title: Systematic reviews of observational studies of risk of thrombosis and bleeding in urological surgery (ROTBUS): introduction and methodology.
abstract: BACKGROUND
  Pharmacological thromboprophylaxis in the peri-operative period involves a trade-off between reduction in venous thromboembolism (VTE) and an increase in bleeding. Baseline risks, in the absence of prophylaxis, for VTE and bleeding are known to vary widely between urological procedures, but their magnitude is highly uncertain. Systematic reviews and meta-analyses addressing baseline risks are uncommon, needed, and require methodological innovation. In this article, we describe the rationale and methods for a series of systematic reviews of the risks of symptomatic VTE and bleeding requiring reoperation in urological surgery.
  
  
  METHODS
  We searched MEDLINE from January 1, 2000 until April 10, 2014 for observational studies reporting on symptomatic VTE or bleeding after urological procedures. Additional studies known to experts and studies cited in relevant review articles were added. Teams of two reviewers, independently assessed articles for eligibility, evaluated risk of bias, and abstracted data. We derived best estimates of risk from the median estimates among studies rated at the lowest risk of bias. The primary endpoints were 30-day post-operative risk estimates of symptomatic VTE and bleeding requiring reoperation, stratified by procedure and patient risk factors.
  
  
  CONCLUSIONS
  This series of systematic reviews will inform clinicians and patients regarding the trade-off between VTE prevention and bleeding. Our work advances standards in systematic reviews of surgical complications, including assessment of risk of bias, criteria for arriving at best estimates of risk (including modeling of timing of events and dealing with suboptimal data reporting), dealing with subgroups at higher and lower risk of bias, and use of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to rate certainty in estimates of risk. The results will be incorporated in the upcoming European Association Urology Guideline on Thromboprophylaxis.
  
  
  BACKGROUND
  PROSPERO CRD42014010342.
authors.affiliation: Department of Urology, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland. kari.tikkinen@gmail.com.
authors.forename: Kari A O
authors.initials: KA
authors.lastname: Tikkinen
authors.forename: Arnav
authors.initials: A
authors.lastname: Agarwal
authors.forename: Samantha
authors.initials: S
authors.lastname: Craigie
authors.forename: Rufus
authors.initials: R
authors.lastname: Cartwright
authors.forename: Michael K
authors.initials: MK
authors.lastname: Gould
authors.forename: Jari
authors.initials: J
authors.lastname: Haukka
authors.forename: Richard
authors.initials: R
authors.lastname: Naspro
authors.forename: Giacomo
authors.initials: G
authors.lastname: Novara
authors.forename: Per Morten
authors.initials: PM
authors.lastname: Sandset
authors.forename: Reed A
authors.initials: RA
authors.lastname: Siemieniuk
authors.forename: Philippe D
authors.initials: PD
authors.lastname: Violette
authors.forename: Gordon H
authors.initials: GH
authors.lastname: Guyatt
mesh_terms: D006470:Hemorrhage / Q000209:etiology*; D006801:Humans; D064887:Observational Studies as Topic; D011183:Postoperative Complications; D012107:Research Design; D013923:Thromboembolism / Q000209:etiology*; D013520:Urologic Surgical Procedures