Ketamine infusion may provide short-term pain relief for patients with complex regional pain syndrome (CRPS), according to a meta-analysis published in Current Pain and Headache Reports. However, study authors acknowledge the need for additional studies examining the efficacy of the drug for CRPS-associated pain.
For this analysis, 2 investigators reviewed independently published randomized controlled trials and cohort studies that assessed intravenous infusion of the N-methyl-D-aspartate receptor antagonist ketamine for the treatment of CRPS.
In included studies, the primary outcome was pain relief, evaluated before and after treatment using the visual analog scale.
The pain relief event rate, defined as the percentage of patients achieving ≥30% pain relief was the secondary outcome. Overall, 15 studies with a total of 258 participants with CRPS were included in the final analysis (mean age, 37.34±9.23 years; mean CRPS duration, 39.67±31.61 months; mean duration of ketamine infusion, 8.41 days). Ketamine concentrations varied highly across studies. Ketamine infusion was found to be associated with a decrease in the average pain score at follow-up when compared with baseline (P <.000001). Immediate pain relief event rate was 69% (n=9 studies; 95% CI, 53%-84%) and pain relief event rate at follow-up ranging from 1 to 3 months was 58% (95% CI, 41%-75%).
The investigators note the current analysis contains a significant level of between-study heterogeneity as well as publication bias. In addition, the findings from this study are limited to a period of 3 months posttreatment onset, and this meta-analysis cannot determine conclusively whether the effects observed with the ketamine treatment are the result of placebo effect, as only one study included in the analysis included a placebo group.
”Our study suggested that ketamine infusion can provide clinically effective pain relief in short term for less than 3 months,” concluded the study authors.
Zhao J, Wang Y, Wang D. The effect of ketamine infusion in the treatment of complex regional pain syndrome: a systemic review and meta-analysis. Curr Pain Headache Rep. 2018;22(2):12.