Disparities in screening, diagnosis, treatment, and outcomes for diabetic retinopathy among people with lived experience of homelessness in Canada: results from a matched longitudinal cohort study

Objective — To estimate the rates of screening, diagnosis, treatment, and outcomes related to diabetic retinopathy among persons with diabetes who have experienced homelessness compared with a matched cohort of nonhomeless controls.

Methods — A propensity score-matched cohort study was conducted using administrative health data from Ontario. Eligible persons required a diagnosis of diabetes and at least 1 hospital encounter between April 2006 and March 2019. Homeless status was determined using a validated algorithm that identified whether individuals were homeless at the time of any acute care encounter during the study period. Each person who experienced homelessness was matched to a nonhomeless control based on sociodemographic and clinical characteristics. Rate ratios (RR) and differences in proportions were calculated for screening, diagnosis, and treatment of diabetic retinopathy, as well as for the outcome of vision loss using generalized linear models with a negative binomial distribution and robust standard errors.

Results — 1,069,493 people met the inclusion criteria, of which, 6 944 had a history of homelessness. A suitable nonhomeless match was found for 5 712 individuals. The rate of diabetic retinopathy screening was lower in those with a history of homelessness when compared to controls (RR = 0.75; 95% CI: 0.72–0.78), while the rate of having billing codes representing diabetic retinopathy was higher (RR = 1.42; 95% CI: 1.02–1.97). There was no significant difference in rates of treatment or vision loss.

Conclusions — The disparities in rates of screening and diagnosis of diabetic retinopathy in those with lived experience of homelessness presents an area for targeted interventions to improve health outcomes in this population.