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25-10-2018 | Ophthalmology | News | Article

Moderate agreement shown between ETDRS 7- and ultrawide-field imaging for DR

medwireNews: Agreement between Early Treatment Diabetic Retinopathy Study (ETDRS) 7-field imaging and ultrawide-field (UWF) imaging is moderate when assessing the severity of diabetic retinopathy (DR) in patients with type 1 or type 2 diabetes, US research shows.

However, the degree of concordance between the two techniques increased substantially following open adjudication of known discrepancies by two masked graders, Isoken Odia (Jaeb Center for Health Research, Tampa, Florida) and colleagues report in JAMA Ophthalmology.

Overall, 742 eyes with both ETDRS 7-field images and UWF images masked to contain only the ETDRS 7-field area were included in the study and graded to one of eight severity levels ranging from no DR to high-risk proliferative DR.

Of these, 48.4% showed exact agreement between the ETDRS 7-field and masked UWF images and 88.0% agreed within one step, giving a weighted κ statistic of 0.51, which indicates moderate agreement.

The researchers note that there were 130 (17.0%) eyes with discrepancies of two or more severity grades between the techniques. Of these, 116 were adjudicated side-by-side by a senior grader who had not previously seen the images to determine the reasons for the discrepancies.

Following this open adjudication, 59% of images had perfect agreement and 96.9% had agreement within one severity grade, resulting in a weighted κ statistic of 0.77 indicating substantial agreement between the two methods.

Grading errors and suboptimal imaging quality of one or the other technique were the main reasons for the initial discrepancies among the adjudicated images, with suboptimal image quality equally distributed between the two modalities.

When the team compared UWF masked images with unmasked images, they found that the severity of DR matched exactly in 86.3% of eyes but was more severe by at least one step in the UWF unmasked images in 12.5% of eyes.

In addition, analysis of the unmasked UWF images showed that the lesions were predominantly peripheral in 41.0% of eyes, with 11.0% having DR that was graded two or more steps more severe on the unmasked UWF images.

“Whether identification of these peripheral lesions will substantially affect the ability to assess the risk of future DR progression awaits final data from this ongoing study”, Odia et al remark.

They conclude that their findings “could justify UWF imaging for assessing DR severity end points in future studies.”

By Laura Cowen

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