S J Aldington

Delay in diabetic retinopathy screening increases the rate of detection of referable diabetic retinopathy.

To assess whether there is a relationship between delay in retinopathy screening after diagnosis of Type 2 diabetes and level of retinopathy detected.

The use of statistical methodology to determine the accuracy of grading within a diabetic retinopathy screening programme

We aimed to use longitudinal data from an established screening programme with good quality assurance and quality control procedures and a stable well‐trained workforce to determine the accuracy of grading in diabetic retinopathy screening.

Risk stratification for diabetic eye screening.

To the Editor : In the August issue of this journal Looker et al presented results from data analyses of patients from the Scottish Diabetic Retinopathy Screening programme [1]. The principal finding was that transition rates to referable diabetic eye disease were lowest among people with type 2 diabetes and who had had two consecutive screens showing no visible retinopathy. We had already published this result in Diabetes Care [2], online in November 2012 and in print in March 2013 but this has not been acknowledged by Looker et al. We recognise that our results were based on data from patients for whom we had no information on the type of diabetes, but they would predominantly have been patients with type 2 diabetes because they were from a populationbased screening programme in England. The transition rates found in the Scottish study are of the same order as those found in our cohort. The authors state that a major strength of the paper is that it uses a centralised quality-controlled grading system and the criteria for referable disease have not altered over the course of the programme. This tends to suggest a single reading centre although they have not expressly stated this. However, Goatman et al [3] reported in 2012 on external quality assurance (EQA) of grading in the Scottish programme in nine reading centres. They reported that there were significant differences in sensitivities and specificities between graders and between reading centres in 2008, when much of the data in the Looker paper would have been collected. This is not alluded to in the Looker paper [1]. The authors discuss several possible reasons for the apparent regression of mild background retinopathy to no visible retinopathy at subsequent examination. However, they do not raise the possibility that this may be due to changes in grading or the differences in sensitivity and specificity between graders enumerated in the EQA paper [3]. These recent results suggest that a 2 year screening interval may be safe in those with type 2 diabetes and no visible retinopathy on two consecutive screens. In our paper [2] this may be deduced from the results. However we also discuss the quality of our grading and the need to validate these results in other populations before implementation of changes in screening intervals. There is no ‘gold standard’ for grading of digital retinal images and hence the introduction of extended intervals in any programme would require validation of any rules in existing datasets, continuing education of graders and robust failsafe procedures, EQA and QA of grading.

Updating Diabetic Retinopathy Screening Lists using Automatic Extraction from GP Patient Records

Objectives Diabetic Retinopathy screening services aim to reduce the risk of sight loss amongst patients with diabetes. The rising incidence of diabetes in England and the operational need to ensure the accuracy and timeliness of screening lists led to a pilot study of electronic extraction of data from primary care. This study aimed to evaluate the effectiveness of updating the single collated list of patients eligible for diabetic eye screening using extracts from electronic patient records in primary care. Setting and Methods The Gloucestershire Diabetic Eye Screening Programme (GDESP) provides screening for 85 General Practices in the county. Of these, 54 using Egton Medical Information Systems (EMIS) practice management system software agreed to participate in this study. The screening list held in 2009 by the Gloucestershire DESP of 14,209 patients known to have diabetes was audited against a list created with automatic extraction from General Practice records of patients marked with the diabetes Read Code C10. Those subsequently screened and referred to the Hospital Eye service were followed up. Results The Gloucestershire DESP manual list covering the 54 EMIS practices comprised 14,771 people with diabetes. The audit process identified an additional 709 (4.8%) patients coded C10, including 23 diagnosed more than 5 years ago, and 20 patients under the age of 20 who were diagnosed more than a year ago. Conclusion Automatic extraction of data from General Practice identified 709 patients coded as having diabetes not previously known to the Gloucestershire DESP.