Critical evaluation of the Newcastle-Ottawa scale for the assessment of the quality of nonrandomized studies in meta-analyses

The quality assessment of non-randomized null is an important component of a thorough meta-analysis of nonrandomized studies. Low quality null can lead to a distortion of the summary effect estimate. Recent guidelines for the reporting of meta-analyses of observational null recommend the assessment of the study quality (MOOSE) [1]. In principal, three categories of quality assessments tools are available: scales, simple checklists, or checklists...