• Jon H Raphael, Rui V Duarte, Jane L Southall, Peter Nightingale, and George D Kitas.
• Faculty of Health, Birmingham City University, Birmingham, UK.
• BMJ Open. 2013 Jan 1;3(7).

ObjectiveThis study aimed to investigate the efficacy of intrathecal morphine in the long term by hypothesising that a reduction of the intrathecal opioid dose following long-term administration would increase the level of pain intensity.DesignRandomised, double-blind, controlled, parallel group trial.SettingDepartment of Pain Management, Russells Hall Hospital, Dudley, UK.Participants24 patients with non-cancer pain implanted with morphine reservoirs were assessed for eligibility.InterventionsParticipants were randomly allocated to one of two parallel groups in which one of the groups had no change in morphine dose and the other group had a small reduction (20%) in dosage every week during a 10-week follow-up.OutcomePrimary outcomes were visual analogue scale (VAS) pain score change and withdrawal from the study due to lack of efficacy.Results9 of the patients assessed for eligibility declined to participate in the study. 15 patients were randomised to control (n=5) or intervention (n=10) and included in an intention-to-treat analysis. Owing to worsening of pain, seven patients withdrew from the study prematurely. None knew prior to withdrawal which arm of the study they were in, but all turned out to be in the dose-reduction arm. The calculation of dropout rates between groups indicated a significant statistical difference (p=0.026) and recruitment was ceased. The VAS change between baseline and the last observation was smaller in the control group (median, Mdn=11) than in the intervention group (Mdn=30.5), although not statistically significant, Z=-1.839, p=0.070; r=-0.47. Within groups, VAS was significantly lower at baseline (Mdn=49.5) than at the last observation (Mdn=77.5) for the reduction group, Z=-2.805, p=0.002; r=-0.627 but not for the control group (p=0.188).ConclusionsThis double-blind randomised controlled trial of chronic intrathecal morphine administration suggests the effectiveness of this therapy for the management of chronic non-cancer pain. However, owing to the small number of patients completing the study (n=8), further studies are warranted.Trial RegistrationInternational Standard Randomised Controlled Trials Centre (ISRCTN 33733462).

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