Intravenous Subdissociative-Dose Ketamine Versus Morphine for Analgesia in the Emergency Department: A Randomized Controlled Trial
Journal Club Summary
Methodology Score: 3.5/5
Usefulness Score: 2/5
Motov S, Rockoff B, Cohen V, et al.
Ann Emerg Med. 2015 Mar 26. pii: S0196-0644(15)00191-2.
This prospective, RCT found sub-dissociative ketamine (0.3mg/kg) and morphine (0.1mg/kg) were similarly effective at reducing moderate to severe pain using a visual analogue pain scale at 30 minutes (mean difference 0.2; 95% confidence interval 1.19 to 1.46; P=0.97), but with increased minor side effects in the ketamine group. JC attendees discussed the limitations of using a continuous variable as a primary outcome, likely making this an underpowered study. Additionally, JC attendees thought the significantly increased side effects and short duration of ketamine would limit implementation into clinical practice.
By: Dr. Nathan Hecht
(Presented May 2015)
Sample Size in Clinical Trials
All intervention studies should indicate how the sample size was estimated including the desired alpha error (usually 0.05), power (usually 80-90%), and expected outcome rate in the control group. Most important is a statement of the minimal clinically important difference (MCID) that would have to be shown by the study intervention for clinicians to accept the new treatment as better. In an effort to keep sample size low, investigators sometimes estimate an MCID much larger than is reasonable.
By: Dr. Ian Stiell