Oral Epithelial Dysplasia Grading Systems: A Systematic Review & Meta-Analysis

This systematic review and meta-analysis aims to provide a robust qualitative and quantitative analysis of the different systems used to assess the grade of oral epithelial dysplasia (OED). This study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyzes (PRISMA) statement. Six electronic databases were searched for primary research published over the past four decades. Overall quality and level of evidence were based on the Johns Hopkins Research Evidence Appraisal Tool, while evidence of heterogeneity was determined by the Q-statistic and I^2 statistic. Evidence of publication bias was determined using Egger's regression and the Rank correlation tests. A total of 170 records were identified. Only 9 primary research articles were included in the qualitative systematic review. Four studies (4/9) were included in the final quantitative meta-analysis. The grading systems analyzed included the WHO, binary, Ljubljana, Smith and Pindborg, Brothwell, and the oral intraepithelial neoplasia. The results demonstrate the binary system to be superior to the WHO system in grading OED, by providing better inter-observer agreement, however, the substantial error among the inter-observer κ values analyzed indicates the significance of this finding to be of minimal impact. Lack of reliable reproducibility of the grading systems and lack of common effect size (heterogeneity analysis) were noted.