Similarities, reliability and gaps in assessing the quality of conduct of systematic reviews using AMSTAR-2 and ROBIS: systematic survey of nutrition reviews.

BACKGROUND: AMSTAR-2 ('A Measurement Tool to Assess Systematic Reviews, version 2') and ROBIS ('Risk of Bias in Systematic Reviews') are independent instruments used to assess the quality of conduct of systematic reviews/meta-analyses (SR/MAs). The degree of overlap in methodological constructs together with the reliability and any methodological gaps have not been systematically assessed and summarized in the field of nutrition. METHODS: We performed a systematic survey of MEDLINE, EMBASE, and the Cochrane Library for SR/MAs published between January 2010 and November 2018 that examined the effects of any nutritional intervention/exposure for cancer prevention. We followed a systematic review approach including two independent reviewers at each step of the process. For AMSTAR-2 (16 items) and ROBIS (21 items), we assessed the similarities, the inter-rater reliability (IRR) and any methodological limitations of the instruments. Our protocol for the survey was registered in PROSPERO (CRD42019121116). RESULTS: We found 4 similar domain constructs based on 11 comparisons from a total of 12 AMSTAR-2 and 14 ROBIS items. Ten comparisons were considered fully overlapping. Based on Gwet's agreement coefficients, six comparisons provided almost perfect (> 0.8), three substantial (> 0.6), and one a moderate level of agreement (> 0.4). While there is considerable overlap in constructs, AMSTAR-2 uniquely addresses explaining the selection of study designs for inclusion, reporting on excluded studies with justification, sources of funding of primary studies, and reviewers' conflict of interest. By contrast, ROBIS uniquely addresses appropriateness and restrictions within eligibility criteria, reducing risk of error in risk of bias (RoB) assessments, completeness of data extracted for analyses, the inclusion of all necessary studies for analyses, and adherence to predefined analysis plan. CONCLUSIONS: Among the questions on AMSTAR-2 and ROBIS, 70.3% (26/37 items) address the same or similar methodological constructs. While the IRR of these constructs was moderate to perfect, there are unique methodological constructs that each instrument independently addresses. Notably, both instruments do not address the reporting of absolute estimates of effect or the overall certainty of the evidence, items that are crucial for users' wishing to interpret the importance of SR/MA results.