title: A comprehensive appraisal of meta-analyses focusing on nonsurgical treatments aimed at decreasing perioperative mortality or major cardiac complications.
abstract: OBJECTIVE
  Millions of patients worldwide who undergo surgical procedures face significant morbidity and mortality risks. Several systematic reviews have been performed on ancillary treatments aimed at improving surgical outcomes, but their features and scholarly impact are unclear. We describe characteristics of meta-analyses on ancillary treatments aimed at improving surgical outcomes and explore factors associated with scholarly citations.
  
  
  METHODS
  Systematic reviews published up to 2008 were searched without language restrictions in MEDLINE/PubMed. Reviews focusing on nonsurgical treatments aimed at decreasing mortality or major cardiac complications were included. Associations between content, quality, and bibliometric details and scholarly citations in several indexes were systematically appraised.
  
  
  RESULTS
  From 2,239 citations, 84 systematic reviews were identified. Patients most commonly underwent cardiovascular surgery (40.2%), and were tested for cardiovascular drugs (25.8%), with placebo acting as control (38.1%). Internal validity appeared largely robust, as most (50.5%) reviews were at low risk of bias. Normalized yearly citations for the included reviews ranged between 5.6 in Google Scholar and 4.3 in Web of Science. Multivariable analysis showed that citations were significantly and positively associated with number of authors, North American corresponding author, number of studies included, number of patients included, noncardiothoracic surgical scope, explicit funding, and lack of competing interests (all p < 0.05).
  
  
  CONCLUSIONS
  Systematic reviews currently represent a key element in defining state of the art ancillary treatments of patients undergoing surgery. However, the citation success of available meta-analyses is not significantly associated with prognostically relevant findings or quality features.
authors.affiliation: Department of Anesthesia and Intensive Care, Università Vita-Salute San Raffaele, Milan, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Zambon
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Biondi-Zoccai
authors.forename: Elena
authors.initials: E
authors.lastname: Bignami
authors.forename: Laura
authors.initials: L
authors.lastname: Ruggeri
authors.forename: Alberto
authors.initials: A
authors.lastname: Zangrillo
authors.forename: Giovanni
authors.initials: G
authors.lastname: Landoni
mesh_terms: D000758:Anesthesia / Q000009:adverse effects; D015706:Bibliometrics; D006331:Heart Diseases / Q000401:mortality* / Q000517:prevention & control*; D006801:Humans; D007431:Intraoperative Complications / Q000401:mortality* / Q000517:prevention & control*; D015201:Meta-Analysis as Topic; D019990:Perioperative Care / Q000379:methods* / Q000706:statistics & numerical data; D059035:Perioperative Period / Q000401:mortality*; D011183:Postoperative Complications / Q000401:mortality* / Q000517:prevention & control*; D017594:Publication Bias; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results