Background: A recent study found that high refill compliance (medication available ≥80% of the time) with a variety of prescribed osteoporosis therapies reduced fracture risk by 16% among women diagnosed with osteoporosis (Caro JJ. Osteoporos Int. 2004;15:1003.). The present study is the first to focus specifically on refill compliance as well as persistence (no gap in refills >30d) to bisphosphonate therapy and clinical outcomes (fracture risk) in a defined population of women with diagnosed postmenopausal osteoporosis (PMO).
Objective: To examine the relationship between adherence (refill compliance and persistence) and fracture risk over 24 months in women with PMO receiving newly prescribed bisphosphonate therapy.
Methods: A retrospective study of medical and pharmaceutical claims from the geographically diverse Medstat MarketScan® Research Databases (covering ≈6 million lives) analyzed outcomes in women diagnosed with PMO (ICD-9 code 733.01) who were ≥45 years of age and had received a first prescription for a bisphosphonate during a 30-month selection period (7/1/99 - 12/31/01). Exclusion criteria included Paget's disease of bone, prior bisphosphonates, prior cancer, or HIV. The occurrence of osteoporotic fractures was determined by a subset of ICD-9 codes.
Results: Of the 37,698 eligible women receiving a first bisphosphonate prescription, 6825 had a diagnosis of PMO. Over the 24-month study period, 48% of these were refill compliant and 21% were persistent. The relative risk of fracture was 26% lower among refill compliant women (9.4%) than in noncompliant (12.6%; P<.0001), and 21% lower in persistent women (9.1%) than in nonpersistent (11.6%; P=.0069).
Conclusions: Consistent with previous findings, this study found adherence rates with current bisphosphonate treatment to be suboptimal in women with PMO. However, women with good adherence were significantly less likely to experience fractures during 24 months of treatment. In order to gain a sense of the magnitude of the effect found in this study, if one extrapolated these results to the entire US population, with approximately 1.5 million osteoporotic fractures annually (NOF. 2004 http://www.nof.org/osteoporosis/diseasefacts.htm), proper treatment and adherence to bisphosphonate therapy could result in as many as 390,000 fewer fractures each year.
Disclosure Information:
Faculty Member's Name: Ethel S. Siris, MD
Grants/Research Support: Merck
Consultant: Lilly, Pfizer, Amgen, Novartis, Merck
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