The effect of sample medication use on subsequent anti-VEGF agent selection for neovascular age-related macular degeneration

Purpose: To examine the effect of medication sample use (ranibizumab or aflibercept) on future anti-vascular endothelial growth factor (VEGF) agent selection in neovascular age-related macular degeneration (nvAMD). Design: Retrospective cohort study. Methods: nvAMD patients who underwent an initial anti-VEGF injection with a sample medication were compared to nvAMD control patients who never received a medication sample. Charts from 2017 through 2020 were reviewed for data regarding demographics, anti-VEGF agent selection, and visual acuity outcomes for both groups. Anti-VEGF agent selection for the first four injections and at one year were examined in both the sample and control groups. Results: Adherence to the initial agent was high between first and subsequent injections (2nd, 3rd, 4th injection, and 1 year) in both sample (96.2%, 95.9%, 91.9%, 93.4%, respectively) and control groups (98.1%, 94.2%, 94.9%, 87.8%, respectively). Bevacizumab usage was significantly lower among eyes receiving samples relative to controls at the second (1.9% vs. 38.7%, p<0.001), third (3.1% vs. 41.3%, p<0.001), fourth injections (4.7% vs. 40.4%, p<0.001), and at 1 year (0% vs. 33.8%, p<0.001). Aflibercept usage was significantly higher in sample eyes relative to controls at the second (78.3% vs. 43.4%, p<0.001), third (76.3% vs. 41.5%, p<0.001), and fourth injections (76.7% vs. 43.4%, p<0.001), and at 1 year (77.0% vs. 52.7%, p<0.001). Conclusions: Eyes receiving a sample anti-VEGF agent (ranibizumab or aflibercept) for their initial injection were less likely to receive bevacizumab at future visits relative to eyes that did not receive an anti-VEGF sample, even after one year of treatment.