Evaluation of Selective Outcome Reporting Bias in Efficacy Endpoints in Print and Television Advertisements for Oncology Drugs

Abstract

Selective outcome reporting bias in oncology drug advertisements may encourage misconceptions about a drug's efficacy profile. We sought to determine the rates of selective outcome reporting in published cancer clinical trials and in television and print advertisements for anticancer medications. We also quantified the number of advertisements that did not include or cite any studies with mature overall survival (OS) data (i.e., data with all required patient events for final analysis). We conducted a cross-sectional investigation of advertisements uploaded to the AdPharm Database (repository of pharmaceutical advertisements); the clinical trials supporting the ads; and the trial registrations associated with the trials. Data were extracted by two investigators who were blinded to each other's data. The first co-primary objective was to investigate selective outcome reporting between trial registrations and published trials. The second co-primary objective was to investigate selective outcome reporting between the same published trials and drug advertisements. We included 74 advertisements and 48 clinical trials. Print ads were the most common (n = 66), and most print advertisements were targeted to health care providers (n = 55, 83.3%). Overall, 41/48 (85.4%) trials were registered prior to study enrollment, and 41/48 (85.4%) did not deviate from the registered primary endpoints. Across all advertisements (n = 74), statistically significant endpoints were more often reported (unadjusted risk ratio [uRR] 1.26; 95% confidence interval [CI] (1.14-1.40)) and 22/55 (40.0%) advertisements cited trials with immature overall survival data (i.e., data without the required number of events for final analysis). In our sample, statistically significant endpoints were more commonly reported than nonsignificant endpoints. Immature endpoints (those analyzed before the required number of accrued patient events) were often reported. By reporting only significant endpoints and those that are immature, advertisers may encourage misconceptions about a drug's efficacy profile.