Early and Long-Term Responses to Anti-Vascular Endothelial Growth Factor Therapy in Diabetic Macular Edema: Analysis of Protocol I Data

Abstract

Purpose: To determine whether early visual acuity response to ranibizumab in diabetic macular edema is associated with long-term outcome.

Design: Post hoc analysis of randomized controlled trial data.

Methods: Pooled data from the ranibizumab plus prompt and deferred laser treatment arms of the Diabetic Retinopathy Clinical Research Network's Protocol I study were used to explore the relationship between early (week 12) and late (weeks 52-156) visual acuity response (mean change from baseline in best-corrected visual acuity [CFB BCVA]; categorized improvement [<5, 5-9, or ≥10 Early Treatment Diabetic Retinopathy Study (ETDRS) letters] in BCVA).

Results: In the analysis population (340 eyes), <5-, 5- to 9-, and ≥10-letter BCVA improvements occurred in 39.7%, 23.2%, and 37.1% of eyes, respectively, at 12 weeks, and 34.2%, 16.5%, and 49.3% of eyes at 156 weeks. Within each early BCVA response category (<5, 5-9, and ≥10 letters of improvement at 12 weeks), mean CFB BCVA at 52-156 weeks varied by <5 letters from that at 12 weeks. CFB BCVA and <5-letter improvement at 12 weeks showed significant positive and negative association, respectively, with CFB BCVA and ≥10-letter improvement at 52 and 156 weeks. Similar relationships were demonstrated in eyes with baseline BCVA <69 letters, and associations remained significant after multivariate adjustment for potential confounders.

Conclusions: Ranibizumab ± laser therapy resulted in similar rates (∼40%) of suboptimal (<5-letter) and pronounced (≥10-letter) BCVA improvement at 12 weeks. Eyes with suboptimal early BCVA response showed poorer long-term visual outcomes than eyes with pronounced early response (mean improvement 3.0 vs 13.8 letters at 156 weeks).