Sensitivity and specificity of a new scoring system for diabetic macular oedema detection using a confocal laser imaging system

Abstract

AIM To assess the use of the Heidelberg retina tomograph (HRT) in screening for sight threatening diabetic macular oedema in a hospital diabetic clinic, using a new subjective analysis system (SCORE).

METHODS 200 eyes of 100 consecutive diabetic patients attending a diabetologist's clinic were studied, all eyes had an acuity of 6/9 or better. All patients underwent clinical examination by an ophthalmologist. Using the HRT, one good scan was obtained for each eye centred on the fovea. A System for Classification and Ordering of Retinal Edema (SCORE) was developed using subjective assessment of the colour map and the reflectivity image. The interobserver agreement of using this method to detect macular oedema was assessed by two observers (ophthalmic trainees) who were familiarised with SCORE by studying standard pictures of eyes not in the study. All scans were graded from 0–6 and test positive cases were defined as having a SCORE value of 0–2. The sensitivity of SCORE was assessed by pooling the data with an additional 88 scans of 88 eyes in order to reduce the confidence interval of the index.

RESULTS 12 eyes in eight out of the 100 patients had macular oedema clinically. Three scans in three patients could not be analysed because of poor scan quality. In the additional group of scans 76 out of 88 eyes had macular oedema clinically. The scoring system had a specificity of 99% (95% CI 96–100) and sensitivity of 67% (95% CI 57–76). The predictive value of a negative test was 87% (95% CI 82–99), and that of a positive test was 95% (95% CI 86–99). The mean difference of the SCORE value between two observers was –0.2 (95% CI –0.5 to +0.07).

CONCLUSIONS These data suggest that SCORE is potentially useful for detecting diabetic macular oedema in hospital diabetic patients.