Individual and Systems-Based Risk Factors for Diabetic Vitrectomy in an Urban Safety-Net Hospital.

OBJECTIVE: To identify individual and systems-focused risk factors for pars plana vitrectomy among patients with proliferative diabetic retinopathy in the diverse, urban, safety-net hospital setting.

DESIGN: Single-center, retrospective, observational, case-control study at Zuckerberg San Francisco General Hospital and Trauma Center between 2017 and 2022.

SUBJECTS, PARTICIPANTS, AND CONTROLS: 222 patients with proliferative diabetic retinopathy over a 5-year span (2017-2022), consisting of 111 cases who underwent vitrectomy for vision-threatening complications (tractional retinal detachment, non-clearing vitreous hemorrhage, and neovascular glaucoma) and 111 controls with proliferative diabetic retinopathy with no history of vitrectomy or vision-threatening complications. Controls were matched 1:1 through incidence-density sampling.

METHODS, INTERVENTION, OR TESTING: Medical records were reviewed from time of entry into hospital system to vitrectomy date (or date-matched clinic visit for controls). Individual-focused exposures included age, gender, ethnicity, language, homelessness, incarceration, smoking status, area deprivation index, insurance status, baseline retinopathy stage, baseline visual acuity, baseline hemoglobin A1c, pan-retinal photocoagulation status, and cumulative anti-VEGF treatments. System-focused exposures included external department involvement, referral route, time within hospital and ophthalmology systems, interval between screening and ophthalmology appointment, interval between conversion to proliferative disease and pan-retinal photocoagulation or first treatment, and loss-to-follow-up in intervals of active proliferative disease.

MAIN OUTCOMES AND MEASURES: Odds ratios (OR) for each exposure on vision-threatening diabetic complications requiring vitrectomy.

RESULTS: The absence of pan-retinal photocoagulation was the primary significant individual-focused risk factor for vitrectomy in the multivariable analysis (OR 4.78, p=0.011). Systems-focused risk factors included longer interval between PDR diagnosis and initial treatment (weeks, OR 1.06, p=0.024) and greater cumulative duration of loss-to-follow-up during intervals of active PDR (months, OR 1.10, p=0.002). Greater duration in the ophthalmology system was the primary systems-focused protective factor against vitrectomy (years, OR 0.75, p=0.035).

CONCLUSIONS: Largely modifiable variables modulate risk for complications requiring diabetic vitrectomy. Each additional month of loss-to-follow-up for patients with active proliferative disease increased odds of vitrectomy by 10%. Optimizing modifiable factors to promote earlier treatment and maintain critical follow up in proliferative disease may reduce vision-threatening complications requiring vitrectomy in the safety-net hospital setting.