Mean of Daily Versus Single Week Recall-Based Pain Quality Assessments in Painful Chemotherapy-induced Peripheral Neuropathy (CIPN) Trials: Implications for Assay Sensitivity

Patients with neuropathic pain present with different pain qualities. Each is usually assessed using single ratings in randomized clinical trials (RCTs). To our knowledge, no studies have investigated whether means of daily pain quality assessments would provide better assay sensitivity (i.e., more sensitive to treatment effects) than single week recall-based assessments. This secondary analysis used data from participants who reported ³4 out of 10 severity for hot/burning pain, sharp/shooting pain, and/or cramping at baseline in a RCT of transcutaneous electrical nerve stimulation for CIPN (N=88). Participants rated the severity of different pain qualities using 0-10 numeric rating scales daily for a week and a single-week recall-based outcome at baseline and endpoint. Effect sizes (differences in mean pain between placebo and active at endpoint) for the mean of the daily assessments and the single week recall assessments were computed using ANCOVAs. The sample sizes that would be required in future clinical trials to detect the observed effect sizes were calculated (alpha=0.5, power=80%). The effect sizes were greater for the mean of daily outcomes than the single week recall outcome in all cases except for sharp/shooting pain. For hot/burning pain and cramping, the projected sample sizes for the mean ratings were 114 and 126 fewer participants per group than with the week recall outcome. For sharp/shooting pain, the week recall outcome had a slightly lower (22 participants) projected sample size requirement than the mean outcome. Daily pain quality assessments may provide improved assay sensitivity than week recall-based assessments. Funded by NIH (R21CA235389; UG1CA189961; K24NS126861).