Diagnostic test accuracy using digital retinal imaging in the detection of any diabetic retinopathy by graders in Vietnam, against a reference standard from the UK

Purpose To compare the diagnostic test accuracy (DTA) of trained nurses, mid‐level and senior ophthalmologists in Vietnam against a reference standard from the UK, and assess the impact of further training on graders. Methods Fundus photographs were taken and graded at two different time points by trained nurses, mid‐level ophthalmologists and senior ophthalmologists in Vietnam using the UK National Screening Committee classification system. A reference standard from the UK regraded all images in masked fashion and DTA was calculated using sensitivity and specificity (with 95% CIs), and positive and negative predictive values. Results Between September and November 2018, 431 people with diabetes attended diabetic retinopathy (DR) screening in Southern Vietnam. The sensitivity for detecting any DR for all grader groups in Vietnam was low (<43%) against the reference standard in the UK. The sensitivity for detecting referable DR and referrable diabetic macular oedema was particularly low (<20%) for all grader groups. Subsequently, an additional subset of images from 138 consecutive patients screened from March to April 2021 was regraded in the UK to evaluate graders’ performance after additional training was delivered. A significant improvement in DTA among all grader groups in Vietnam was identified, with sensitivity for detecting any DR exceeding 85%. Nurses achieved the highest sensitivity for grading referable DR (76.9%, 60.3–88.3%) and mid‐level ophthalmologists attained the highest sensitivity for detecting referable maculopathy (77.5%, 61.2–88.6). Conclusions Grading accuracy was low in Vietnam in the first six months of implementing a training programme. Many factors may have contributed to poor grader performance, including inadequate training and feedback, insufficient time to participate in quality assurance testing and competing work responsibilities. After further training was delivered, DTA among all graders in Vietnam increased. Findings from this study are particularly important for DR programme planners in low‐ and middle‐income countries.