Evidence Trace, complete trial record
In plain terms
In plain terms: Hyperbaric Oxygen Therapy shows early signals in human research but the evidence is limited -- small trials, surrogate endpoints, or not yet independently replicated. It is an emerging area, not yet a proven one.
Hyperbaric Oxygen Therapy
C
Limited: small, mixed or unreplicated trials
The endpoint this grade is based on: Objectively measured functional outcome
The evidence as the record states it
Hadanny et al. (Aging Albany NY, 2020; PMID 32589613): RCT: HBOT improved some cognitive measures in healthy older adults. Collet et al. (Lancet, 2001; PMID 11558483) is a pediatric cerebral-palsy RCT of narrower scope. Grade C: one randomized trial in 63 healthy older adults, not repeated by an independent group.
PMID 32589613 PMID 11558483
Evidence by specific use
2.0 ATA or higher, 100% oxygen by mask or hood
Grade C
Hadanny et al. (Aging, 2020; PMID 32589613): 63 healthy adults over 64, 60 sessions at 2.0 ATA with 100 percent oxygen or no treatment for 3 months; global cognitive function improved, most in attention and processing speed. One trial, with no sham arm and not repeated by an independent group: C.
PMID 32589613
1.3 to 1.5 ATA, concentrator air
Grade D
PMID 11558483
Why Grade C and not Grade B
Grade C reflects early or limited human evidence -- small trials, surrogate endpoints, or preliminary findings not yet independently replicated. The evidence points in a promising direction but does not yet meet the standard for Grade B. A single well-powered, independently replicated trial with a meaningful endpoint would move this to Grade B or higher.
What this grade covers and what it does not
Grade C at 2.0 ATA or higher with 100 percent oxygen, on cognitive measures in healthy older adults: one trial of 63 people (Hadanny et al., 2020; PMID 32589613), not repeated by an independent group. At 1.3 to 1.5 ATA on concentrator air the use is graded D: that was the sham condition, and it showed no benefit; a pediatric cerebral palsy trial is narrower in scope (Collet et al., 2001; PMID 11558483). WHAT THIS GRADE DOES NOT COVER: chambers by shell type, since a rigid shell does not settle pressure or gas; and clinical outcomes such as dementia, which no cited trial measured.
What would move this grade
A well-powered randomized trial with an objective, clinically meaningful primary endpoint and at least one independent replication would support Grade B or higher.
How to track whether this is working
The primary clinical endpoint specific to the indication: wound size for non-healing wounds, neurological function scales for post-stroke or TBI, cognitive testing for longevity applications. Session count, pressure (ATA), oxygen concentration, and session duration at every treatment. The most-studied longevity protocol used 60 sessions at 2.0 ATA over 90 days.