Hyperbaric O2 Chamb denials: 34.2% overturned by independent reviewers
In 73 California IMR decisions from 2002 to 2025, reviewers overturned the plan 25 times (34.2%). In the last five years: 28.1% of 32. Denials reach IMR only when a member appeals all the way; read the caveats below before generalising.
By diagnosis
| Diagnosis category | Decisions | Overturned | Last 5 years |
|---|---|---|---|
| Ears/Nose/Throat | 16 | 31.3% | 50.0% of 4 |
| Skin Disorders | 14 | 42.9% | 30.0% of 10 |
| Cancer | 8 | 62.5% | 0.0% of 2 |
| Post Surgical Comp | 6 | 0.0% | 0.0% of 5 |
| CNS/ Neuromusc Dis | 6 | 16.7% | 0.0% of 1 |
| Endocrine/Metabolic | 5 | 60.0% | 66.7% of 3 |
| Orth/Musculoskeletal | 5 | 20.0% | 0.0% of 2 |
By year (last five)
| Year | Decisions | Overturned |
|---|---|---|
| 2021 | 3 | 33.3% |
| 2022 | 17 | 11.8% |
| 2023 | 6 | 66.7% |
| 2024 | 4 | 25.0% |
| 2025 | 2 | 50.0% |
What the findings mention
| What the findings mention | Decisions | Overturned | All decisions here |
|---|---|---|---|
| Published evidence citedThe findings refer to peer-reviewed or published evidence. | 42 | 31.0% | 34.2% |
| Prior therapies failedThe findings mention treatments that were tried without adequate response. | 8 | 25.0% | 34.2% |
| Records did not supportThe findings say the documentation did not show what was needed (usually an upheld denial). | 7 | 14.3% | 34.2% |
| Experimental or investigationalThe findings discuss whether the treatment is experimental. | 6 | 33.3% | 34.2% |
| Guidelines or criteria citedThe findings cite guidelines, criteria or a standard of care. | 3 | 66.7% | 34.2% |
Keyword matches on the reviewer’s findings, not causes. A tag that appears mostly in overturned decisions is worth documenting in an appeal; it is not a guarantee.
From recent overturned decisions
“Nature of Statutory Criteria/Case Summary: The patient requested reimbursement for hyperbaric treatments provided on a daily basis, including weekends. In this case, the patient underwent bilateral modified mastectomies with advancement flaps and free nipple grafting. The provider postoperatively diagnosed threatened and compromised surgical flaps with ischemic changes threatening the newly grafted tissue. Thus, hyperbaric treatments provided on a daily basis, …”
“Nature of Statutory Criteria/Case Summary: The patient has requested authorization and coverage for hyperbaric oxygen therapy (HBOT). The records indicate that the patient developed hip pain after receiving prednisone for a sinus infection. Magnetic resonance imaging (MRI) of the patient’s hip and knee joints demonstrated significant avascular necrosis of the hips and knee joints bilaterally. The patient reported that they …”
“The physician reviewer found that Nature of Statutory Criteria/Case Summary: The patient has requested reimbursement for hyperbaric oxygen therapy. In this case, the patient underwent significant transgender surgery. Photographs submitted on behalf of the patient showed evidence of a hypoxic surgical site indicative of a threatened flap/graft. Researchers report, “The expedient initiation of hyperbaric oxygen therapy as soon as flap …”
- California only: these are decisions by independent reviewers under California's IMR program (plans regulated by the Department of Managed Health Care). Other states and self-funded employer plans use different reviewers and rules.
- Selection: only denials that a member took all the way to IMR appear. Most denials are never appealed, and the ones that reach an external reviewer are not a random sample.
- Overturned means the reviewer disagreed with the plan; it does not mean the treatment worked or that a similar request will be approved.
- Argument tags are keyword matches on the reviewer's findings. They describe what the findings mention, not why the case was decided.
- Categories are DMHC's own labels (treatment sub-category and diagnosis category); 'Other' is a catch-all and is excluded from rankings.
Source: California Department of Managed Health Care, Independent Medical Review (IMR) Determinations, Trend (CHHS Open Data). Public California government data; Apellica's aggregates and tags are CC BY 4.0.
Questions
How often were Hyperbaric O2 Chamb denials overturned?
In 73 California IMR decisions from 2002 to 2025, reviewers overturned the plan 25 times (34.2%). In the last five years: 28.1% of 32.
What did the reviewers' findings mention in overturned cases?
The table on this page counts keyword matches in the findings: prior therapies tried, contraindications, guidelines cited, published evidence, whether the records supported the request. They describe what the findings say, not why the case was decided.
Does a California IMR result apply to my plan?
Only California plans regulated by the Department of Managed Health Care go to IMR. Other states and self-funded employer plans use different reviewers, but the reasoning is the same kind: criteria, documentation and alternatives. Use the findings as a guide to what to document.
Related: California appeal rights · California external-review reversal rate · The levers library · CSV
Independent reviewers reverse plans when the record answers the criteria. Upload the denial letter; a senior reviewer reads it within 24 hours and tells you in writing whether it can be appealed and how. $0 upfront, 10% of what is recovered, nothing if we do not recover. Not a law firm.