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Am J Med. 2007 Mar;120(3):251-6.

Gaps in treatment among users of osteoporosis medications: the dynamics of noncompliance.

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  • 1Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women's Hospital/Harvard Medical School, Boston, Mass 02120, USA.



Cyclical patterns of compliance have been observed with many health-related activities such as dieting and exercise. It is not known whether such patterns of compliance exist among users of chronic medications. We sought to estimate the percentage of patients who restart osteoporosis therapy after a prolonged lapse in medication use and to identify the factors associated with a return to compliance.


We studied 26,636 new users of an osteoporosis medication (alendronate, calcitonin, estrogen, raloxifene, or risedronate) who were age 65 or older and had an extended lapse in refill compliance, defined as a period of at least 60 days after the completion of one prescription in which no refill for any osteoporosis medication was obtained. Survival curves were used to estimate the length of time until therapy is resumed. We estimated the association between patient characteristics and the rate of resuming treatment using Cox proportional hazards analysis. We then conducted a case crossover analysis to examine whether certain events occurring during follow-up triggered a return to refill compliance.


Of patients who stopped therapy for at least 60 days, an estimated 30% restarted treatment within 6 months, and 50% restarted within 2 years. Among patients who had at least 6 months of continuous use before their interruption in treatment (n=5863), 42% restarted therapy within 6 months and 59% within 2 years. Younger patients, women, and those with a history of a fracture were more likely to return after a break in medication use. Recent hip fractures, discharges from nursing homes, and bone mineral density testing also predicted a return to treatment.


Extended gaps in treatment are common among users of osteoporosis medications. Because the effectiveness of these drugs used in an interrupted way is unknown, compliance interventions should emphasize the need for continuous medication use. Further research is needed to understand why patients often go for months without refilling prescriptions and also whether similar utilization patterns exist for other chronic medications.

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