Protocol and registration
This review was conducted in accordance with the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines and has been registered in the International Prospective Register of Systematic Reviews (PROSPERO; registration number: CRD42021275084).
Computer retrieval of The Cochrane Library (Issue 2, 2013), PubMed, and Embase. Clinical studies related to THE diagnosis of NAFLD by VAI were searched from database establishment to September 2021. Keywords were combined with free words for retrieval. English search terms include Nonalcoholic Steatohepatitis, nonalcoholic fatty liver disease, metabolic associated fatty liver disease (MAFLD), NASH, NAFLD, MAFLD, Visceral adiposity index, VAI.
Inclusion and exclusion criteria
Two evaluators independently screened literature, extracted data, and evaluated the methodological quality of the included studies according to the inclusion and exclusion criteria. In case of disagreement, the dispute shall be settled through discussion or adjudicated by a third party. The inclusion criteria were as follows: (1) Published diagnostic studies of VAI in diagnosing NAFLD, And it is a primary or original study; (2) The study population consisted of hospitalized patients who received final imaging or pathological diagnosis. Sample size 30 or more. The true positive value (TP), false positive value (FP), false negative value (FN), and true negative value (TN) were provided or can be calculated statistically; (3) The test to be evaluated is VAI, and the imaging results or pathological results are the gold standards; (4) Sensitivity (Sen), specificity (Spe), positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and Subject operating Characteristic curve (SROC) and area under the curve (AUC) were calculated. The exclusion criteria were: (1) conference report; (2) Missing important data reports or unclear measurement indicators. (3) Published repeatedly in different journals, When two studies in the same institution reported the same target outcome, the quality of inclusion was better; (4) only those studies whose title was related to VAI diagnosis of NAFLD, but not related to VAI diagnosis of NAFLD.
Data extraction and quality assessment
Two independent investigators reviewed the full-text articles. The included items were evaluated as yes, no, or uncertain. Inter-researcher disagreements were resolved by consensus, or by a third investigator. Data extraction table was developed to extract data, which mainly included: the purpose of extraction was usually the general information of the study (document number, document title, year, author, statistical method), the information of patients (gender, age, etc.), and the quality evaluation of the literature. Then, the methodological quality of the included studies was evaluated according to the quadAS-2 tool developed by Whiting et al. to evaluate the quality of diagnostic studies.
RevMan 5.3 and Meta-Disc 1.4 software were used for analysis. Spearman correlation analysis was used to investigate whether there was a threshold effect, and the SROC curve was summarized to determine whether the SROC pattern was "shoulder and arm shape". Corran-q test and I2 test were used to analyze the heterogeneity among the included studies. Appropriate models were selected according to the heterogeneity (if P > 0.05 and I2 < 50%, the fixed-effects model was used for meta-analysis; otherwise, a random-effects model was used for meta-analysis). Z-test was used to analyze the area under the SROC curve among subgroups, and the one-by-one exclusion method was used for sensitivity analysis to evaluate the stability of the study results. Stata 16.0 software was used to draw Deek’s funnel plot to evaluate publication bias, and Fagan plot was used to evaluate the diagnostic ability of VAI. P < 0.05 was considered statistically significant.
Patient and public involvement
No patients or the public were involved in the research.
Ethics approval statement
This study did not involve human participants.