title: Systematic review and evidence integration for literature-based environmental health science assessments.
abstract: BACKGROUND
  Systematic-review methodologies provide objectivity and transparency to the process of collecting and synthesizing scientific evidence in reaching conclusions on specific research questions. There is increasing interest in applying these procedures to address environmental health questions.
  
  
  OBJECTIVE
  The goal was to develop a systematic-review framework to address environmental health questions by extending approaches developed for clinical medicine to handle the breadth of data relevant to environmental health sciences (e.g., human, animal, and mechanistic studies).
  
  
  METHODS
  The Office of Health Assessment and Translation (OHAT) adapted guidance from authorities on systematic-review and sought advice during development of the OHAT Approach through consultation with technical experts in systematic review and human health assessments, as well as scientific advisory groups and the public. The method was refined by considering expert and public comments and through application to case studies.
  
  
  CONCLUSIONS
  Here we present a seven-step framework for systematic review and evidence integration for reaching hazard identification conclusions: 1) problem formulation and protocol development, 2) search for and select studies for inclusion, 3) extract data from studies, 4) assess the quality or risk of bias of individual studies, 5) rate the confidence in the body of evidence, 6) translate the confidence ratings into levels of evidence, and 7) integrate the information from different evidence streams (human, animal, and "other relevant data" including mechanistic or in vitro studies) to develop hazard identification conclusions.
  
  
  CONCLUSIONS
  The principles of systematic review can be successfully applied to environmental health questions to provide greater objectivity and transparency to the process of developing conclusions.
authors.affiliation: Office of Health Assessment and Translation, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Rooney
authors.forename: Abee L
authors.initials: AL
authors.lastname: Boyles
authors.forename: Mary S
authors.initials: MS
authors.lastname: Wolfe
authors.forename: John R
authors.initials: JR
authors.lastname: Bucher
authors.forename: Kristina A
authors.initials: KA
authors.lastname: Thayer
mesh_terms: D000818:Animals; D006801:Humans; D004782:Environmental Health / Q000379:methods; D019317:Evidence-Based Medicine; D014481:United States; D000078202:Systematic Reviews as Topic
references.citation: J Clin Epidemiol. 2011 Apr;64(4):401-6
references.pmid: 21208779
references.citation: Cochrane Database Syst Rev. 2009 Jan 21;(1):MR000006
references.pmid: 19160345
references.citation: J Clin Epidemiol. 2010 May;63(5):491-501
references.pmid: 19540721
references.citation: J Epidemiol Community Health. 2011 May;65(5):392-5
references.pmid: 20947872
references.citation: Crit Rev Toxicol. 2013 Oct;43(9):753-84
references.pmid: 24040995
references.citation: Environ Health Perspect. 2003 Oct;111(13):A696-8
references.pmid: 14570029
references.citation: Environ Health Perspect. 1998 Oct;106(10):A480-3
references.pmid: 9755148
references.citation: Health Aff (Millwood). 2011 May;30(5):931-7
references.pmid: 21555477
references.citation: J Clin Epidemiol. 2011 Dec;64(12):1283-93
references.pmid: 21839614
references.citation: J Clin Epidemiol. 2009 Oct;62(10):e1-34
references.pmid: 19631507
references.citation: Environ Health Perspect. 2011 May;119(5):A196-7
references.pmid: 21531652
references.citation: Birth Defects Res B Dev Reprod Toxicol. 2005 Feb;74(1):9-16
references.pmid: 15729730
references.citation: Environ Health Perspect. 2013 Apr;121(4):A108-9
references.pmid: 23548834
references.citation: Birth Defects Res B Dev Reprod Toxicol. 2005 Feb;74(1):1-8
references.pmid: 15729732
references.citation: J Clin Epidemiol. 2011 Apr;64(4):407-15
references.pmid: 21247734
references.citation: BMJ. 2012 Jan 03;344:d7762
references.pmid: 22214758
references.citation: Proc R Soc Med. 1965 May;58:295-300
references.pmid: 14283879
references.citation: BMJ. 1997 Sep 13;315(7109):640-5
references.pmid: 9310565
references.citation: J Clin Epidemiol. 2011 Dec;64(12):1277-82
references.pmid: 21802904
references.citation: J Clin Epidemiol. 2011 Dec;64(12):1303-10
references.pmid: 21802903
references.citation: J Clin Epidemiol. 2009 Oct;62(10):1006-12
references.pmid: 19631508
references.citation: J Clin Epidemiol. 2011 Apr;64(4):383-94
references.pmid: 21195583