A retrospective study of duloxetine for phantom limb pain post lower-limb amputation

BackgroundPhantom limb pain (PLP) refers to the painful sensory perception of a missing limb after amputation, which can have physical and psychological impacts.AimTo determine the effectiveness of duloxetine for pain management in PLP by the reduction of opioid doses and other neuropathic analgesics when introduced into multimodal pain management strategies in the subacute rehabilitation setting.MethodThis was a retrospective observational case-matched cohort study of patients who were admitted to a geriatric and rehabilitation unit at a tertiary Australian hospital from January 2005-December 2017 with PLP after lower-limb amputation. Patients were included if they had a new amputation and experienced PLP. The primary outcome was a difference in oxycodone dose equivalents at discharge between the two cohorts. Univariable analysis was used to compare groups. Ethical approval was granted by the Metro South Low Negligible Risk Ethics Committee (Reference no: LNR/2018/QMS/47370) and the study conforms with the National statement on ethical conduct in human research.ResultsThirty patients from the duloxetine treatment cohort and 57 patients from the non-duloxetine cohort were identified. Participants were predominantly male (81%) and had a median age of 63 years (interquartile range = 10.7). Both populations showed a similar rate of opioid dose reduction comparing doses at admission with those at discharge. There were no significant differences in absolute oxycodone equivalent doses at the two observed check points: admission and discharge.ConclusionThis study demonstrated that opioid consumption in post-surgical lower-limb amputees reporting PLP was not significantly different between populations that used and did not use duloxetine. Future research should evaluate the efficacy of duloxetine in PLP pain management using a multisite prospective study design.