Potential unblinding in a crossover trial of cannabis cigarettes for relief of neuropathic pain
Mireles, J.R. (2008) Potential unblinding in a crossover trial of cannabis cigarettes for relief of neuropathic pain. Epidemiologic Focus, 1. e4. ISSN 1944-3307
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Wilsey et al. recently explored the effect of cannabis cigarettes on neuropathic pain. However, the psychoactive side-effects measured as secondary outcomes in this study could have led to the unblinding of study participants. First, all of the participants were previous marijuana smokers. Thus, the participants would likely recognize the effects of marijuana and may be motivated to report positive effects on pain. Second, this study failed to show an effect on antinociception, whereas a separate study indicated a significant dose-dependent antinociception effect. Therefore, unblinding could have contributed to higher participant-reported visual analog scale scores after cannabis administration and resulted in effect estimates that incurred a positive bias away from the null.
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