Predictors of duloxetine response in patients with neuropathic cancer pain: a secondary analysis of a randomized controlled trial—JORTC-PAL08 (DIRECT) study

Abstract

Purpose: Duloxetine has some effect against cancer neuropathic pain (CNP); however, predictors of duloxetine response are unclear. This study sought to identify predictors of duloxetine response in patients with CNP. Methods: Patients (N = 70) with CNP unresponsive to or intolerant of opioid–pregabalin combination therapy, with a brief pain inventory-short form (BPI-SF) Item 5 score (average pain) ≥ 4, and with a total hospital anxiety and depression scale score < 20, were randomized to a duloxetine or a placebo group. Multiple linear regression analysis was conducted to identify predictors of duloxetine response as a secondary analysis with the change in the average pain score on day 10 from day 0 as the dependent variable, and the following five covariates; baseline (day 0) average pain score, baseline opioid dose, continuation/discontinuation of pregabalin, and items 20 and 21 score of the short-form McGill pain questionnaire 2 (SF-MPQ-2) as independent variables. Results: Of the four domains (continuous pain, intermittent pain, neuropathic pain, and affective descriptors) score of SF-MPQ-2 on day 0, significant differences were observed in the neuropathic pain domain (p = 0.040) in change on the average pain between day 10 and day 0 in the duloxetine group. Multiple linear regression analysis revealed that patients with a high score for SF-MPQ-2 Item 21 (tingling pain) on day 0 had a significantly greater change in average pain between day 10 and day 0 (p = 0.046). Conclusion: Patients with a high score for SF-MPQ-2 Item 21 might benefit more from duloxetine.