Assessing adherence to teriparatide therapy, causes of nonadherence and effect of adherence on bone mineral density measurements in osteoporotic patients at high risk for fracture

OBJECTIVES: To determine (a) adherence rates at 6, 9 and 18 months amongst patients receiving teriparatide treatment for severe osteoporosis and (b) causes of therapy discontinuation and the effect of teriparatide on bone mineral density (BMD) in adherent and nonadherent patients at different time intervals. METHODS: A retrospective chart review of 111 patients receiving teriparatide from September 2004 to June 2007 was performed. Patients self-reports were used to record adherence and causes of nonadherence at 6, 9 and 18 months. BMDs for all patients were measured using the same DXA scanner at baseline and follow up. RESULTS: Of 111 participants, 17 were male (mean age 60 years) and 94 were female (mean age 69 years). Of these, 12 did not initiate therapy and 4 were lost to follow up. Reported adherence was 89.6% at 6 months, 87.6% at 9 months and 74.7% at 18 months. Causes of nonadherence included cost (n = 4), no benefit (n = 1) and adverse events (n = 8). Common adverse events were leg cramps (n = 9), headache (n = 5) and myalgia (n = 4). Mean spine and femur BMD changes were 3.30% and 0.67% at 4-9 months respectively, and 5.39% and 0.77% at 10-18 months respectively. CONCLUSION: Adherence to teriparatide was almost 90% at 9 months and decreased to 75% at 18 months. Adverse events led to nonadherence in 20% of patients. Those who were nonadherent had lower baseline BMD values than those who were adherent. Changes in BMD at the lumbar spine were greater than changes observed at the femoral neck.