Predicting Long-Term Effects of Ranibizumab Therapy on the Diabetic Retinopathy Severity Score (DRSS) based on the Short-Term DRSS Improvement in the Ranibizumab for Edema of the Macula in Diabetes – Protocol 3 with High Dose (READ-3) Study

Abstract

Purpose : To evaluate the role of degree of short-term improvement in diabetic retinopathy severity score (DRSS) after treatment with Ranibizumab in predicting long term effect on the DRSS in patients with diabetic macular edema (DME).

Methods : In the READ-3 study, patients with DME were stratified into two groups to receive either 0.5mg or 2.0mg monthly intravitreal ranibizumab until month 6, followed by pro-re-nata dosing until month 24. Seven field fundus photographs were evaluated utilizing a 9-step ETDRS DRSS, to assess DR severity at baseline, month 6, and month 24 by a centralized reading center. In the index study, patients from the study groups were combined and sub-divided based on their DRSS score into those with ≥2step (Group 1) improvement and <2 step improvement (Group 2) at month 24. Chi-square and t-test were used to assess the differences between age, gender, race, HbA1c, baseline DRSS, month 6 DRSS, and change in DRSS from baseline to month 6 (Delta M6) among the two groups. Logistic regression was utilized to assess the probability of ≥2step DRSS improvement at month 24 based on the baseline DRSS score and month 6 DRSS response.

Results : Out of 152 eyes (152 patients) randomized in the READ-3 study, 63 eyes (63 patients) fulfilled the inclusion criteria for the index study. Thirty-five eyes with the potential for improvement in the DR severity score were analyzed. Twenty-eight eyes had a prior history of PRP with baseline DR severity score 60. Amongst the 35 eyes, 11 eyes (31.4%) were from group 1 and 24 eyes (68.6%) were from group 2. There was no significant difference between age, gender, race, and HbA1c levels between the two study groups. There was a significant different between the study groups in terms of baseline DRSS, month 6 DRSS, and Delta M6 DRSS. Logistic regression analysis revealed baseline DRSS (p=0.028), month 6 DRSS (p<0.001), and Delta M6 (p<0.001), to be independent predictor of the month 24 DRSS outcomes (p<0.05).

Conclusions : Eyes demonstrating greater than 2-step improvement early in the management of diabetic retinopathy have a greater chance of demonstrating long term improvement in the DRSS score.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.