Patient Understanding of Oncology Clinical Trial Endpoints in Direct-to-Consumer Television Advertising

This study examined how people interpret overall survival (OS), overall response rate (ORR), and progression-free survival (PFS) endpoints in the context of direct-to-consumer television ads. Although there is little research on this topic, initial evidence suggests that people can misinterpret these endpoints. We hypothesized that understanding of ORR and PFS would be improved by adding a disclosure ("We currently do not know if [Drug] helps patients live longer") to ORR and PFS claims.

We conducted 2 online studies with US adults examining television ads for fictional prescription drugs indicated to treat lung cancer (N = 385) or multiple myeloma (N = 406). The ads included claims about OS, ORR with and without a disclosure, or PFS with and without a disclosure. In each experiment, we randomized participants to view 1 of 5 versions of a television ad. After viewing the ad twice, participants completed a questionnaire that measured understanding, perceptions, and other outcomes.

In both studies, participants correctly differentiated between OS, ORR, and PFS via open-ended responses; however, participants in the PFS conditions (versus ORR conditions) were more likely to make incorrect inferences about OS. Supporting the hypothesis, adding a disclosure made expectations around living longer and quality-of-life improvements more accurate.

Disclosures could help reduce the extent to which people misinterpret endpoints like ORR and PFS. More research is needed to establish best-practice recommendations for using disclosures to improve patient understanding of drug efficacy without changing their perception of the drug in unintended ways.