November 2013
Cochrane Database Syst Rev. 2013 Jul 22;7:CD003868. [Epub ahead of print]
Wiffen PJ, Wee B, Moore RA
This further update of a Cochrane review, first published in 2003 and updated in 2007, aimed to determine the efficacy and toxicity of oral morphine in relieving cancer pain. It included randomised controlled trials (RCTs) reporting the analgesic effect of oral morphine in cancer pain against comparators or placebo. Ten new studies with 638 participants were included in this update, with a total number of 62 studies, with 4241 participants. Most trials were small (<100 participants) and 17 studies reported how many people had good pain relief. Various trial designs (mostly cross-over) and comparisons were used between studies, including oral modified release vs. immediate release morphine, as well as different doses via different routes of administration and morphine vs. other opioids. Daily morphine doses averaged between 100 mg and 250 mg.
In this update a new metric of ‘no worse than mild pain’ was devised and set equivalent to ≤30/100 mm on a visual analogue pain intensity scale (VAS). Eighteen studies achieved this level of pain relief on average, and no study reported that good levels of pain relief were not attained. When studies which on individual participants were assessed, ‘no worse than mild pain’ was achieved by 96% of participants (362/377), which was reported to be equivalent to treatment success in 63% (400/638). Adverse effects were common with 6% of participants discontinuing treatment because of these. Meta-analysis or devising numbers needed to treat (NNTs) were not possible due to insufficient comparable data.
DOI: 10.1002/14651858.CD003868.pub3
by Jason Boland