Indian Health Service Sees DR Success

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Over the past 30 years, there has been a notable decline in the incidence and progression of diabetic retinopathy (DR) in American Indian and Alaska Native individuals, researchers report.¹

The decline coincides with the success of Indian Health Service (IHS) diabetes-related programs, particularly the teleophthalmology program for di­abetic eye disease, noted Dara Shahon, MD, at the Phoenix Indian Medical Center in Arizona. And it raises the possibility of extending the follow-up interval for selected individuals.

GAINS. The rates of DR incidence and progression among those served by the IHS are now comparable to estimates of non–American Indian and non–Alaska Native populations examined in the last 20 years.

A retrospective cohort study. The researchers analyzed medical records of 8,374 individuals with diabetes who were seen for a baseline appointment and at least one follow-up visit between Jan. 1, 2015, and Dec. 31, 2019. At base­line, patients at 75 IHS primary clinics in 20 states either had no evidence of DR or had mild nonproliferative dia­betic retinopathy (NPDR).

Of these patients, 18% had mild NPDR or worse at follow-up; 6.2% had an increase of 2 or more steps in DR over time; and .1% developed prolif­erative diabetic retinopathy (PDR). Of new DR cases, 65.5% were mild NPDR. Of those with mild NPDR at baseline, 27.2% developed a more severe DR level, with 2.3% progressing to severe NPDR or worse.

Who progressed? Characteristics associated with DR incidence, as well as occurrence of a ≥2 step increase in DR level, included diabetes duration of 15 or more years, a higher HbA1c level, and diabetes therapy (including diet, insulin, or combination treatment).

Regarding the latter, patients on in­sulin had 4.5 times the rate of a ≥2 step increase in DR, compared to patients on diet therapy alone. Notable charac­teristics associated with any progres­sion from mild NPDR included longer diabetes duration, higher HbA1c level, and presence of peripheral neuropathy.

Imaging mattered. Eyes were imaged nonmydriatically with either ultra-widefield (UWF) imaging or digital fundus photography. Although the study did not conduct a head-to-head comparison of the two modalities, it found that patients imaged with fundus photography at baseline and UWF at follow-up had 2.2 times the rate of a ≥2 step increase in DR level compared to patients imaged with fundus photog­raphy only at both stages. This finding may reflect the ability of UWF to iden­tify predominantly peripheral lesions.

While the researchers were unable to comment on the superiority of one imaging modality or the other, Dr. Sha­hon said, “We are quite pleased” with the low rate of UWF images deemed ungradable.

No changes to protocol. The find­ings suggest a possibility of extending follow-up intervals from yearly to alter­nate years for certain low-risk patients. This would conform to the American Diabetes Association’s biennial fol­low-up protocol,² but it runs contrary to the Academy’s guidelines.³

However, any change in protocol would require further evaluation, said Dr. Shahon, who is currently study­ing adherence to teleophthalmology recommendations for follow-up care and regular screening. Potential candi­dates for less frequent follow-up would include those who have no NPDR at baseline, are imaged consistently with UWF, and adhere to current screening recommendations, Dr. Shahon said. She added that HbA1c results and cardio­vascular status must also be considered.

For now, she stressed the value of teleophthalmology for assessing how patient populations change. “Rates do change over time and need to be up-dated.”

—Miriam Karmel

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1 Fonda SJ et al. JAMA Ophthalmol. Published online March 9, 2023.

2 Solomon SD et al. Diabetes Care. 2017;40(3):412-418.

3 Flaxel CJ et al. Ophthalmology. 2020;127(1):P66-P145.

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Relevant financial disclosures: Dr. Shahon—None.

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