Umbrella review is a third study conducted through evidence synthesis method, based on the secondary studies including systematic reviews and meta-analyses. Although it has been widely used abroad, further understanding, recommendation and application of this type of method are still limited in China. We introduced the definition, objective, present application, the similarities and differences with systematic reviews or meta-analyses, indications, limitations, and research progress of umbrella review in the research area of traditional Chinese medicine (TCM), aiming to benefit future clinical research and treatment in practice.
Umbrella review is a research method that comprehensively analyzes the systematic reviews and meta-analysis of a research question. In recent years, the research methods of umbrella review have been widely used, but the quality of umbrella review is uneven. Therefore, this paper focuses on the production methods and existing challenges of umbrella review, in order to provide references for domestic researchers to make umbrella review.
Objective To overview the systematic reviews/meta-analysis (SR/MA) for the effectiveness of yoga on patients with type 2 diabetes mellitus. Methods The CNKI, WanFang Data, VIP, CBM, PubMed, Cochrane Library, Embase, Web of Science, JBI and CINAHL databases were electronically searched to collect SR/MA on the intervention of yoga in diabetes mellitus from inception to November 6th, 2023. Two researchers independently screened the literature and extracted data. AMSTAR was used to evaluate the quality of methodology, and GRADE was used to evaluate the certainty of evidence, and the outcome indicators were statistically analyzed. Results A total of 14 SR/MA were included. The evaluation results of AMSTAR showed that 7 articles were of high quality and 7 articles were of moderate quality. The result of GRADE showed that there were 2 items of high-level evidence, 26 items of intermediate evidence, and the remaining 31 items were low-level or very low-level evidence. The results showed that yoga could significantly reduce fasting blood glucose (FBG) (moderate confidence), glycosylated hemoglobin (HA1C) (moderate confidence) and postprandial blood glucose (PPBG) levels (moderate confidence), and was also superior to other interventions in high-density cholesterol (HDL) (moderate confidence), low-density cholesterol (LDL) (moderate confidence), triglyceride (TG) (moderate confidence), total cholesterol (TC) (moderate confidence), systolic blood pressure (SBP) and diastolic blood pressure (DBP) (moderate confidence), muscle strength (high confidence), cardiorespiratory fitness (moderate confidence) and weight (moderate confidence). Conclusion The existing evidence shows that yoga has a good effect on blood glucose control (moderate confidence) and also has a certain effect on lipid parameters (moderate confidence) and anthropometric indicators (moderate confidence), but the quality and confidence of the current research evidence are low. Future researchers should standardize the research design to provide more high-quality evidence for the prognosis and treatment of type 2 diabetes mellitus.
The overlap of literature in umbrella reviews can affect the reliability and accuracy of research conclusions, leading to results with a higher risk of bias. Therefore, it becomes crucial to assess the degree of overlapping and how to handle it. In order to avoid redundant calculations and reduce the risk of bias, researchers need to quantify the degree of literature overlap and adopt corresponding processing strategies. This paper provides a detailed introduction to the calculation methods of overlapping and different strategies for handling overlapping, aiming to provide a reference and guidance for domestic scholars' understanding and application of this method.
Objective To overview the systematic review (SR) of the effects of dietary pattern intervention during pregnancy on pregnant women with gestational diabetes mellitus (GDM). Methods The Cochrane Library, The Joanna Briggs Institute Library, Embase, PubMed, Web of Science, CINAHL, CBM, CNKI, WanFang Data, and VIP database were electronically searched to collect SR and meta-analysis on the effects of different dietary patterns on maternal and infant outcomes of gestational diabetes mellitus from inception to October 1, 2024. Two reviewers independently screened literature, extracted data, and then AMSTAR 2 tool was used to assess the methodological quality of included studies. Meta-analysis performed by using RevMan 5.3 software. Results A total of 15 relevant SR were included, the methodological quality of the included SR was generally low, with 3 SR at a low level and 12 SR at a very low level. Major dietary patterns include the low glycemic index (GI) diet, carbohydrate (CHO) restricted diet, energy restricted diet, dietary approaches to stop hypertension (DASH) diet, high-fiber diet, polyunsaturated fatty acid (PUFA) rich diet, soy protein-enriched diet, low glycemic load (GL) diet, and mediterranean diet. A meta-analysis of primary outcome measures showed that the low GI diet, DASH diet and low GL load diet had a lower incidence of blood glucose levels and adverse pregnancy outcomes (including maternal weight gain, insulin use, cesarean section, macrosomia, newborn birth weight) compared with the control diets. Conclusion It was recommended that GDM pregnant women follow the low GI diet, DASH diet, or low GL diet to control blood glucose levels and improve pregnancy outcomes. There is currently insufficient evidence to support the effects of other dietary patterns on GDM.