Grading systems of oral cavity pre-malignancy: a systematic review and meta-analysis.

PURPOSE: Oral potentially malignant disorders (OPMDs) may have varying degrees of oral epithelial dysplasia (OED). Traditional grading schemes separate OED into three-tiers (mild, moderate, and severe). Alternatively, a binary grading system has been previously proposed that stratifies OED into low-risk and high-risk categories based on a quantitative threshold of dysplastic pathologic characteristics. This systematic review evaluates the predictive value of a binary OED grading system and examines agreement between pathologists. METHODS: This meta-analysis queried 4 databases (PubMed, Ovid-MEDLINE, Cochrane, and SCOPUS) and includes 4 studies evaluating binary OED grading systems. Meta-analysis of proportions and correlations was performed to pool malignant transformation rates (MTR), risk of malignant transformation between OED categories, and measures of interobserver agreement. RESULTS: Pooled analysis of 629 lesions from 4 different studies found a six-time increased odds of malignant transformation in high-risk lesions over low-risk lesions [odds ratio (OR) 6.14, 95% 1.18-15.38]. Reported ORs ranged from 2.8 to 22.4. The overall MTR was 26.8%, with the high-risk and low-risk lesions having MTRs of 57.9% (95% CI 0.386-0.723) and 12.7% (95% CI - 0.210 to 0.438), respectively. Pooled unweighted interobserver kappa values for the binary grading system and three-tiered system were 0.693 (95% CI 0.640-0.740) and 0.388 (95% CI 0.195-0.552), respectively. CONCLUSION: Binary grading of OED into low-risk and high-risk categories may effectively determine malignant potential, with improved interobserver agreement over three-tiered grading. Improved grading schemes of OED may help guide management (watchful waiting vs. excision) of these OPMDs.