Study highlights the role of demographic and socioeconomic characteristics as contributors to disease- and treatment-related disparities among patients with diabetic macular edema.
This article was reviewed by Rishi P. Singh, MD.
A retrospective cohort study characterizing presenting disease-related features, treatment, and outcomes of patients with diabetic macular edema (DME) reinforces the existence of racial/ethnic and socioeconomic health care disparities in the US population.
The research, which was presented by Rishi P. Singh, MD, at the 2020 virtual meeting of the American Academy of Ophthalmology, was conducted to understand how presenting visual acuity and diabetic retinopathy severity differ among patients receiving anti-VEGF injections for DME and to characterize associations between socioeconomic factors and anti-VEGF injection utilization and visual acuity outcomes.
The analyses showed that Hispanic/Latino ethnicity and Medicaid insurance were strongly associated with worse presenting visual acuity at diagnosis. Factors associated with receipt of a higher number of anti-VEGF injections over time were non-Hispanic ethnicity, private insurance status, and white race. Non-Hispanic ethnicity and private insurance status also correlated with better long-term visual acuity outcomes.
“Our study’s results are consistent with those of some previous studies, including an analysis of patients at Cole Eye Institute,” said Singh, a retina specialist at Cole Eye Institute, Cleveland Clinic, and Associate Professor of Ophthalmology, Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio. “While we think the natural history of DME is influenced by glycemic control, the time since diabetes diagnosis, and ophthalmic interventions, we are realizing from the accumulating research that it is far more complex. Rather, patient outcomes depend on multiple inter-related factors, including health care access, disease burden, and racial and social factors.”
Identification of the disparities provides a foundation for further research and efforts to rectify the issues.
“We are hoping to improve physician understanding of the social determinants of health and barriers to care to develop appropriate treatment plans for at-risk populations," Singh said. "In addition, we would like to expand our research to examine other factors as possible predictors of anti-VEGF injection utilization, including education, HbA1c level, smoking status, distance to clinic, and racial-ethnic biases in health care settings.
"Furthermore, we recognize the need to characterize literacy among patient populations and with regards to the ophthalmic interventions as a means to identify opportunities for improving access to regular anti-VEGF injections for at-risk populations," Singh added.
The retrospective cohort study searched the IRIS Registry to identify adults (age >18 years) diagnosed with treatment-naive DME receiving their first anti-VEGF injection.
A total of 203,673 patients met the eligibility criteria, of which a majority (51%) resided in the southern United States. The patients had an average age of 60 years and were nearly equally represented by males and females. Approximately 50% of the population had diabetic retinopathy, and the largest proportion of patients with diabetic retinopathy had proliferative disease. Baseline visual acuity for the entire population was approximately 66 ETDRS letters.
Analyses looking at correlates with diabetic retinopathy severity showed it was worse among black/African American patients versus whites, Hispanic/Latinos versus non-Hispanic/non-Latinos, and among patients with Medicaid versus those having private insurance.
Factors associated with better visual acuity at presentation included younger age and male gender. Again, there were statistically significant differences favoring whites versus black/African American patients, non-Hispanic/non-Latinos versus Hispanics/Latinos, and patients having private insurance versus Medicaid as well as those with Medicare coverage versus Medicaid. Analyses comparing patients with mild nonproliferative diabetic retinopathy against those with either severe nonproliferative disease or proliferative disease showed that patients having the worse level of diabetic retinopathy also had worse presenting visual acuity.
Visual acuity at presentation among non-Hispanic patients was similar across all geographic regions, defined as Midwest, Northeast, South, and West. However, geographic disparity in visual acuity at presentation was noted among Hispanic patients and patients with Medicaid as their primary insurance. For both analyses, visual acuity was worse among residents in southern versus northern states.
“In particular, our study showed that visual acuity at presentation was lower among Hispanics and those living in the Sunbelt states where diabetes prevalence is very high,” Singh said.
Analyses of anti-VEGF injection utilization showed that overall, patients received approximately 3.8 injections during the first year after their diagnosis. Significant differences in anti-VEGF injection utilization showed higher utilization among white non-Hispanics versus white Hispanics, Medicare and private insurance patients versus Medicaid patients, and those with less severe versus more severe retinopathy. In addition, patients living in the southern and western regions of the US received a higher number of injections on average than their counterparts in other areas of the country.
The study also evaluated factors associated with differences in visual acuity during 5 years of follow-up. These analyses showed that compared with white patients, blacks had worse visual acuity at baseline and throughout the duration of follow-up.
Disparity also existed between Hispanic and non-Hispanic patients with Hispanics presenting with and maintaining worse visual acuity throughout the study, and the difference between Hispanic and non-Hispanic patients was even greater than the disparity between blacks and whites. Patients with more severe diabetic retinopathy at baseline also maintained worse vision throughout follow-up compared with their less severely affected counterparts.
An analysis with patients stratified by insurance status showed all groups maintained the same mean visual acuity throughout follow-up. The best average visual acuity was found among private insurance patients, followed by those with Medicare coverage while those with Medicaid had the worst visual acuity.
Interestingly, however, when patients were stratified by race/ethnicity and insurance status, Hispanic patients with private insurance had worse visual acuity at presentation and at 5 years than non-Hispanic Medicaid patients, Singh noted.