Diabetic Retinopathy May Require Greater Interval Between Anti-VEGF Treatments

David G. Miller, MD

New findings suggest that patients diagnosed with retinal vein occlusion (RVO) or wet age-related macular degeneration (wetAMD) have a shorter interval of time between anti-VEGF injections compared to patients diagnosed with diabetic retinopathy (DR).

Data show the interval between anti-VEGF injections in patients with RVO compared to DR was 15.72 days, while patients with wetAMD exhibited a statistically significant difference in interval compared to DR at 15.01 days.

“There does not appear to be a significant difference in average injection interval between patients diagnosed with RVO and wAMD,” wrote study author David G. Miller, MD, Retina Associates of Cleveland Inc.

These findings were presented at the Association of Research in Vision and Ophthalmology (ARVO) 2022 Meeting in Denver, Colorado.

The average interval between anti-VEGF injections is defined as the number of days before a patient requires a consecutive injection for disease treatment. The current retrospective study calculated and compared the average interval between anti-VEGF injections for patients with DR, RVO, and wetAMD.

Investigators collected data from patients who received anti-VEGF injections of aflibercept, bevacizumab, brolucizumab, and ranibizumab from July 2020 - July 2021. It included patient number, injection service dates, injection service ID’s, procedure codes, and primary diagnoses.

The study data set was organized by primary diagnosis and average number of days between anti-VEGF injections. Then, statistical analysis was conducted using average injection interval and two-tailed t tests.

During the study period, a total of 14,911 patients were injected unilaterally. Investigators studied 1,313 DR patients with an average injection interval of 70.02 days. Additionally, there were 2,809 RVO patients with an average injection interval of 54.30 days and 10,789 wetAMD patients with an average injection interval of 55.01 days.

By comparing the average interval between anti-VEGF injections for DR versus RVO, a two-tailed t-test calculated a P-value of P <.01. Further, when comparing average interval between anti-VEGF injections for DR versus wetAMD, a two-tailed t-test calculated a P-value of P <.01.

Moreover, when comparing average interval between anti-VEGF injections for RVO versus wetAMD, a two-tailed t-tests calculated a P-value of P =.25.

Investigators noted limitations of the study included the single practice location, different types of anti-VEGF medications yield varied results, and patients may develop macular edema at different rates.

They additionally noted that the average interval of treatment between intravitreal anti-VEGF treatment across multiple practices distinguished by type of pathology may be necessary to investigate further.

“Further studies may be needed to explore injection data and study results categorized by severity of patient disease (mild, moderate, severe) in order to account for confounding disease progression,” Miller concluded.

The study, “Comparison of Average Interval between Anti-Vascular Endothelial Growth Factor (Anti-VEGF) Injections in Diabetic Retinopathy, Retinal Vein Occlusions, and Wet Age-Related Macular Degeneration,” was presented at ARVO 2022.