Newcastle-Ottawa Scale: comparing reviewers’ to authors’ assessments

BMC Medical Research Methodology

Mark Loeb¹  Dominik Mertz³  Carson Ka-Lok Lo² 

[1] Department of Pathology and Molecular Medicine, McMaster University, MDCL 3203, 1200 Main St W, Hamilton, Ontario L8N 3Z5, Canada;Department of Medicine, University of Toronto, Toronto Ontario, Canada;Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton Ontario, Canada

关键词: Observational studies;    Risk of bias;    Validity;    Reliability;    Inter-rater;    Newcastle Ottawa Scale;   

Others  :  866371
DOI  :  10.1186/1471-2288-14-45

 received in 2013-10-07, accepted in 2014-03-17,  发布年份 2014

【 摘 要 】

Background

Lack of appropriate reporting of methodological details has previously been shown to distort risk of bias assessments in randomized controlled trials. The same might be true for observational studies. The goal of this study was to compare the Newcastle-Ottawa Scale (NOS) assessment for risk of bias between reviewers and authors of cohort studies included in a published systematic review on risk factors for severe outcomes in patients infected with influenza.

Methods

Cohort studies included in the systematic review and published between 2008–2011 were included. The corresponding or first authors completed a survey covering all NOS items. Results were compared with the NOS assessment applied by reviewers of the systematic review. Inter-rater reliability was calculated using kappa (K) statistics.

Results

Authors of 65/182 (36%) studies completed the survey. The overall NOS score was significantly higher (p < 0.001) in the reviewers’ assessment (median = 6; interquartile range [IQR] 6–6) compared with those by authors (median = 5, IQR 4–6). Inter-rater reliability by item ranged from slight (K = 0.15, 95% confidence interval [CI] = −0.19, 0.48) to poor (K = −0.06, 95% CI = −0.22, 0.10). Reliability for the overall score was poor (K = −0.004, 95% CI = −0.11, 0.11).

Conclusions

Differences in assessment and low agreement between reviewers and authors suggest the need to contact authors for information not published in studies when applying the NOS in systematic reviews.

【 授权许可】

   
2014 Lo et al.; licensee BioMed Central Ltd.