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

This 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). A 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 (κ) and standard error (SE) were utilized. The 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 (κ = 0.31; 95% confidence interval [CI], 0.23-0.40) in comparison with the WHO (κ = 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 (κ = 0.44; 95% CI, 0.31-0.57) compared to the WHO (κ = 0.25; 95% CI, 0.11-0.39). Our 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.