Intravitreal Anti-Vascular Endothelial Growth Factor Therapy for Diabetic Macular Edema in Türkiye: 48-Month Data, BOSPHORUS-DME Study Group Report No. 1.

Objectives: This study aimed to evaluate the 48-month visual and anatomical outcomes, as well as the number of clinic visits and intravitreal injections, in patients treated with three consecutive loading doses of intravitreal anti-vascular endothelial growth factor (anti-VEGF) therapy for diabetic macular edema (DME) under real-world conditions in Türkiye. Materials and Methods: In this retrospective, multicenter study conducted by the BOSPHORUS-DME Study Group, the medical records of 2,424 eyes of 1,696 patients who experienced vision loss due to DME and were treated with intravitreal anti-VEGF injections between January 2019 and January 2023 were reviewed. The study was carried out across eight tertiary referral hospitals located on the European side of İstanbul and in the province of Kocaeli. Seven cohort groups were created based on follow-up at baseline and months 3, 6, 12, 18, 24, 36, and 48. Best-corrected visual acuity (BCVA), central macular thickness (CMT), the number of clinic visits and injections, and the rates of anti-VEGF or dexamethasone switching were analyzed. Results: The study included a total of 2,424 eyes of 1,696 patients (mean age: 60.6±10.0 years; 46.4% female). The mean baseline BCVA and CMT were 0.34±0.24 (decimal) and 400±134 μm, respectively. At month 48, these values improved to 0.49±0.29 (p<0.0001) and 324±115 μm (p<0.0001). The mean cumulative number of injections at years 1, 2, 3, and 4 were 6.5, 9.6, 12.2, and 15.7, respectively. A switch in anti-VEGF therapy occurred between month 3 and 6 in 43.5% of eyes, mostly due to mandatory transition to on-label agents. Conclusion: This is the largest and longest real-world study on DME treatment conducted in Türkiye. It demonstrates that visual and anatomical gains can be sustained over a 48-month period. While the overall trend aligns with previous real-world studies, the higher injection frequency in our cohort appears to have contributed to more favorable outcomes. These findings underscore the importance of early intensive therapy and sustained treatment adherence in the real-world management of DME.