Differences in the characteristics of subjects achieving complete, partial, or no resolution of macular edema in the READ-3 study

Abstract

Purpose : To identify baseline characteristics of subjects enrolled in the READ-3 study that would predict the response of macular edema to ranibizumab (RBZ) therapy at year 1. Methods : In this post hoc analysis of the READ-3 randomized, multicenter phase 2 clinical trial, subjects with diabetic macular edema (DME) were randomized to receive monthly intravitreal injections of RBZ (0.5 or 2.0 mg) for 6 consecutive injections followed by as-needed treatments based on pre-defined retreatment criteria. In this sub-study, subjects were divided into three groups (persistent, rebound, and resolved) based on edema status at month 12 (M12). Multi-logistic regression was utilized to assess the probability of edema outcomes M12, based on the baseline characteristics. Results : One hundred twenty-three out of 152 subjects were analyzed for this sub-study. A significant difference was observed in the baseline (BL) central subfield thickness (CST) among the study groups (p < 0.05). BL CST was a significant predictor for edema outcome at M12 with > 80% probability of the subject having persistent edema if BL CST was > 570 mu m (p < 0.05). This association persisted when controlled for the dose of RBZ (relative risk (RR), 1.007; p < 0.05). BL CST was also a significant predictor for having persistent edema at M12 in subjects without vitreomacular adhesion (VMA) (> 80% probability of edema persistence at CST > 570 mu m [RR, 1.006; p < 0.05]). However, in the presence of VMA, BL CST was no longer a significant predictor of having persistent edema at month 12 (RR, 1.005; p > 0.05). Conclusions : Subjects with high CST (> 570 mu m) at baseline may not benefit from repeated intravitreal injections of anti-VEGF for resolution of edema.