title: Assessing the quality of studies on the diagnostic accuracy of tumor markers.
abstract: OBJECTIVE
  With rapidly increasing numbers of publications, assessments of study quality, reporting quality, and classification of studies according to their level of evidence or developmental stage have become key issues in weighing the relevance of new information reported. Diagnostic marker studies are often criticized for yielding highly discrepant and even controversial results. Much of this discrepancy has been attributed to differences in study quality. So far, numerous tools for measuring study quality have been developed, but few of them have been used for systematic reviews and meta-analysis. This is owing to the fact that most tools are complicated and time consuming, suffer from poor reproducibility, and do not permit quantitative scoring.
  
  
  METHODS
  The International Bladder Cancer Network (IBCN) has adopted this problem and has systematically identified the more commonly used tools developed since 2000.
  
  
  RESULTS
  In this review, those tools addressing study quality (Quality Assessment of Studies of Diagnostic Accuracy and Newcastle-Ottawa Scale), reporting quality (Standards for Reporting of Diagnostic Accuracy), and developmental stage (IBCN phases) of studies on diagnostic markers in bladder cancer are introduced and critically analyzed. Based upon this, the IBCN has launched an initiative to assess and validate existing tools with emphasis on diagnostic bladder cancer studies.
  
  
  CONCLUSIONS
  The development of simple and reproducible tools for quality assessment of diagnostic marker studies permitting quantitative scoring is suggested.
authors.affiliation: Urologische Klinik, Friedrich-Alexander-Universität, Erlangen, Germany.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Goebell
authors.affiliation: Department of Urology, Division of Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Ashish M
authors.initials: AM
authors.lastname: Kamat
authors.affiliation: EORTC Headquarters, Brussels, Belgium.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Sylvester
authors.affiliation: Department of Urology, Division of Surgery, University of British Columbia, Vancouver, Canada.
authors.forename: Peter
authors.initials: P
authors.lastname: Black
authors.affiliation: Department of Urology, Mount Sinai Hospital, New York, NY.
authors.forename: Michael
authors.initials: M
authors.lastname: Droller
authors.affiliation: Scott Department of Urology, Baylor College of Medicine, Houston, TX.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Godoy
authors.affiliation: Ochsner Clinic Foundation, Tom and Gayle Benson Cancer Center, New Orleans, LA.
authors.forename: M'Liss A
authors.initials: MA
authors.lastname: Hudson
authors.affiliation: Urologische Klinik und Poliklinik, Universität des Saarlandes, Saarland, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Junker
authors.affiliation: Department of Surgery (Urology), McGill University, Montreal, Quebec, Canada.
authors.forename: Wassim
authors.initials: W
authors.lastname: Kassouf
authors.affiliation: Section of Experimental Oncology, Leeds Institute of Cancer and Pathology, St James's University Hospital, Leeds, UK.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Knowles
authors.affiliation: Urologische Klinik und Poliklinik, Heinrich-Heine-Universität, Düsseldorf, Germany.
authors.forename: Wolfgang A
authors.initials: WA
authors.lastname: Schulz
authors.affiliation: Department of Urology, University of Berne, Berne, Switzerland.
authors.forename: Roland
authors.initials: R
authors.lastname: Seiler
authors.affiliation: Schön Klinik Nürnberg Fürth, Fürth, Germany; Urologie 24, Nürnberg, Germany. Electronic address: bernd_sd@yahoo.de.
authors.forename: Bernd J
authors.initials: BJ
authors.lastname: Schmitz-Dräger
mesh_terms: D014408:Biomarkers, Tumor / Q000592:standards*; D006801:Humans; D012107:Research Design / Q000592:standards*; D001749:Urinary Bladder Neoplasms / Q000175:diagnosis*
chemical_list: D014408:Biomarkers, Tumor
keywords: Diagnostic accuracy; IBCN classification; NOS; Oxford levels of evidence; QUADAS; STARD; Study quality