Author’s Name(s): Marko Popovic, Ryan Huang, Sumana Naidu, Andrew Mihalache, Peter Kertes, David Sarraf, SriniVas Sadda, Rajeev Muni, Radha Kohly

Author’s Disclosure Block: Marko Popovic, none; Ryan Huang, none; Sumana Naidu, none; Andrew Mihalache, none; Peter Kertes, none; David Sarraf, none; SriniVas Sadda, none; Rajeev Muni, none; Radha Kohly, none

Abstract Body
Purpose: To investigate the sociodemographic and clinical factors associated with being lost to follow-up (LTFU) among patients with proliferative diabetic retinopathy (PDR) and diabetic macular edema (DME) requiring treatment. Study Design: Multi-center, retrospective review of medical records from patients with PDR and DME treated by two retina specialists in Toronto, Canada from 2012-2021. Methods: All patients received at least one anti-vascular endothelial growth factor (anti-VEGF) intravitreal injection (IVI) or panretinal photocoagulation (PRP) session for PDR or DME over the duration of follow-up. The primary outcome was the proportion of patients LTFU, defined as the absence of an ophthalmic visit or intervention in the one-year period following a patient’s last visit with their treating retinal specialist. We evaluated the relationship between sociodemographic and clinical patient characteristics with the incidence of being LTFU. Univariable and multivariable logistic regression models, adjusted for age, sex, and lens status, were conducted on Stata v17.0. Results: Overall, 2,961 patients with PDR and DME (mean age: 71 ± 13 years old) were included, of whom 507 (17%) were LTFU over a mean follow-up period of 61 ± 22 months. Older patients (≥85 years, OR=0.59, 95%CI=0.54-0.90, p<0.01, compared to <65 years) and those with worse baseline visual acuity (>20/200 Snellen, OR=0.71, 95%CI=0.50-0.96, p=0.04, compared to ≤20/40 Snellen) were less likely to be LTFU. In contrast, male patients (OR=1.25, 95%CI=1.03-1.51, p=0.04, compared to female) and those living farther from the point of care (>200 km, OR=2.74, 95%CI=1.99-3.77, p<0.01, compared to <20km) had a higher odds of being LTFU. Patients with DME (OR=0.65, 95%CI=0.48-0.90, p<0.01) had a lower odds of being LTFU compared to those without DME, although no significant difference in risk was observed in patients with PDR compared to those without PDR at the initial visit. Additionally, frequent clinic visits (≥6 visits, OR=0.78, 95%CI=0.62-0.98, p=0.03) and high anti-VEGF IVI burden (OR=0.39, 95%CI=0.19-0.77, p<0.01) in the first year were associated with a lower LTFU rate. Patients treated for PDR with PRP at their initial visit were more likely to be LTFU compared to those treated with anti-VEGF IVIs (OR=2.18, 95%CI=1.22-3.51, p<0.01). Conclusion: The odds of patients with PDR and DME being LTFU were significantly higher among males, those living farther from the point of care, and patients with fewer follow-up appointments or a lower IVI burden. A higher LTFU rate was observed in patients receiving PRP compared to IVI. It is imperative for clinicians to appreciate the complex interplay of factors associated with patients being LTFU, which will help inform targeted strategies for reducing LTFU rates in this setting.