The Association of Vertically Integrated Delivery Networks on Lapses in Diabetic Retinopathy Care and Presenting Diabetic Retinopathy Severity

Purpose: Vertical integration of ophthalmologists with primary care providers (PCP) may improve diabetic retinopathy (DR) by reducing lapses in care and promoting early detection. We examine how PCP integration impacts DR outcomes, and whether that relationship is affected by the distance patients live from the health system. Methods: This retrospective cohort study included adults (≥18 years) with diabetes mellitus seen at the Wilmer Eye Institute from April 2013 to September 2023. The primary exposure was PCP type, classified as internal (within the Johns Hopkins Health System Corporation) or external. To assess whether PCP integration effects varied by distance, an interaction term with distance to clinic (≤7.6 vs. >7.6 miles) was included. The primary outcome was lapse in care, or not returning as recommended. Secondary outcomes, defined at the initial DR screening visit, were vision impairment, blindness, visual acuity (in logMAR), and DR severity. Multivariable regression models adjusted for age, race, insurance, comorbidities, and ocular disease. Results: A total of 41,581 patients were included, and 81% had at least one lapse in care in two years. For lapses in care, having an external PCP, compared to internal, was associated with a 19% higher odds of a lapse but only for patients who lived >7.6 miles away. Having an external PCP was also associated with more severe disease at presentation regardless of the distance patients lived from the clinic, including: higher odds of vision impairment, blindness, worse visual acuity, higher DR severity. Conclusion: Patients with external PCPs, particularly those living farther from the clinic, experienced higher odds of lapses in DR care and presented with more severe eye disease. These patients may benefit from targeted care coordination or outreach to support adherence and earlier referrals for DR.