An evaluation of diabetic retinopathy screening models

The aim of the study was to evaluate three models of diabetic retinopathy screening in a North London Health Authority so as to advise on setting up a comprehensive screening programme. The study evaluated the models against their own objectives and standards published by the British Diabetic Association (BDA) and the Royal Colleges for diabetic retinopathy screening, and assessed service user and provider satisfaction.

Methods used were: analysis of the patient database and a case note review on uptake and coverage; follow-up for abnormal findings; comparisons of positive predictive values; postal questionnaire survey of service user satisfaction; semi-structured interviews of service providers.

A total of 2230 people with diabetes were screened between March 1998 and August 2000. The general practitioner (GP) led model achieved 63 per cent coverage and the two optometrist models 24 per cent. The detection rate for sight-threatening diabetic retinopathy was 6 per cent and 2.5 per cent for the optometrists and GP models, respectively. Positive predictive values of 94 per cent, 90 per cent and 60 per cent, respectively, were established for the GP-led model, the optometrists using the retinal camera and the optometrists using indirect ophthalmoscopy only. Twenty-eight (45 per cent) of the 62 people with sight-threatening diabetic retinopathy failed to attend for further investigation. Service user and service provider satisfaction were high for all three models.

The evaluation confirmed that all three methods of screening provided an effective service. The implementation of a district-wide diabetic retinopathy screening programme requires the establishment of a systematic call and recall system to achieve attendance for screening. A formal follow-up of people referred for specialist assessment and treatment should be part of the service.