Global prevalence of diabetic retinopathy: protocol for a systematic review and meta-analysis

INTRODUCTION: With increasing diabetes trends worldwide, morbidity, mortality and associated costs due to diabetes-related complications are a global public health concern. Diabetic retinopathy (DR) is among the leading causes of vision loss at the global level; accurate estimates of DR burden is of crucial importance for planning, implementing and evaluating DR prevention and care interventions. The available evidence on DR prevalence at the global level, dating back to 2008, only considered data from selected regions. Taking into account the rapidly changing patterns in DR epidemiology, the aim of the current study is to carry out a systematic review and meta-analysis to derive solid and updated estimates on global and setting-specific DR prevalence. METHODS AND ANALYSIS: The systematic review methods have been defined following PRISMA guidelines. Studies published from 2008 through 2018 will be identified searching the electronic databases Embase, Medline, Cochrane, ISI Web of Knowledge, as well as through grey literature search. Retrieved records will be independently screened by two authors and relevant data will be extracted from studies reporting data on DR prevalence among individuals with diabetes. Prevalence pooled estimates of any form of DR and vision-threatening DR will be computed applying random-effects meta-analysis. Interstudy heterogeneity will be assessed using the I(2) statistic and explored through meta regressions and subgroup analyses. Depending on data availability, we plan to conduct subgroup analyses by study population, diabetes type, DR severity, geographical region and other selected clinical and sociodemographic variables of interest. Quality appraisal of the studies will be performed. ETHICS AND DISSEMINATION: Ethics approval is not required as this is a review of anonymised published data. Findings of the final report will be shared with the scientific community through publication in a peer-reviewed journal and presentation at conferences, as well as with key stakeholders, including national and international health authorities, health policy makers, healthcare professionals and the general population. CLINICAL TRIAL REGISTRATION: CRD42018085260.