Comparison of Newcastle Ottawa scale (NOS) and Agency for Health Research and Quality (AHRQ) as risk of bias assessment tools for cohort studies

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Singh M1, Kaur J2, Singh S3, Thumburu KK3, Jaiswal N4, Chauhan A5, Agarwal A5, Paul N2, Sagwal S2
1Department of Pediatrics and ICMR Advanced Center for Evidence-Based Child Health, Advanced Pediatric Centre, PGIMER , India, 2ICMR Advanced Center for Evidence-Based Child Health, Advanced Pediatric Centre, PGIMER , India, 3ICMR Advanced Center for Evidence-Based Child Health, Advanced Pediatric Centre, PGIMER, India, 4Department of Pediatrics and ICMR Advanced Center for Evidence-Based Child Health, Advanced Pediatric Centre, PGIMER , India, 5ICMR Advanced Center for Evidence-Based Child Health, Advanced Pediatric Centre, PGIMER , India

Background: At present there are few validated scales for risk of bias assessment in systematic reviews of cohort studies. We have attempted to compare the Newcastle Ottawa scale (NOS) and Agency for Health Research and Quality (AHRQ) for a systematic review on cohort studies correlating childhood anthropometric measures and adult non communicable diseases.

Objectives: To compare the Newcastle Ottawa scale (NOS) and Agency for Health Research and Quality (AHRQ) as risk of bias assessment tools for cohort studies.

Methods: We have compared the above two risk of bias assessment tools for a systematic review aimed at evaluating the association of childhood anthropometric measures and adult cardiovascular morbidity and mortality. The NOS contains eight items that are designed to assess cohort studies on the basis of selection of cohorts, comparability of cohorts and assessment of exposure and outcome. The AHRQ risk of bias assessment tool contains eight items that assess selection, detection, attrition, selective reporting bias, and bias due to confounding. An overall score was generated for each study based on the number of items identified as having a low risk of bias.

Results: Two reviewers independently scored ten studies with the two tools and calculated the inter-observer variability (kappa) score to be 95%. The NOS and AHRQ have significant overlaps but the NOS included additional points about the duration of length of follow-up and whether the outcome assessed w

Conclusions: Both the tools have scored similar results, but performing quality assessment by NOS was simpler.

Acknowledgment: The study was supported by ICMR, India and World Health Organization, Geneva, Switzerland