title: What Should Be the Cut Point for Classification Criteria of Studies in Gout? A Conjoint Analysis.
abstract: To determine the acceptable level of positive predictive value (PPV) and negative predictive value (NPV) for classification criteria for gout, given the type of study.
  
  
  
  We conducted an international web-based survey with 91 general practitioners and rheumatologists experienced in gout. Conjoint analysis was used as the framework for designing and analyzing pairs of 2 profiles, each describing a study type, a PPV, and an NPV. There were 5 study types presented: a phase III randomized controlled trial (RCT) of a nonsteroidal antiinflammatory drug versus prednisone for acute gout flares, a phase III RCT of a biologic agent for acute gout flares, a phase II RCT of a novel uricosuric drug of unknown efficacy and limited toxicity data, a case-control, genome-wide association study of gout, and a cohort study examining long-term outcomes of gout. PPV and NPV both had 5 levels ranging from 60-99%.
  
  
  
  The panelists in majority were male (65%) rheumatologists (93%) with an average of 19 years of practice, seeing 5 to 60 gout patients monthly. PPV was most highly weighted in decision making: the relative importance was 59% for PPV, 29% for NPV, and 13% for study type. The preferred PPV was 90% or 80%, with an accompanying NPV of 70% or 80%, dependent on study type.
  
  
  
  Preferred PPVs and NPVs range between 70% and 90% and differ by study type. A single cut point can be a reasonable approach for all study types if a PPV of 90% and NPV of 80% is approximated.
authors.affiliation: Radboud University Medical Centre, Nijmegen, The Netherlands. Jaap.Fransen@Radboudumc.nl.
authors.forename: Jaap
authors.initials: J
authors.lastname: Fransen
authors.affiliation: Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: Wietske
authors.initials: W
authors.lastname: Kievit
authors.affiliation: Boston University Schools of Medicine and of Public Health, Boston, Massachusetts.
authors.forename: Tuhina
authors.initials: T
authors.lastname: Neogi
authors.affiliation: University of Pennsylvania and VA Medical Center, Philadelphia, Pennsylvania.
authors.forename: Ralph
authors.initials: R
authors.lastname: Schumacher
authors.affiliation: Vie Curi Medical Centre Venlo, Venlo, and Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: Tim
authors.initials: T
authors.lastname: Jansen
authors.affiliation: University of Auckland, Auckland, New Zealand.
authors.forename: Nicola
authors.initials: N
authors.lastname: Dalbeth
authors.affiliation: University of Otago, Wellington, New Zealand.
authors.forename: William J
authors.identifier: 0000-0001-6075-8479
authors.initials: WJ
authors.lastname: Taylor
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D000066491:Clinical Decision-Making / Q000379:methods*; D017322:Clinical Trials, Phase II as Topic; D017326:Clinical Trials, Phase III as Topic; D015331:Cohort Studies; D005260:Female; D055106:Genome-Wide Association Study; D006073:Gout / Q000145:classification* / Q000175:diagnosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012015:Reference Standards; D012219:Rheumatology / Q000592:standards*; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires