Predictors of placebo treatment acceptability: participant demographics, perceived knowledge, and efficacy

There is significant debate among healthcare providers, researchers, and ethicists concerning the ethics and acceptability of using placebo treatments to alleviate clinical pain. Although a contested issue, empirical evidence demonstrates that placebo analgesia effects can be large and clinically meaningful, with well-defined psychological and neurobiological mechanisms. Recent evidence suggests that there may be ethically permissible placebo clinical applications, as studies have demonstrated that patients may be open to placebo interventions under certain contexts. The aim of the present study was to expand upon the current placebo ethics literature by examining potential predictors of placebo acceptability. This investigation represented a secondary data analysis of variables used in a web-based placebo survey. Participants (n = 100) provided visual analogue scale ratings of the following: placebo analgesia perceived knowledge, treatment acceptability, treatment efficacy, and willingness to participate in placebo analgesia randomized controlled trials (RCTs). Placebo acceptability significantly correlated with treatment efficacy and willingness to participate in RCTs. Regression analyses illustrated that placebo effectiveness ratings accounted for nearly 25% of the variance in placebo acceptability (p < .001). None of the demographic variables (e.g., participant age, income, education, race/ethnicity) were significant predictors of placebo acceptability. Perceived knowledge was not a significant predictor of either placebo treatment effectiveness or acceptability (p > .05). Both placebo analgesia acceptability and efficacy significantly predicted willingness to participate in an analgesic placebo RCT. Findings from this secondary analysis of a published placebo survey (Kisaalita, J Pain 2012) suggest that, while perceptions of placebo efficacy may greatly impact impressions of treatment acceptability, lay individuals likely have uninformed understandings of placebo mechanisms. Future studies are needed to determine whether explicit, mechanism-based education about placebo can beneficially influence perceptions of placebo treatment acceptability.