Risk factors for fellow eye treatment in protocol T

Purpose: To identify risk factors for fellow eye treatment of diabetic retinopathy with Vascular Endothelial Growth Factor (VEGF) injections during the Diabetic Retinopathy Clinical Research Network (DRCR.Net) Protocol T trial METHODS: In this post-hoc analysis of randomized clinical trial data, Cox regression analysis was performed at 52 and 104 weeks to determine risk factors for treatment in 360 fellow eyes. Survival analysis was performed to determine mean time to treatment based upon medication used.

Results: Of 360 fellow eyes, 142 (39.4%) required treatment between weeks 4 and 104. Risk factors predicting a lower likelihood of year 1 treatment included older subject age (Hazard Ratio [HR]=0.98, 95% CI 0.96-0.99; p = 0.02) and higher baseline study eye ETDRS score (HR=0.98, 95% CI 0.97-0.99, p = 0.04). Center-involving DME at baseline in the fellow eye was predictive of a higher treatment need at both 52 (HR=1.89, 95% CI 1.42-2.51, p < 0.0001) and 104 weeks (HR=2.68, 95% CI 1.75-4.11, p < 0.0001). Subjects treated in the study eye with aflibercept (HR=0.574, 95% CI 0.371-0.887, p = 0.013) and ranibizumab (HR=0.58, 95%CI 0.36-0.94, p = 0.03) were less likely to require first year fellow eye injection than subjects treated with bevacizumab although this difference was no longer significant at week 104 (aflibercept HR=0.77, 95% CI 0.52-1.16, p = 0.21; ranibizumab HR=0.66, 95% CI 0.43-1.00, p = 0.05). Mean time to treatment was significantly shorter in the bevacizumab group (bevacizumab 25.83 weeks, aflibercept 38.75 weeks, ranibizumab 34.70 weeks (p=0.012)).

Conclusion: Bilateral treatment with intravitreal anti-VEGF injections was common during the DRCR.net Protocol T. Medication choice may impact the risk of fellow eye treatment.