Individualized retinal exam schedules for screening of proliferative diabetic retinopathy or significant macular edema are recommended for patients with type 1 diabetes, according to research published in the New England Journal of Medicine.
Researchers from Massachusetts General Hospital and Harvard Medical School in Boston analyzed data from the Diabetes Control and Complications Trial (DCCT; ClinicalTrials.gov identifier: NCT00360893) and the Epidemiology of Diabetes Interventions and Complications (EDIC; ClinicalTrials.gov identifier: NCT00360815) follow-up study in which patients with diabetes were screened between 6 months and 4 years for proliferative retinopathy or clinically significant macular edema.
Patients in DCCT (n=1441) were between 13 and 39 years of age included in the trial between 1983 and 1989 who had been diagnosed with diabetes 1 to 5 years prior and had no baseline retinopathy, with a secondary group of 715 patients who had been diagnosed with diabetes 1 to 15 years prior with mild to moderate nonproliferative diabetic retinopathy.
Patients in the EDIC follow-up study (n=1375) were observed between 1983 and 2012, with a mean 23.5 years of follow-up data.
The researchers randomly assigned 711 patients in the DCCT study to receive an intensive intervention designed to lower glycemic levels to nondiabetic levels, while 730 patients underwent conventional therapy to reduce hyperglycemia and hypoglycemia. Patients underwent stereoscopic 7-field fundus photographs every 6 months in the DCCT study and every 4 years in the EDIC follow-up study.
Using a Markov model, the researchers estimated the probability that patients could go from state 1 (no retinopathy) or state 2 (mild noproliferative retinopathy) to state 5, which was classified as “proliferative diabetic retinopathy, clinically significant macular edema, or previous self-reported treatment with panretinal or focal photocoagulation, intraocular glucocorticoids, or anti-VEGF [anti-vascular endothelial growth factor] agents.”
“Progression from states 1 or 2 to state 5 retinopathy was unlikely over a period of 4 or more years, but progression was highly likely over shorter periods in patients with moderate (state 3) or severe (state 4) nonproliferative diabetic retinopathy,” the researchers wrote.
There was a 5% probability of progressing from state 1 to state 5 between retinal screenings at 4 years, with the same probability for patients progressing from state 2 to state 5 at 3 years, and 6 months in patients progressing from state 3 to state 5.
In patients with a glycated hemoglobin level of 6%, the probability of progressing to state 5 from state 1 over 5 years was 1.0%, whereas patients with a glycated hemoglobin level of 10% had a 4.3% probability over 3 years.
The researchers also noted eye exams decreased by 58% annually over a 20-year period using their schedule, reducing costs for patients.
“Our data suggest that a practical, evidence-based schedule for time to the next examination would be 4 years, 3 years, 6 months, and 3 months for patients with states 1 through 4, respectively, for which the corresponding cumulative incidence of progression to state 5 retinopathy would be 2.9%, 3.7%, 6.6%, and 14.4%,” they concluded.
Disclosures: Dr Hainsworth has stock options in Katalyst Surgical. The other researchers report no relevant financial disclosures.
Nathan DM, Bebu I, Hainsworth D, et al. Frequency of evidence-based screening for retinopathy in type 1 diabetes. N Engl J Med. 2017;376;1507-1516.. doi:10.1056/NEJMoa1612836