Long-Term Oral Bisphosphonate Compliance Focusing on Switching of Prescription Pattern.

Background: Factors determining bisphosphonate compliance are not fully understood. We examined fluctuations in oral bisphosphonate dosing intervals to gauge therapeutic compliance in patients with osteoporosis. Materials and Methods: Hospital data accruing between 2010 and 2017 were accessed to retrospectively study patients >= 50 years old (N=1873), each prescribed bisphosphonate at initial diagnosis of osteoporosis. The medication possession ratio (MPR), calculated as total days supplied divided by length of follow-up, served to measure therapeutic compliance. We compared MPRs of various prescription patterns (daily, weekly, monthly, and switch [ie, >= 1 change in pattern] groups). We also analyzed the impact of age, sex, fracture history, surgical history, and comorbidities. Multiple regression analysis was ultimately performed, using MPR as a dependent variable. Results: In our cohort (mean follow-up=5.7 +/- 2.4 years), once weekly dosing was the most common prescription pattern (1223/1873, 65.3%), as opposed to monthly (366/1873, 19.5%) or daily (164/1873, 8.8%) dosing. A total of 120 patients (6.4%) comprising the switch group changed dosing patterns during the study period. MPR was significantly higher in the switch group (32.8 +/- 22.7) than in the other three groups (daily, 21.9 +/- 25.9; weekly, 22.7 +/- 27.3; monthly, 23.2 +/- 27.7). In multiple regression analysis, younger age (P<0.001), female sex (P=0.004), and switching of prescription pattern (decrease or increase frequency) were factors significantly associated with higher MPR, signaling better compliance. Conclusion: Better bisphosphonate compliance was associated with physician-modified dosing patterns. We therefore recommend adjustments of prescription intervals in poorly compliant patients requiring long-term treatment.