Is Binary Grading Better Than WHO System for Grading Epithelial Dysplasia? A Systematic Review and Meta-Analysis

BackgroundThis meta-analysis summarizes the current evidence on the intra- and inter-observer agreement between WHO and the binary grading systems used to assess epithelial dysplasia (ED).MethodsA systematic search for observational studies that compared the level of agreement among pathologists between WHO and binary grading systems for ED was conducted using three databases: Medline, Scopus, and EBSCOhost. For the meta-analysis, summary estimations of kappa value (kappa) and standard error (SE) were utilized.ResultsThe pooled analysis of observations by 46 pathologists from a total of eight studies showed better interobserver agreement in the interpretation of ED for the binary system (kappa = 0.31; 95% confidence interval [CI], 0.23-0.40) in comparison with the WHO (kappa = 0.14; 95% CI, 0.10-0.19). The intra-observer agreement was reported only by five studies and was also found to be higher for the binary system (kappa = 0.44; 95% CI, 0.31-0.57) compared to the WHO (kappa = 0.25; 95% CI, 0.11-0.39).ConclusionsOur results validate that the binary system has better overall intra-observer and interobserver agreement than the WHO system. Further studies with larger cohorts are mandatory before clinically relevant conclusions are drawn, as evidence remains inadequate.