title: Systematic reviews supporting practice guideline recommendations lack protection against bias.
abstract: OBJECTIVE
  To evaluate the quality of systematic reviews (SRs) affecting clinical practice in endocrinology.
  
  
  METHODS
  We identified all SRs cited in The Endocrine Society's Clinical Practice Guidelines published between 2006 and January 2012. We evaluated the methodological and reporting quality of the SRs in duplicate using the Assessment of Multiple Systematic Reviews (AMSTAR) tool. We also noted if the guidelines recommendations that are clearly supported by SRs acknowledged their quality.
  
  
  RESULTS
  During the 5-year period of study, endocrine guidelines cited 69 SRs. These SRs had a mean AMSTAR score of 6.4 (standard deviation, 2.5) of a maximum score of 11, with scores improving over time. SRs of randomized trials had higher AMSTAR scores than those of observational studies. Low-quality SRs (methodological AMSTAR score 1 or 2 of 5, n = 24, 35%) were cited in 24 different recommendations and were the main evidentiary support for five recommendations, of which only one acknowledged the quality of SRs.
  
  
  CONCLUSIONS
  Few recommendations in endocrinology are supported by SRs. The quality of SRs is suboptimal and is not acknowledged by guideline developers.
authors.affiliation: Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: Juan P
authors.initials: JP
authors.lastname: Brito
authors.forename: Apostolos
authors.initials: A
authors.lastname: Tsapas
authors.forename: Marcio L
authors.initials: ML
authors.lastname: Griebeler
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.forename: Gabriela J
authors.initials: GJ
authors.lastname: Prutsky
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Domecq
authors.forename: M Hassan
authors.initials: MH
authors.lastname: Murad
authors.forename: Victor M
authors.initials: VM
authors.lastname: Montori
mesh_terms: D015982:Bias; D002985:Clinical Protocols / Q000592:standards; D004704:Endocrinology / Q000592:standards*; D019317:Evidence-Based Medicine; D006801:Humans; D017410:Practice Guidelines as Topic; D012107:Research Design / Q000592:standards*; D012196:Review Literature as Topic