Intravitreal Anti-VEGF Injection Transitions Across Bevacizumab, Biosimilar, and Branded Medications: The IRIS Registry Study

Purpose: To characterize antivascular endothelial growth factor medication transitions among patients with neovascular age-related macular degeneration (nAMD), including delays in care and economic impacts. Methods: A retrospective observational cohort study analyzed participants with nAMD in the IRIS (Intelligent Research in Sight) Registry who were treated with antivascular endothelial growth factor agents from 2015 to 2024. Four cohorts were analyzed: (1) bevacizumab only, (2) bevacizumab transitioned to a biosimilar, (3) bevacizumab transitioned to a branded agent, and (4) bevacizumab transitioned to a biosimilar and then to a branded agent. The main outcome measures were number of intravitreal injection events, transitions in medications, and injection intervals. Results: A total of 182 757 eyes with nAMD met inclusion criteria: 136 451 received bevacizumab only; 2184, bevacizumab followed by a biosimilar; 335, bevacizumab followed by a biosimilar, followed by branded medication; and 43 787, bevacizumab followed by a branded agent. Newer agents (faricimab and aflibercept 8 mg) experienced additional delays of 8.6 days compared with aflibercept 2 mg ( P < .001). Economic modeling based on IRIS transition rates and medication cost showed that bevacizumab transitioned to a biosimilar and then to a branded agent was 36.3% and 11.62% more costly than bevacizumab transitioned to a biosimilar ( P < .001) and bevacizumab transitioned to a branded agent ( P < .001), respectively, within 2 years. Similar cost differences persisted in 5- and 10-year projections. Bevacizumab transitioned to a biosimilar and then to a branded agent was the costliest pathway compared with transitions to biosimilars and branded agents, regardless of which branded agent was used. Conclusions: IRIS Registry cohort data suggest possible demographic differences in patients undergoing medication transitions, including biosimilar agents, as well as delays in care with medication transitions. Economic simulations suggest that multiple transitions may be more costly than direct transitions from bevacizumab to either biosimilar or branded agents.