Critical evaluation of the Newcastle-Ottawa scale for the assessment of the quality of nonrandomized studies in meta-analyses
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The quality assessment of non-randomized studies is an important component of a thorough meta-analysis of non-randomized studies. Low quality studies can lead to a distortion of the summary effect estimate. Recent guidelines for the reporting of meta-analyses of observational studies recommend the assessment of the study quality (MOOSE) . In principal, three categories of quality assessments tools are available: scales, simple checklists, or checklists with a summary judgment (for details see Sanderson et al. 2007 ). The results of the quality assessment can be used in several ways such as forming inclusion criteria for the meta-analysis, informing a sensitivity analysis or meta-regression, weighting studies, or highlighting areas of methodological quality poorly addressed by the included studies . It has been criticized that the use of summary scores involve inherent weighting of component items including items that may not be related to the validity of the study findings ....
KeywordsUveal Melanoma Cohort Member Nurse Health Study Quality Item Response Proportion
I am very grateful for many helpful comments by an anonymous reviewer on an earlier version of this manuscript.
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