among compliant

Acknowledgments

We acknowledge Daniel R. Bretheim, MS, for his programming and database analysis; Gary Neidert, PhD, for his statistical contributions; and Ellen Lewis, PhD, and Stephanie Phillips, PhD, for their assistance with preparing the submitted manuscript.

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    This study was supported and funded by F. Hoffmann-La Roche, Ltd, and GlaxoSmithKline.

    Dr Siris has consulted for and received honoraria from Merck & Co, Inc, Eli Lilly, Novartis, Amgen Inc, Procter & Gamble, and sanofi-aventis, and she is on the speakers' bureau of Merck & Co, Inc, and Eli Lilly. Dr Harris has consulted for Amgen Inc, Eli Lilly, GlaxoSmithKline, Merck & Co, Inc, Novartis, Procter & Gamble, Roche Laboratories, Inc, sanofi-aventis, and Wyeth, and he is on the speakers' bureau of Eli Lilly, GlaxoSmithKline, Merck & Co, Inc, Procter & Gamble, Roche Laboratories, Inc, sanofi-aventis, and Wyeth. Dr Rosen has received research grants from sanofi-aventis, Eli Lilly, Merck, NPS Pharmaceuticals, and Wyeth. Dr Barr is an employee of Roche Laboratories, Inc. Dr Arvesen and his spouse have stocks in Merck & Co, Inc, and Procter & Gamble. Dr Abbott received financial support from Roche Laboratories, Inc, to conduct this study. Dr Silverman has received honoraria from the speakers' bureau and advisory board of Roche Laboratories, Inc.

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