Loss to Follow-Up and Subway Proximity in Proliferative Diabetic Retinopathy and Diabetic Macular Edema: CLEAR Study Report 2

PURPOSE: To investigate the association between home subway proximity and being lost to follow-up (LTFU) in patients with proliferative diabetic retinopathy (PDR) or diabetic macular edema (DME). METHODS: This multi-center, retrospective cohort study included patients from the Greater Toronto Area with available residential address data who were treated with either intravitreal anti-vascular endothelial growth factor therapy or panretinal photocoagulation for PDR or DME between January 1st, 2012, and December 31st, 2021. LTFU was defined as the absence of an ophthalmic visit within one year of their most recent visit. Univariable and multivariable logistic regression models assessed associations between these transportation variables and LTFU status. RESULTS: Among 2,755 patients with PDR or DME (mean age: 71 ± 13 years) who had available residential address data, 477 (17%) were LTFU over a mean follow-up period of 59 ± 19 months. In the multivariable analysis adjusting for total distance to the point of care and relevant confounding variables, patients residing farther from a subway station were more likely to be LTFU (>10 km: OR=2.04, 95%CI=[1.44-2.91], p<0.001). Patients requiring more subway stops (>10 stops: OR=1.51, 95%CI=[1.10-2.39], p=0.015) and line transfers (1 transfer: OR=1.63, 95%CI=[1.29-2.05], p<0.001) were more likely to be LTFU. Longer estimated travel times were also significantly associated with LTFU (>60 minutes: OR=2.07, 95%CI=[1.86-2.95], p<0.001). CONCLUSION: Limited subway proximity was associated with an increased odds of being LTFU, highlighting the importance of addressing transportation barriers and improving the accessibility of ophthalmic care in areas with limited public transit infrastructure to improve follow-up adherence.