RANDOMIZED TRIAL OF ORAL MORPHINE FOR CHRONIC NONCANCER PAIN

Background The use of opioid analgesics for chronic noncancer pain is controversial. Some surveys report good pain relief and improvement in performance while others suggest a poor outcome with a propensity to psychological dependence or addiction. Methods We undertook a randomis ed double-blind crossover study to test the hypothesis that oral morph ine relieves pain and improves the quality of life in patients with ch ronic regional pain of soft tissue or musculoskeletal origin who have not responded to codeine, antiinflammatory agents, and antidepressants . Morphine was administered as a sustained-release preparation in dose s up to 60 mg twice daily and compared with benztropine (active placeb o) in doses up to 1 mg twice daily over three-week titration, six-week evaluation, and two-week washout phases. Pain intensity, pain relief, and drug liking were rated weekly and psychological features, functio nal status, and cognition were assessed at baseline and at the end of each evaluation phase. Findings After dose titration in the 46 patient s who completed the study, the mean daily doses of drugs were morphine 83.5 mg and benztropine 1 7 mg, On visual analogue scales, the morphi ne group showed a reduction in pain intensity relative to placebo in p eriod I (p=0 01) and this group also fared better in a crossover analy sis of the sum of pain intensity differences from baseline (p=0.02). N o other significant differences were detected. Interpretation In patie nts with treatment-resistant chronic regional pain of soft-tissue or m usculoskeletal origin, nine weeks of oral morphine in doses up to 120 mg daily may confer analgesic benefit with a low risk of addiction but is unlikely to yield psychological or functional improvement.