title: How preliminary data affect people's stated willingness to enter a hypothetical randomized controlled trial.
abstract: OBJECTIVE
  To explore how preliminary trial data affect the general public's stated willingness to enter a randomized clinical trial.
  
  
  METHODS
  We asked 165 prospective jurors to imagine that their physicians wanted them to enroll in a clinical trial. We then presented them with scenarios portraying preliminary trial results--for example, 9 out of 10 patients get better with drug A and 5 out of 10 get better with drug B--and asked after each scenario, whether they would choose to be part of the trial. We designed the scenarios to test how stated willingness to enter the trial would be influenced by: 1) the difference in effectiveness of the 2 treatments based on the patients enrolled thus far; and 2) by the chance that the difference in effectiveness was random (i.e., the P value). The subjects' willingness to enter the trial at various decision points was analyzed using logistic regression.
  
  
  RESULTS
  Fewer subjects were willing to enter the trial as preliminary data indicated either an increasing difference in the effectiveness of the two treatments or an increasing statistical significance of that difference. For example 75% of subjects were willing to enter the research trial before any preliminary data were presented, but this number fell to 49% when subjects were presented with preliminary data showing that 9 out of 10 patients improved with one treatment and 5 out of 10 with the other. Multivariable logistic regression revealed that higher P values (odds ratio = 4.29; P < 0.001; 95% CI: 2.22-8.28) and smaller differences in effectiveness (odds ratio = 0.02; P < 0.001; 95% CI: 0.00-0.07) implicit in preliminary data presented to subjects made subjects less likely to agree to enter clinical trials. After adjustment for other relevant variables, male gender was associated with increased willingness to enter the trial.
  
  
  CONCLUSIONS
  A subjects' willingness to enter the hypothetical trial was influenced by preliminary data. Fewer subjects were willing to enter the trial as the differences in benefit between 2 treatment groups increased. However, the majority of subjects were willing to enter the hypothetical trial even when preliminary evidence strongly favored one treatment over another. Given the importance of informed consent in entering patients in clinical trials, these results should be confirmed in actual trial settings.
authors.affiliation: Veterans Affairs Medical Center, Philadelphia, PA, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Ubel
authors.forename: J F
authors.initials: JF
authors.lastname: Merz
authors.forename: J
authors.initials: J
authors.lastname: Shea
authors.forename: D A
authors.initials: DA
authors.lastname: Asch
mesh_terms: D000328:Adult; D003657:Decision Making; D004992:Ethics, Medical; D005260:Female; D006801:Humans; D007258:Informed Consent; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010358:Patient Participation / Q000523:psychology*; D016032:Randomized Controlled Trials as Topic / Q000379:methods* / Q000523:psychology; D016896:Treatment Outcome