Adherence to bisphosphonate therapy and fracture rates in osteoporotic women: relationship to vertebral and nonvertebral fractures from 2 US claims databases.
OBJECTIVE
To characterize the relationships between adherence (complance and persistence) to bisphosphonate therapy and risk of specific fracture types in postmenopausal women.


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 > or = 0.80).


RESULTS
The eligible cohort included 35,537 women (age, > or = 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.
Siris
Ethel S
ES
Toni Stabile Osteoporosis Center, Department of Medicine, Columbia University Medical Center, Harkness Pavilion 9-964, 180 Fort Washington Ave, New York, NY 10032, USA. es27@columbia.edu
Harris
Steven T
ST
Rosen
Clifford J
CJ
Barr
Charles E
CE
Arvesen
James N
JN
Abbott
Thomas A
TA
Silverman
Stuart
S
D000368:Aged; D004164:Diphosphonates / Q000627:therapeutic use*; D011307:Drug Prescriptions; D005260:Female; D005500:Follow-Up Studies; D006620:Hip Fractures / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D015994:Incidence; D007345:Insurance Claim Review / Q000706:statistics & numerical data; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000150:complications / Q000188:drug therapy*; D010349:Patient Compliance; D012189:Retrospective Studies; D012307:Risk Factors; D016103:Spinal Fractures / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D014954:Wrist Injuries / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*
D004164:Diphosphonates