Identifying risk factors for severe diabetic eye disease

July 1, 2020

An analysis using a large commercial claims database found that almost 3% of patients developed severe diabetic eye disease within 5 years of being diagnosed with type 2 diabetes. Clinical and demographic risk factors were also identified.

This article was reviewed by William S. Gange, MD.

A retrospective study including a large patient sample shows that a small but significant proportion of individuals who are newly diagnosed with type 2 diabetes develop severe diabetic eye disease within 5 years.

According to the research, the risk for early development of this microvascular complication of diabetes is particularly high among patients with a history of renal disease, insulin use, A1c >9%, peripheral circulatory disease, neurologic disease, Black race, and advanced age at diagnosis.

“Currently, there are 30 million people with diabetes in the United States, and the number is expected to reach 40 million by 2030. As the population of diabetics continues to grow, screening all patients for diabetic eye disease at guideline-recommended intervals becomes a public health challenge,” said William S. Gange, MD, presenting the data at ARVO 2020.

“The findings of our study investigating risk factors for early development of severe diabetic eye disease can help to identify patients who are likely to benefit most from improved rates of screening,” Gange added.

Gange, resident USC Roski Eye Institute, Los Angeles, conducted the study with Brian Toy, MD, retina specialist and Assistant Professor of Clinical Ophthalmology, USC Roski Eye Institute, and faculty at the USC Schaeffer Center for Health Policy.

Employing a commercial claims database, they identified patients aged ≥18 years who were newly diagnosed with type 2 diabetes between 2007 and 2015 and who had at least 1 year of continuous enrollment preceding the diagnosis and a minimum of 2 years of continuing enrollment post-diagnosis.

Development of severe diabetic eye disease was identified by the presence of an ICD-9 or CPT code indicating a diagnosis of proliferative diabetic retinopathy, tractional retinal detachment, neovascular glaucoma, or blindness following the diagnosis of diabetes. Patients with any of these diagnoses prior to the initial diagnosis of diabetes were excluded.

The rate of development of the composite endpoint was analyzed at both 2 and 5 years post-diagnosis of diabetes. Patients included in the 5-year analysis had to have had at least 5 years of continuous enrollment after being diagnosed with diabetes.

For the 2-year risk analysis, 277,400 patients met the inclusion/exclusion criteria, of which approximately 4,000 (1.44%) developed severe diabetic eye disease by 2 years after their diabetes diagnosis. The 5-year analysis included approximately 71,000 patients, of which about 2,100 (2.91%) had developed severe diabetic eye disease.

“Proliferative diabetic retinopathy accounted for the majority of cases of severe diabetic eye disease, but a significant number of patients had developed blindness – 0.55% by 2 years and 1.18% by 5 years," Gange noted. "Tractional retinal detachment and neovascular glaucoma, however, were rare."

Comparisons between patients with and without severe diabetic eye disease showed a number of statistically significant differences between the two groups in demographic and clinical characteristics at 2 and 5 years.

However, several of the differences dropped out in the regression model.

The finding that individuals who were younger at diagnosis were less likely than their advanced age counterparts to have developed severe diabetic eye disease may seem counterintuitive knowing that the risk for diabetic eye disease increases with time since diagnosis and that patients diagnosed with diabetes at a younger age will go on to develop significant amounts of diabetic eye disease.

Gange explained, however, that the results of the study are understood by its design.

“Our study was based on longitudinal follow-up of patients that began at time of diagnosis," Gange said. "It is likely that patients who were older when diagnosed with diabetes had a longer duration of undiagnosed diabetes that would lead to higher rates of severe eye disease."

William S. Gange, MD
E: william.gange@med.usc.edu
This article was adapted from Gange’s presentation at the 2020 virtual meeting of the Association for Research in Vision and Ophthalmology. Gange did not indicate any proprietary interests relevant to the subject matter.