An evidence mapping study based on systematic reviews of TCM for diabetic retinopathy

Abstract Background: Diabetic retinopathy (DR) is a severe microvascular complication of diabetes mellitus, posing a significant risk of vision impairment and blindness among the diabetic population. With the global prevalence of diabetes rising, the burden of DR is expected to increase, necessitating effective prevention and treatment strategies. Traditional Chinese Medicine (TCM) has been increasingly explored as a complementary and alternative treatment for DR. Systematic reviews have been conducted to evaluate the efficacy and safety of TCM interventions for DR, but the evidence remains scattered and varied in quality. An evidence mapping study can provide a comprehensive overview of the available systematic reviews, identify gaps in the evidence, and highlight areas needing further research, thereby informing clinical practice and guiding future research endeavors in the field of TCM for diabetic retinopathy. Objective: This study aims to evaluate the reporting and methodological quality of systematic reviews (SRs) investigating the use of Traditional Chinese Medicine (TCM) for the treatment of diabetic retinopathy (DR), and to analyze the effectiveness, methodological quality, and classification of TCM treatment methods for DR using an evidence-mapping approach. Methods: A comprehensive literature search was conducted in major biomedical databases to identify relevant SRs published up to November 2023. The reporting quality of the included SRs was assessed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, while the methodological quality was evaluated using the Assessment of Multiple Systematic Reviews 2 (AMSTAR 2) tool. Results: A total of 51 SRs, encompassing 131,084 participants, met the eligibility criteria and were included in the analysis. The evidence mapping indicated that TCM is a relatively effective therapy for treating DR. However, the quality of the methodology and reporting in these SRs was suboptimal. The analysis revealed that while many SRs satisfied key AMSTAR criteria, significant methodological shortcomings were present, such as insufficient information on funding, lack of lists of excluded studies, and absence of pre-specified protocols. Furthermore, common reporting deficiencies included incomplete protocol and registration details, unexplained review rationales, and insufficient relevant outcome data from other analyses. Conclusion: TCM appears to be a relatively effective therapy for treating DR. However, the reporting and methodological quality of SRs on TCM for DR is generally low, highlighting the need for improvement and more high-quality evidence. Future SRs should strive to adhere to established reporting guidelines, address the identified methodological weaknesses, and enhance the overall quality of evidence regarding TCM interventions for DR. Adhering to PRISMA and AMSTAR 2 guidelines is essential to improve the quality of future SRs.