A Cochrane review on hyperbaric oxygen therapy (HBOT) for multiple sclerosis included 9 studies with a total of 504 subjects. Two trials produced generally positive results, while the remaining 7 reported generally no evidence of a treatment effect. In these two trials, the mean Expanded Disability Status Scale (EDSS) at 12 months was improved in the HBOT group (group mean reduction in EDSS compared to sham –0.85 of a point, 95%CI –1.28 to –0.42, p= 0.0001). Only the two generally positive trials reported on this outcome at this time (16% of the total participants in this review). Thus, the small number of analyses suggestive of benefit are isolated and difficult to ascribe with biological plausibility.
Comment: The quality of evidence is downgraded by study quality (inadequate or unclear allocation concealment and inadequate intention-to-treat adherence) and imprecise results (limited study size for each comparison).