Coverage in screening for diabetic retinopathy according to screening provision: results from a national survey in England and Wales

Aim To assess the proportion of people with diabetes screened for retinopathy according to provision of screening services. Methods Twenty-five health authorities in England and Wales were sampled after stratification by type of screening provision for diabetic retinopathy. Nine did not have a population-based screening scheme, six had an optometry scheme, six had a camera scheme and four had schemes with more than one method of screening ('mixed schemes'). Within each authority general practices were randomly sampled, 129 in total, and in each the records of a sample of diabetic patients examined. Results Of the 9200 records examined, 5812 (63.2%) had a record of one or more retinal examinations from any source in the year before the survey. This proportion did not differ significantly according to type of screening provision. The proportion of people with one or more retinal examinations by an 'expert' (defined as ophthalmologist, diabetologist, optometrist or screening scheme) in the last year was 44.7% where there was no screening scheme and 62.2%, 59.4%, and 61.6%, respectively, where optometry, camera and mixed schemes were present. Adjusted relative odds (95% confidence interval) for a retinal examination from any source in the last year compared with areas with no screening schemes were 1.19 (0.73, 1.93), 1.26 (0.80, 1.98), and 1.19 (0.77, 1.84) for camera, optometry and mixed schemes, respectively. Equivalent figures for an expert retinal examination were 2.30 (1.51, 3.49), 1.86 (1.25, 2.78) and 2.13 (1.32, 3.45). Coverage by schemes themselves did not differ according to type of scheme. Highest coverage rates, including examinations by screening schemes, were achieved in those treated with insulin, and the lowest rates found in those treated with diet alone. Conclusions Screening schemes have had a small impact on overall retinal examinations, but a higher impact on the coverage of examinations performed by experts.