title: Observational studies in systematic [corrected] reviews of comparative effectiveness: AHRQ and the Effective Health Care Program.
abstract: OBJECTIVE
  Systematic reviewers disagree about the ability of observational studies to answer questions about the benefits or intended effects of pharmacotherapeutic, device, or procedural interventions. This study provides a framework for decision making on the inclusion of observational studies to assess benefits and intended effects in comparative effectiveness reviews (CERs).
  
  
  METHODS
  The conceptual model and recommendations were developed using a consensus process by members of the methods workgroup of the Effective Health Care Program of the Agency for Healthcare Research and Quality.
  
  
  RESULTS
  In considering whether to use observational studies in CERs for addressing beneficial effects, reviewers should answer two questions: (1) Are there gaps in the evidence from randomized controlled trials (RCTs)? (2) Will observational studies provide valid and useful information? The latter question involves the following: (a) refocusing the study questions on gaps in the evidence from RCTs, (b) assessing the risk of bias of the body of evidence of observational studies, and (c) assessing whether available observational studies address the gap review questions.
  
  
  CONCLUSIONS
  Because it is unusual to find sufficient evidence from RCTs to answer all key questions concerning benefit or the balance of benefits and harms, comparative effectiveness reviewers should routinely assess the appropriateness of inclusion of observational studies for questions of benefit. Furthermore, reviewers should explicitly state the rationale for inclusion or exclusion of observational studies when conducting CERs.
authors.affiliation: Department of Medical Informatics and Clinical Epidemiology, Oregon Health and Science University, Portland, OR 97239, USA. norriss@ohsu.edu
authors.forename: Susan L
authors.initials: SL
authors.lastname: Norris
authors.forename: David
authors.initials: D
authors.lastname: Atkins
authors.forename: Wendy
authors.initials: W
authors.lastname: Bruening
authors.forename: Steven
authors.initials: S
authors.lastname: Fox
authors.forename: Eric
authors.initials: E
authors.lastname: Johnson
authors.forename: Robert
authors.initials: R
authors.lastname: Kane
authors.forename: Sally C
authors.initials: SC
authors.lastname: Morton
authors.forename: Mark
authors.initials: M
authors.lastname: Oremus
authors.forename: Maria
authors.initials: M
authors.lastname: Ospina
authors.forename: Gurvaneet
authors.initials: G
authors.lastname: Randhawa
authors.forename: Karen
authors.initials: K
authors.lastname: Schoelles
authors.forename: Paul
authors.initials: P
authors.lastname: Shekelle
authors.forename: Meera
authors.initials: M
authors.lastname: Viswanathan
mesh_terms: D015982:Bias; D057186:Comparative Effectiveness Research / Q000379:methods*; D032921:Consensus; D003657:Decision Making; D019317:Evidence-Based Medicine / Q000379:methods; D006078:Government Programs; D006801:Humans; D019370:Observation; D017063:Outcome Assessment, Health Care / Q000379:methods; D016032:Randomized Controlled Trials as Topic; D012196:Review Literature as Topic; D014481:United States; D016270:United States Agency for Healthcare Research and Quality