Point of Care Retinopathy Screening Study (PARROTS)

Burgess, Philip

Point of Care Retinopathy Screening Study (PARROTS)

Date

2020-06-05

Authors

Burgess, Philip

Publisher

Kamuzu University of Health Sciences

Abstract

Type of study A pilot of point of care cross-sectional (POC) screening for diabetic retinopathy (DR) delivered by ophthalmic clinical officers (OCOs) and optometrists will be undertaken at Queen Elizabeth Central Hospital and Chiradzulu District Hospital. This study will investigate both the accuracy of the screening test and acceptability of the system of POC screening to patients and health care workers. The Problem Malawi has an adult population prevalence of diabetes of approximately 5% and a high prevalence of sight threatening diabetic retinopathy (STDR) in persons attending diabetes clinics. Visual loss from diabetes is preventable and treatable. Early detection is key but European style screening programmes would not be cost-effective or sustainable in Malawi. Low-cost fundus cameras used together with novel automated grading software could provide the means to provide effective point-of-care screening by health workers. Recent work in 2018/2019 has been undertaken to assess the quality of retinal photographs produced by 2 portable fundus cameras and to investigate the accuracy of an automated grading algorithm used together with a hand-held fundus camera for detection of DR. Automated grading addresses the problems of recruiting, training and cost for human grading of retinal photographs. A POC result overcomes the problem of communicating results at a distance. The planned next stage of this project is described below. Objectives Broad Objectives 1. To determine whether new and low cost portable screening cameras alongside a grading algorithm for diabetic retinopathy will benefit patients with diabetes Specific objectives 1. To investigate the accuracy of an automated grading algorithm used together with a low-cost fundus camera for detection DR which imminently threatens vision in 2 settings: a Central Hospital and a District Hospital. 2. To investigate the acceptability to patients of a system of POC DR screening using an automated grading algorithm used together with a low-cost fundus camera. 3. To investigate the acceptability to health care workers of a system of POC DR screening using an automated grading algorithm used together with a low-cost fundus camera This is a prospective pilot study of a screening intervention based at 2 sites. People living with diabetes (PLWD) attending a diabetes clinic at each site (n=246) will be recruited. DR screening with POC automated grading will be delivered by OCOs and optometrists. Digital fundus photography of 2 standard fields (disc-centred and macula-centred) will be performed through dilated pupils using 2 hand-held fundus cameras (Volk Pictor Plus and Volk InView). Photographs will be analysed using Eye Star automated grading software. Screen positive cases (DR which imminently threatens vision: LDES level 50+ and exudates within 500um of the central fovea) will be referred to a tertiary referral centre: Lions Sight First Eye Unit at Queen Elizabeth Central Hospital, Blantyre for assessment and, if necessary, treatment. All screen positive subjects will be examined by an ophthalmologist (PK) to determine the positive predictive value. A proportion of screen negative subjects will be examined by an ophthalmologist to determine the negative predictive value. The acceptability of the intervention will be assessed by qualitative methods. All patients and health care workers will be invited to complete a questionnaire. A sub-group of patients (n=28) and health care workers (n=10) will be interviewed. A separate sub-group of patients will be invited to participate in focus groups (n=20). The impact of distance, gender, and risk perception on acceptability of the POC DR screening to patients will be assessed. The study will be undertaken in a sequential manner: phase 1 at Queen Elizabeth Central Hospital; phase 2 at Chiradzulu District Hospital. After phase 1 of the study, a planned interim analysis will be undertaken, and any necessary changes made to the screening model. Expected results The results are expected to demonstrate the effectiveness of screening for sight threatening diabetic retinopathy using handheld cameras in a LMIC hospital setting. Results will also establish acceptability for patients and health care staff. Data from this pilot study will inform future large studies of this intervention. If the expected results are seen, implementing diabetic retinopathy screening at a district level would be sought. Approval would be sought for deployment of the fundus cameras and grading system at a national level, from the appropriate governing body. Dissemination of results The findings of the study will be disseminated through presentation at national and international meetings and through peer reviewed publication. The Committee of Medical Research and Ethics Committee (COMREC) will be notified of the findings in the first instance. Findings from the study will inform a phased introduction of diabetic retinopathy screening throughout Malawi.