Quality Assessment of Systematic Reviews 
and Meta-analyses on Biomarkers in Oral Squamous Cell Carcinoma.

PURPOSE: To examine the methodological quality of systematic reviews (SR) and meta-analyses on biomarkers in oral squamous cell carcinoma (OSCC) using validated checklists. MATERIALS AND METHODS: A systematic literature search was performed to identify SR and meta-analyses focusing on biomarkers in OSCC published between January 1990 and March 2014. Details of the relevant aspects of methodology as reported in these SR were extracted from the full text publications. The methodological quality of these SR and meta-analyses was evaluated using the AMSTAR and Glenny checklists. RESULTS: After screening 1098 abstracts from the electronic database, seven studies were included in quality assessment. The mean AMSTAR score of all SR was 4.6 +/- 1.9 of a possible 11 (range: 2-7) and the mean score of all SR using the checklist devised by Glenny et al was 7.1 +/- 1.6 of a possible 14 (range: 5-9). Spearman correlation analysis revealed that AMSTAR and Glenny scores were highly correlated (rs = 0.757; p = 0.049). The methodological quality in journals with an impact factor above 2.5 (AMSTAR: p = 0.031; Glenny: p = 0.046) was significantly higher. In addition, in SR published after 2007, higher AMSTAR and Glenny scores were noted; however, this was not statistically significant (AMSTAR: p = 0.076; Glenny: p = 0.232). CONCLUSIONS: Systematic reviews and meta-analyses on biomarkers in OSCC presented marked methodological and structural variability, which elevates the risk of bias and hence invalid conclusions. Checklists such as AMSTAR or Glenny may improve quality and uniformity of SR, and would thus also increase the clinical validity and applicability of SR.