Placebo and nocebo effects in randomized double-blind clinical trials for fatigue in advanced cancer patients

Abstract

9640 Background: We have previously reported significant placebo response in randomized controlled treatment trials for cancer related fatigue (CRF). We conducted a retrospective study to determine the frequency and predictors of response to placebo and nocebo effect in patients with CRF. Methods: We reviewed patients that received placebo in two previous randomized clinical trials conducted by our group and determined the proportion of patients who demonstrated clinical response to fatigue using an increase (ΔFACIT-F score) > 7 from baseline to day 8, and those with nocebo response as those who reported side effects. Baseline patient characteristics and symptoms recorded from the Edmonton Symptom Assessment Scale (ESAS) were analyzed to determine their association with placebo and nocebo effects. Results: A total of 105 advanced cancer patients received placebo. 59 (56%) patients responded to placebo (median Δ FACIT-F score of 22). Worse baseline anxiety and well-being subscale score (univariate) and well-being (multivariate, MR) were significantly associated with placebo response. Common side effects reported were insomnia (79%), anorexia (53%), nausea (38%) and restlessness (34%). MR analysis showed that worse baseline (ESAS) sleep, appetite, nausea, and restless are associated with increased reporting of these side effects ( Table ). Conclusions: Nearly half of advanced cancer patients enrolled in the fatigue trials responded to placebo. Worse physical well-being score was associated with placebo response. Patients experiencing specific symptoms at baseline were more likely to report these as side effects of the medication. These findings should be considered in fatigue clinical trial design. [Table: see text] No significant financial relationships to disclose.