Differences in adherence to Osteoporosis Regimens: A 2-year analysis of a population treated under specific guidelines

Background: Patients' adherence to antiosteoporotic drug therapy is essential to prevent fracture and complications of osteoporosis over the long term. The guidance given in treating osteoporosis can potentially enhance adherence. Objective: This study was conducted to compare adherence to osteoporosis regimens by patients treated under specific guidelines in a medical center. Methods: This study used a database pertaining to the use of antiosteoporotic medication, including alendronate, raloxifene, and calcitonin, between 2001 and 2007. We selected patients who were being treated following the therapeutic recommendations of the National Osteoporosis Foundation or the guideline for glucocorticoid-induced osteoporosis recommended by the American College of Rheumatology. Adherence was determined by compliance and the persistence ratio (PR). Compliance was estimated by using the medication possession rate, and PR was determined by the percentage of patients with no medication refill gap for a period of ≥30 days. Results: A total of 2975 patients met the inclusion criteria. The patients were grouped according to treatment regimen: alendronate, n = 1745; raloxifene, n = 711; and calcitonin, n = 519. The good compliance rate (GCR; medication possession rate ≥80%) for alendronate, raloxifene, and calcitonin was 61.9%, 54.6%, and 36.4% at year 1 (P < 0.001), respectively. The GCR of alendronate was significantly higher than that for either raloxifene (P = 0.001) or calcitonin (P < 0.001). The GCR of the alendronate, raloxifene, and calcitonin groups at year 3 was 47.9%, 43.7%, and 36.4% of the included patients (P < 0.001). The PR of the alendronate, raloxifene, and calcitonin groups at year 1 was 57.1%, 50.2%, and 32.9% (P < 0.001) and 41.8%, 40.1%, and 23.5% (P < 0.001) at year 2. Conclusions: Alendronate had a better adherence profile than raloxifene and calcitonin at the end of year 1 and a better adherence profile than calcitonin at the end of year 2.