Risk of severe gastrointestinal events in women treated with monthly ibandronate or weekly alendronate and risedronate

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.

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).

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.

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.

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.