The effect of a brief, unplanned treatment delay on neovascular age-related macular degeneration patients: a retrospective cohort study

Non-compliance to intravitreal anti-vascular endothelial growth factor (anti-VEGF) therapy can result in increased disease activity in neovascular age-related macular degeneration (nAMD). Our study aims to determine effects of unplanned delay in anti-VEGF injection treatment for nAMD. This retrospective observational study included patients with delays in receiving intravitreal injections for nAMD treatment from March to May 2020 by at least 21 days. Baseline demographic and clinical characteristics, visual acuity (VA), central macular thickness (CMT) measured on optical coherence tomography (OCT), and duration of delayed treatment were analyzed for 3 time points, the pre-delay visit (v1) and post-delay visits (v2 and v3). Data were compared to age-matched controls treated for nAMD in 2019 without delay. Demographic characteristics were compared using two-sample t-tests for continuous variables and Pearson’s chi-square tests for categorical variables. For the two primary outcomes of interest, VA and CMT, means and standard deviations were reported for each combination of group and time. Each outcome was modeled using a linear mixed model with the group, time and group-time interaction as fixed effects. A total of 69 patients (99 eyes) in the treatment delay group and 44 patients (69 eyes) in the control group were identified. Statistically significant differences between control and delayed groups were detected for VA (difference in mean logMAR = 0.16; 95% CI 0.06, 0.27; p = 0.002) and CMT (difference in mean CMT = 29; 95% CI 12, 47; p = 0.001) at v2. No differences were detected for v1 and v3 time points for both outcomes. An unplanned delay in intravitreal injection treatment for nAMD resulted in an increase in CMT and worsening of VA compared to controls observed at v2. At v3, CMT and VA recovered to near v1 levels. This study demonstrates that a one-time, brief interruption in treatment for nAMD results in reversible, temporary worsening.