Incidence and Progression of Diabetic Retinopathy in American Indian and Alaska Native Individuals Served by the Indian Health Service, 2015-2019

Abstract

Estimates of diabetic retinopathy (DR) incidence and progression in American Indian and Alaska Native individuals are based on data from before 1992 and may not be informative for strategizing resources and practice patterns. To examine incidence and progression of DR in American Indian and Alaska Native individuals. This was a retrospective cohort study conducted from January 1, 2015, to December 31, 2019, and included adults with diabetes and no evidence of DR or mild nonproliferative DR (NPDR) in 2015 who were reexamined at least 1 time during the 2016 to 2019 period. The study setting was the Indian Health Service (IHS) teleophthalmology program for diabetic eye disease. Development of new DR or worsening of mild NPDR in American Indian and Alaska Native individuals with diabetes. Outcomes were any increase in DR, 2 or more (2+) step increases, and overall change in DR severity. Patients were evaluated with nonmydriatic ultra-widefield imaging (UWFI) or nonmydriatic fundus photography (NMFP). Standard risk factors were included. The total cohort of 8374 individuals had a mean (SD) age of 53.2 (12.2) years and a mean (SD) hemoglobin A1c level of 8.3% (2.2%) in 2015, and 4775 were female (57.0%). Of patients with no DR in 2015, 18.0% (1280 of 7097) had mild NPDR or worse in 2016 to 2019, and 0.1% (10 of 7097) had PDR. The incidence rate from no DR to any DR was 69.6 cases per 1000 person-years at risk. A total of 6.2% of participants (441 of 7097) progressed from no DR to moderate NPDR or worse (ie, 2+ step increase; 24.0 cases per 1000 person-years at risk). Of patients with mild NPDR in 2015, 27.2% (347 of 1277) progressed to moderate NPDR or worse in 2016 to 2019, and 2.3% (30 of 1277) progressed to severe NPDR or worse (ie, 2+ step progression). Incidence and progression were associated with expected risk factors and evaluation with UWFI. In this cohort study, the estimates of DR incidence and progression were lower than those previously reported for American Indian and Alaska Native individuals. The results suggest extending the time between DR re-evaluations for certain patients in this population, if follow-up compliance and visual acuity outcomes are not jeopardized.