Systematic review and meta-analysis of diagnostic accuracy of detection of any level of diabetic retinopathy using digital retinal imaging

Abstract

BackgroundVisual impairment from diabetic retinopathy (DR) is an increasing global public health concern, which is preventable with screening and early treatment. Digital retinal imaging has become a preferred choice as it enables higher coverage of screening. The aim of this review is to evaluate how different characteristics of the DR screening (DRS) test impact on diagnostic test accuracy (DTA) and its relevance to a low-income setting.MethodsWe conducted a systematic literature search to identify clinic-based studies on DRS using digital retinal imaging of people with DM (PwDM). Summary estimates of different sub-groups were calculated using DTA values weighted according to the sample size. The DTA of each screening method was derived after exclusion of ungradable images and considering the eye as the unit of analysis. The meta-analysis included studies which measured DTA of detecting any level of DR. We also examined the effect on detection from using different combinations of retinal fields, pupil status, index test graders and setting.ResultsSix thousand six hundred forty-six titles and abstracts were retrieved, and data were extracted from 122 potentially eligible full reports. Twenty-six studies were included in the review, and 21 studies, mostly from high-income settings (18/21, 85.7%), were included in the meta-analysis. The highest sensitivity was observed in the mydriatic greater than two field strategy (92%, 95% CI 90–94%). The highest specificity was observed in greater than two field methods (94%, 95% CI 93–96%) where mydriasis did not affect specificity. Overall, there was no difference in sensitivity between non-mydriatic and mydriatic methods (86%, 95% CI 85–87) after exclusion of ungradable images. The highest DTA (sensitivity 90%, 95% CI 88–91%; specificity 95%, 95% CI 94–96%) was observed when screening was delivered at secondary/tertiary level clinics.ConclusionsNon-mydriatic two-field strategy could be a more pragmatic approach in starting DRS programmes for facility-based PwDM in low-income settings, with dilatation of the pupils of those who have ungradable images. There was insufficient evidence in primary studies to draw firm conclusions on how graders’ background influences DTA. Conducting more context-specific DRS validation studies in low-income and non-ophthalmic settings can be recommended.Electronic supplementary materialThe online version of this article (10.1186/s13643-018-0846-y) contains supplementary material, which is available to authorized users.

<p>The Evolution of Diabetic Retinopathy Screening Programmes: A Chronology of Retinal Photography from 35 mm Slides to Artificial Intelligence</p>

“…The sensitivity and specificity for the detection of referrable disease was highest in three field CFP (92% and 96%), followed by two field CFP (96% and 89%) and was lowest in singlefield CFP (78% and 86%). [44][45][46][47] The sensitivity and specificity of two mydriatic 45°CFP, the first centered at the macula and the second on the optic disc, has been shown to be 80.2% and 96.2%, respectively. 48 Despite the superior diagnostic accuracy of multiple field CFP, acquisition needs to be balanced with the greater focus on patient collaboration, resource and training.…”

Effectiveness of task-shifting for the detection of diabetic retinopathy in low- and middle-income countries: a rapid review protocol.

“…The quality of the screening is measured by the diagnostic test accuracy (DTA) of the method of choice in the hands of non-ophthalmologists. 18 It is recommended that population-based screening programmes should reach over 80% sensitivity and 95% specificity. 6,19 Screening performed by photographers has been shown to be more accurate when done by photographers with specialist medical or eye care qualifications.…”

“…20 There is also evidence that non-medical retinal image graders can achieve the threshold level of sensitivity and specificity in both mydriatic and non-mydriatic retinal assessment. 18 Secondly, the screening technique used can also affect the DTA. The recommended technique is photographybased screening which adds the possibility of quality assurance.…”

“…However, in many clinics without cameras other methods of retinal examination that are not necessarily effective as screening techniques are still used. 18 The sensitivity of direct ophthalmoscopy in detecting DR is low (65%) and indirect ophthalmoscopy requires extensive training and experience. 21 Slit lamp bio-microscopy has a high sensitivity and specificity but also requires significant training and the availability of a slit lamp.…”

“…Outreach services delivered by non-ophthalmologists can be an answer to this problem, but must ensure that DTA is maintained. 18,20 Evidence suggests that DTA is higher in hospital-based screening services compared with outreach services. 16 Several approaches for DR screening in outreach services that can lend themselves to task-shifting have shown promising accuracy levels.…”