Risk of Severe Gastrointestinal Events in Women Treated with Monthly Ibandronate or Weekly Alendronate and Risedronate

BACKGROUND: Bisphosphonate (BP)-related gastrointestinal (GI) adverse events can lead to discontinuation of osteoporosis treatment. Irritation of the GI tract related to BPs may be worsened by more frequent administration. OBJECTIVE: To compare the number of women who experienced severe GI events within 3 months of starting once-monthly oral ibandronate with those starting once-weekly oral BP (alendronate or risedronate). METHODS: In a retrospective database study design, eligible women with a new prescription for monthly ibandronate were propensity-matched to women with a new weekly BP prescription. Patients had continuous health plan enrollment for 6 months prior to the index date and for 3 months after the index date. Women with previous intravenous BP treatment, Paget's disease, or oral BP treatment within the 6-month preindex period were excluded. Severe GI events (including acute events involving perforation or bleeding/perforation) within 3 months of treatment initiation were identified by ICD-9 and Current Procedural Terminology codes. A post hoc analysis assessed treatment discontinuation after severe GI events. GI-related healthcare utilization rates and costs were also compared. RESULTS: Of the 8608 patients per group, 45 (0.52%) who were receiving monthly ibandronate and 70 (0.81%) of those receiving weekly BP treatment experienced a severe GI event. Ibandronate patients had a 36% reduction in the risk of severe GI events compared with weekly BP users (OR 0.64, 95% CI 0.44 to 0.93). Significantly more women receiving a weekly BP discontinued treatment after a severe GI event compared with those receiving ibandronate (100% vs 55.6%; p < 0.001). Most healthcare utilization outcomes were not significantly different between the 2 groups; outpatient visits were significantly higher for ibandronate (p = 0.02). Costs were not significantly different between the 2 groups. CONCLUSIONS: Patients receiving monthly ibandronate therapy had a significantly reduced risk of severe GI events compared with those receiving weekly BP treatment. In addition, patients receiving a weekly BP were more likely to discontinue treatment after a severe GI event.