RCT · 2025
Comparing 3-, 5- and 7-day ketamine infusion schedules for complex regional pain syndrome
- Original title
- Assessment of Three Regimens of Ketamine Infusion in Complex Regional Pain Syndrome: A Randomized Prospective Comparative Study.
- Authors
- Abo Elsafa AM, El Tatawy HI, Alzeftawy AE, et al.
- Journal
- Pain physician, 2025
- Molecules
- Ketamine
- Conditions
- Chronic pain
- Participants
- 75
- Evidence grade
- Moderate
- Source
- Read the original paper
The question
For people with complex regional pain syndrome, does the number of days of low-dose ketamine infusion change how much pain relief they get and how many side effects they have?
What they did
Seventy-five adults over 21 years old with complex regional pain syndrome, a long-lasting pain condition usually affecting a limb, were randomly split into three groups. Everyone received ketamine infusions lasting 6 hours a day at sub-anaesthetic doses of 0.1 to 0.35 mg/kg per hour, up to a maximum of 24 mg per hour. Group A received 3 days of treatment, Group B 5 days and Group C 7 days. Pain was measured with the Brief Pain Inventory-Short Form and a numerical rating scale at one, two and three months.
What they found
At all three follow-up points, pain scores were significantly lower in the 5-day and 7-day groups than in the 3-day group (P < 0.05). There was no significant difference in pain scores between the 5-day and 7-day groups. Side effects followed the opposite pattern: fewest in the 3-day group, more in the 5-day group, and most in the 7-day group, with each difference reaching statistical significance (P < 0.05). The authors concluded that the 5-day schedule gave the best balance of pain control and side effects.
The fine print
The authors themselves note there was no control group, so it is impossible to say how much improvement came from ketamine rather than from time, attention or other care. The study was done at a single centre with only 75 people and three months of follow-up, and the abstract does not report the actual pain scores, the types of side effects or how severe they were. This summary is based on the abstract alone.
What it means
Among people with complex regional pain syndrome given ketamine infusions, longer courses beyond five days did not add pain relief but did add side effects, though without an untreated comparison group the overall benefit of ketamine here cannot be judged.
Evidence grade: Moderate. Randomized trial, but small, single-centre, with no placebo or no-treatment comparison group and only three months of follow-up.
This summary is based on the study’s published abstract.