Impact of Social Vulnerability Index on the Development of Severe Visual Impairment or Blindness from Glaucoma

Abstract

PurposeTo evaluate whether geocoded social risk factor data predict the development of severe visual impairment or blindness due to glaucoma during follow-up using a large electronic health record (EHR) database. DesignCohort study. MethodsPatients diagnosed with open-angle glaucoma (OAG) at a tertiary care institution. All eyes had glaucomatous visual field defects at baseline. Sociodemographic and ocular data were extracted from EHR, including age, gender, self-reported race and ethnicity, insurance status, OAG type, prior glaucoma laser or surgery, baseline disease severity using Hodapp-Anderson-Parrish criteria, mean intraocular pressure (IOP) during follow-up, and central corneal thickness. Social vulnerability index (SVIndex) data at the census tract level were obtained using geocoded patient residences. Mixed-effects Cox proportional hazard models were completed to assess for the development of severe visual impairment or blindness during follow-up, defined as BCVA ≤20/200 at the last two clinic visits or standard automated perimetry (SAP) mean deviation (MD) ≤-22dB confirmed on two tests. ResultsA total of 4,046 eyes from 2,826 patients met inclusion criteria and were followed for an average of 4.3±2.2 years. Severe visual impairment or blindness developed in 79 eyes (2.0%) from 76 patients (2.7%) after an average of 3.4±1.8 years, leading to an incidence rate of severe visual impairment or blindness of 0.5% per year. Older age (adjusted hazards ratio (HR) 1.36 per decade, p=0.007), residence in areas with higher SVIndex (HR 1.56 per 25% increase, p<0.001), higher IOP during follow-up (HR 3.01 per 5 mmHg increase, p<0.001), and moderate or severe glaucoma at baseline (HR 7.31 and 26.87, p<0.001) were risk factors for developing severe visual impairment or blindness. Concordance index of the model was 0.87. Socioeconomic, minority status/language, and housing type/transportation SVIndex themes were key contributors to developing severe visual impairment or blindness. ConclusionsRisk factors for developing glaucoma-related severe visual impairment or blindness included older age, elevated IOP during follow-up, moderate or severe disease at baseline, and residence in areas associated with greater social vulnerability. In addition to ocular risk factors, geocoded EHR data regarding social risk factors could help identify patients at high risk of developing glaucoma-related visual impairment.