Vaporized cannabis at low dose led to significant pain reduction in neuropathic pain with an NNT of 3,2 and minimal psychoactive effect.
Summary
n=39 central and peripheral neuropathic pain, vaporized cannabis 1,29%/3,53% THC vs. placebo; NNT=3,2 (placebo vs. low-dose) and NNT=2,9 (placebo vs. medium-dose) for 30% pain reduction, no significant difference between active doses (p>0,7). Psychoactive effects minimal and well tolerated, neuropsychological effects reversible within 1-2 hours.
P
PopulationAdults with central and peripheral neuropathic pain under ongoing conventional treatment, n=39
OutcomeSignificant pain reduction under both active doses vs. placebo; NNT for 30% reduction: 3,2 (placebo vs. low), 2,9 (placebo vs. medium); no significant difference between the active doses (p>0,7)
Confidence in the evidence
Very lowLowModerateHigh
Moderate
The third of four GRADE levels, the effect estimate is probably reliable.
We conducted a double-blind, placebo-controlled, crossover study evaluating the analgesic efficacy of vaporized cannabis in subjects, the majority of whom were experiencing neuropathic pain despite traditional treatment. Thirty-nine patients with central and peripheral neuropathic pain underwent a standardized procedure for inhaling medium-dose (3.53%), low-dose (1.29%), or placebo cannabis with the primary outcome being visual analog scale pain intensity. Psychoactive side effects and neuropsychological performance were also evaluated. Mixed-effects regression models demonstrated an analgesic response to vaporized cannabis. There was no significant difference between the 2 active dose groups' results (P > .7). The number needed to treat (NNT) to achieve 30% pain reduction was 3.2 for placebo versus low-dose, 2.9 for placebo versus medium-dose, and 25 for medium- versus low-dose. As these NNTs are comparable to those of traditional neuropathic pain medications, cannabis has analgesic efficacy with the low dose being as effective a pain reliever as the medium dose. Psychoactive effects were minimal and well tolerated, and neuropsychological effects were of limited duration and readily reversible within 1 to 2 hours. Vaporized cannabis, even at low doses, may present an effective option for patients with treatment-resistant neuropathic pain. PERSPECTIVE: The analgesia obtained from a low dose of delta-9-tetrahydrocannabinol (1.29%) in patients, most of whom were experiencing neuropathic pain despite conventional treatments, is a clinically significant outcome. In general, the effect sizes on cognitive testing were consistent with this minimal dose. As a result, one might not anticipate a significant impact on daily functioning.