Comparison of Long-term Efficacy of Intravitreal Ranibizumab in Diabetic Retinopathy following Monthly vs Pro Re Nata vs Treat and Extend Protocol

Abstract

Introduction: Diabetic Retinopathy (DR) is a major complication of Diabetes Mellitus (DM), which remains a leading cause of visual loss in working age populations. The most common cause of vision loss in patients with DR is Diabetic Macular Oedema (DME). Intravitreal administration of anti-Vascular Endothelial Growth Factor (anti-VEGF) agents is currently the mainstay of therapy for both early and advanced stages of DR. Aim: To compare long-term change in Central Macular Thickness (CMT) and Best Corrected Visual Acuity (BCVA) in patients with Non Proliferative Diabetic Retinopathy (NPDR) with Clinically Significant Macular Oedema (CSME) after receiving Intravitreal Ranibizumab (IVR) following monthly, Pro Re Nata (PRN) protocol and Treat and Extend (T&E) protocol. Materials and Methods: This is a hospital based longitudinal prospective cohort study conducted on patients attending the Out Patient Department (OPD) of the Opthalmology Department at Midnapore Medical College and Hospital, West Bengal, India. from October 2018 to February 2021. Institutional Ethical clearance was obtained prior to the initiation of the study. Among 93 patients, 31 were chosen each for IVR PRN Monthly (Group A), (Group B) and T&E protocol (Group C) over a period of nine months. CMT and BCVA were measured at baseline and followed-up monthly for 12 months after last injection using Spectral Domain Optical Coherence Tomography (SD-OCT), while Glycated Haemoglobin (HbA1c) level was maintained below 7.4. Statistical analyses were performed using Statistical Package of Social Sciences (SPSS) statistics version 20 software. Chi-square test was used to find out the association between categorical variables. Pre and post comparisons were done using Wilcoxon sign rank test. A p-value less than 0.05 were considered as statistically significant. Results: There was significant decrease in CMT and betterment of BCVA in all groups at the end of treatment compared to baseline. At six months and one year of last injection there was no significant change in CMT in group A and C while group B at one year (p=0.0487) showed significant increase. There was no significant worsening of BCVA in group A and group C while group B (p=0.01) showed significant worsening at one year long-term follow-up. Conclusion: Thus, the present study concludes that, even though monthly protocol T&E protocol are equally good compared to PRN protocol on the basis of long-term beneficial effect, T&E protocol needed comparatively fewer doses of IVR compared to monthly protocol making it the choice of protocol for long-term control in NPDR with DME patients.

Keywords

• diabetic macular oedema
• glycosylated haemoglobin
• optical coherence tomography
• vascular endothelial growth factor