Burden of diabetic retinopathy in mainland China: Protocol for an updated systematic review and meta-analysis of prevalence and risk factors to identify prevention policies

BACKGROUND: Diabetic retinopathy (DR) is the leading cause of vision loss in adults of working age. Although existing systematic reviews of the prevalence of DR for mainland China have been reported, but several studies have been newly reported. Further some potential factors for DR are still discrepant and inconclusive. The aim of current research is to identify relevant literature regarding the prevalence of DR and DR-related factors in mainland China. In addition, we will project the number of individuals affected with DR in mainland China in years 2030 and 2050. METHODS: This systematic review will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. To identify publications in English or Chinese languages on the prevalence of DR in mainland China, a comprehensive step-by-step search of the PubMed, Embase, Web of Science, VIP Chinese Periodical, and China National Knowledge Infrastructure (CNKI) databases will be performed. Two reviewers will independently review the studies for eligibility according to the predefined inclusion and exclusion criteria. The quality of the included studies will be evaluated according to the National Health Institute Quality Assessment tool and Quality Assessment Manual. A random-effect model (DerSimonian-Laird method) will be used for the meta-analysis. Heterogeneity and publication bias among studies will be estimated by the I(2) statistic and Begg funnel plot, respectively. RESULTS: This systematic review study will provide an evidence of prevalence, risk factors, and national burden for DR in mainland China. CONCLUSION: The study will give an explicit evidence to provide preventative measures of DR. PROSPERO registration number: CRD42018094565.