Current evidence suggests ketamine may be an effective therapy for the management of chronic noncancer pain, according to a meta-analysis published in the European Journal of Pain.
In this study, researchers evaluated 6 clinical trials comparing ketamine (n=99) with placebo (n=96) in patients with chronic pain. Primary endpoint for this analysis was pain relief at 4 weeks after treatment initiation; secondary outcomes included pain relief at 1, 2, 8, and 12 weeks and incidence of psychedelic manifestations.
Based on very low GRADE evidence in 4 studies, patients receiving ketamine did not experience a significant decrease in pain intensity at 4 weeks (mean difference [MD] on a 0 to 10 scale, −1.12; 95% CI, −2.33 to 0.09; P <.001). Included studies indicated an association between ketamine and reduced pain intensity at 1 week (MD, −1.42; 95% CI, −2.40 to −0.44; P <.001), 2 weeks (MD, −1.66; 95% CI, −2.96 to −0.36; P <.001), 8 weeks (MD, −1.11; 95% CI, −1.74 to −0.48; P =.87), and 12 weeks (MD, −0.82; 95% CI, −1.42 to −0.23; P =.75). In 4 studies, psychedelic manifestations had higher incidence in participants treated with ketamine vs placebo (risk ratio, 5.35 [ 2.64-10.81]).
Despite these findings, a trial sequential analysis demonstrated a lack of power with this study. The small number of trials, as well as the small patient groups within each study, represent additional limitations associated with this analysis.
In addition to validating the favorable effect of ketamine on pain outcomes, researchers suggest future studies should be designed to determine optimal target populations for treatment as well as “the timing and duration of ketamine administration during chronic pain management, optimal dosage and regimes, and the timing of side effects associated with the administration of ketamine.”
Michelet D, Brasher C, Horlin AL, et al. Ketamine for chronic non-cancer pain: A meta-analysis and trial sequential analysis of randomized controlled trials [published online November 26, 2017]. Eur J Pain. doi: 10.1002/ejp.1153