Effect Modification by Indication to the Risks of Major Thromboembolic Adverse Events in Patients Receiving Intravitreal Anti-Vascular Endothelial Growth Factor Treatment: A Population-Based Retrospective Cohort Study

Background: The association between intravitreal anti-vascular endothelial growth factor (anti-VEGF) treatment and the risk of major thromboembolic adverse events (TAEs) remains under debate. This study aimed to examine associated risks of TAEs in patients receiving intravitreal anti-VEGF treatment, and effect modification by different indications. Methods: This retrospective cohort study analyzed Taiwan’s National Health Insurance Database during 2011–2017 to identify neovascular age-related macular degeneration (nAMD) or diabetic macular edema (DME) patients newly receiving intravitreal aflibercept or ranibizumab. We followed up patients for 2 years, or until the occurrence of TAEs, including ischemic heart disease, ischemic stroke, transient ischemic attack, deep vein thrombosis, and pulmonary embolism, death, or the end of the study period (i.e., 31 December 2018). We compared the risk of TAEs between patients with aflibercept and ranibizumab using Cox-proportional hazard models. We examined statistical interactions between the anti-VEGF treatment (i.e., ranibizumab and aflibercept) and indications (i.e., nAMD and DME) with regard to the outcome of TAEs. Results: We included 12,215 nAMD and 7532 DME patients. Among nAMD patients, those receiving aflibercept had lower risk of TAEs (adjusted hazard ratio [HR] 0.85; 95% CI 0.77–0.94) compared with those receiving ranibizumab. However, among DME patients, those receiving aflibercept had no differences in the risk of TAEs (1.14; 0.97–1.35) compared with those receiving ranibizumab. Among patients treated with ranibizumab, the DME group had a higher risk of TAEs than the nAMD group (HR 1.15; 95% CI 1.03–1.28); similar results were observed in patients treated with aflibercept (HR 1.53; 95% CI 1.27–1.85). When DME patients were treated with aflibercept, the risk of TAEs was 31% higher than when nAMD patients were treated with ranibizumab (HR 1.31; 95% CI 1.09–1.56; p < 0.05). The p-value for statistical interaction between the anti-VEGF treatment and indications was 0.0033. Conclusions: Patients treated with aflibercept or ranibizumab for different indications may be associated with varying risk of TAEs. The findings provide evidence to support treatment selection, taking indications and TAE risk into consideration.