Crossover trials

Researchers investigated the efficacy and side effects of the synthetic cannabinoid nabilone in comparison with those of the weak opioid dihydrocodeine for treating chronic neuropathic pain. A randomised, double blind, crossover trial was used. In total 96 participants with chronic neuropathic pain aged 23-84 years were recruited. Treatments were delivered in an escalating manner so that by the end of a six week treatment period the participants were receiving a maximum daily dose of 240 mg dihydrocodeine or 2 mg nabilone. The trial lasted for 14 weeks, comprising two treatment periods each of six weeks’ duration, separated by a two week washout period.1

The main outcome measure was pain as measured on a visual analogue scale over the final two weeks of …