The HyperbaricLink Evidence Index

The HyperbaricLink Evidence Index provides a handy reference to the state of clinical evidence on hyperbaric oxygen therapy (HBOT) for many diseases and conditions. The more you know about the clinical evidence, the better you can participate in your healthcare, work with your physician, and help advance evidence-based hyperbaric medical research.


Key Points

  • For some off-label indications the published research supports further study and investigational use of hyperbaric oxygen therapy. For others the clinical evidence is weak (Scant) or totally lacking (None).
  • The Evidence Index can help you be a more informed patient, but it can’t take the place of proper medical consultation. Talk to your doctor before you begin hyperbaric oxygen therapy, and use the information you find here to ask more informed questions.

Evidence Index Categories

HyperbaricLink Evidence Index scoring is based solely on our reading and interpretation of the medical literature. HyperbaricLink distinguishes six categories of clinical evidence:

Approved — HBOT indicated and widely reimbursed. Only FDA-cleared and UHMS-approved clinical indications earn this rating. Learn more about FDA clearance and UHMS approval. There is a scientific consensus for the benefit of HBOT in cases that meet the diagnositic criteria for these medical conditions.

Compelling — Strong body of evidence supporting evidence-based practice. Few off-label indications for hyperbaric oxygen therapy merit such interest and encouragement.

Promising — Repeatedly favorable results urging further study. Hyperbaric oxygen therapy has demonstrated real promise for just a few off-label diseases and conditions.

Scant — Early or mixed results with lingering questions. There is scant evidence for the majority of off-label indications for hyperbaric oxygen therapy.

None — Unfavorable results or no published evidence. HyperbaricLink only publishes pages on these diseases and conditions to highlight the lack of favorable evidence.

Disproved — Strong evidence against using hyperbaric oxygen therapy. Null findings in the hyperbaric medical literature have not yet eliminated any diseases or conditions from further clinical investigation, although a number in the “None” category are not being actively researched.

Scoring Clinical Evidence

We look at a broad range of medical literature in scoring our Evidence Index, but we don’t give every paper equal weight.

  • Some studies are better designed and conducted than others.
  • Some clinical investigators and healthcare institutions are more influential than others.
  • Some medical journals are more highly regarded than others.

The most reliable clinical findings spring from large, prospective, randomized controlled trials (RCTs) published in major peer-reviewed journals. The US Food and Drug Administration (FDA) and Undersea and Hyperbaric Medical Society (UHMS) require RCT evidence for the approval of new clinical indications for hyperbaric oxygen therapy.

The RCT is the gold standard, but not the only standard, for evidence-based medicine (EBM). Randomized controlled trials are expensive to conduct and take years to complete. In the absence of gold standard RCT evidence, published findings from well-designed animal research or smaller human clinical trials may persuade some responsible physicians to adopt new clinical practices.

Strong evidence grows stronger as other scientists replicate, refine, and cite the original findings in new published studies. Weak evidence grows weaker as peers expose weaknesses in study design, data analysis, and professional biases or conflicts of interest.

Of course the state of scientific evidence may change instantly, with the publication of a single paper. So our Evidence Index rating may change the moment we find a new study that meets our criteria. We keep especially alert for findings that refute previous studies and for papers retracted by their authors or journals.

As a rule HyperbaricLink only recognizes papers listed in and clinical trials posted on

You can review the medical literature we consulted by following the links to the Sources on our individual diseases and conditions pages. The links we provide in Clinical Resources will also take you to a wealth of relevant information.

Page Data
Updated: 25 Aug 2015 02:13 PM
Created: 14 Aug 2011 12:00 AM
By: About the authors »