Inter-grader reliability in the Danish screening programme for diabetic retinopathy.

Area of Science:

• Ophthalmology
• Medical Imaging
• Public Health

Background:

• The Danish Registry of Diabetic Retinopathy (DR) monitors over 200,000 patients.
• DR screening is conducted by ophthalmologists for uncomplicated type 2 diabetes and at hospitals for type 1 and complicated type 2 diabetes.

Purpose of the Study:

• To assess the clinical reliability of retinal images from Danish DR screening facilities.
• To evaluate the inter-grader agreement between primary screening ophthalmologists and certified graders.

Main Methods:

• Retinal images from 230 patients were collected from screening facilities nationwide.
• Primary graders estimated DR levels (0-4) using the International Clinical Diabetic Retinopathy scale.
• A blinded, certified secondary grader re-evaluated the images, with agreement assessed using weighted kappa analysis.

Main Results:

• Overall agreement between primary and secondary graders was 93% (κ=0.83).
• Agreement varied by screening facility type: 96% (κ=0.89) for ophthalmologists and 90% (κ=0.76) for hospitals.
• The distribution of DR levels reported by primary graders was 0: 66.8%, 1: 12.2%, 2: 13.1%, 3: 1.3%, and 4: 5.5%.

Conclusions:

• A high overall inter-grader agreement was observed in the Danish DR screening program.
• Findings support the reliability of DR gradings within the national screening program.
• The study indicates that reported DR gradings accurately reflect patient conditions.