Second, the methodological quality criteria applied in our meta-analysis had been developed and applied in previous meta-analyses by Huebner et al. [ 3], Gould et al. [ 4], Delgado-Bolton et al. [ 5] and Schwimmer et al. [ 6].
Furthermore, the methodological quality criteria applied in our meta-analysis include certain guidelines and items not analysed or incomplete in the QUADAS criteria, such as: description of study design and patient selection criteria, characteristics of patient population finally studied, sensitivity and specificity data, and change in management information.
The aim of this review was to re-search the literature, add at least one new study, and apply methodological quality filters in a sensitivity analysis to test the strength of the conclusion that mucolytics are beneficial in watchful waiting for glue ear.
These methodological quality recommendations should only be applied to population-based studies and address issues of coverage, bias, completeness and accuracy.
As such, a generic methodological quality tool was developed and applied to all of the included studies, regardless of study design using a similar format that was used in a previous systematic review [ 34].
Two investigators (XW and ZYL) independently evaluated the methodological quality of each study by applying with the diagnostic accuracy tool Quality Assessment of Diagnostic Accuracy Studies (QUADAS) [ 28], which is recommended by the Cochrane Collaboration for the quality assessment of diagnostic studies.
To assess the methodological quality of the included studies, we applied the same criteria as a recent Cochrane review [20].
Since no guidelines concerning the reporting of indirect comparisons and assessment methods exist, the importance of a review of the reporting and methodological quality of the indirect comparison methods applied in published reviews is clear.
To evaluate the methodological quality of the research studies, we applied the SIGN system [ 29].
For the evaluation of the methodological quality of the included SRs, we applied the eleven-item AMSTAR tool due to its reliability, construct validity and feasibility [ 9- 11].
