What independent reviewers reverse
California publishes every Independent Medical Review decision: the diagnosis, the treatment, the reviewer's finding and whether the plan was overturned. That makes it the only complete public record of what happens when a denial leaves the insurer's hands. 42,710 decisions, tabulated.
The trend matches what New York's external-appeal database shows (38% overturned in 2019 rising to 52.5% in 2025, per the JAMA Internal Medicine analysis of 51,394 cases published in 2026): when a physician outside the plan reads the file, the plan's decision fails more often every year. Two states, two records, one direction.
By what the reviewer was asked
| Decision type | Decisions | Overturned | Rate | Rate since 2021 |
|---|
Treatments reviewers reverse most and least
Treatment categories with at least 200 decisions (0 categories). Each links to the full page with the diagnosis breakdown, the arguments that appear in overturned decisions, and attributed excerpts from the reviewers' findings.
| Most often reversed | Decisions | Rate |
|---|
| Least often reversed | Decisions | Rate |
|---|
By diagnosis group and by treatment group
| Diagnosis group (500+) | Decisions | Rate |
|---|
| Treatment group (500+) | Decisions | Rate |
|---|
Age and urgency
| Patient age | Decisions | Rate |
|---|
| Review type | Decisions | Rate |
|---|
Children under 11 win about two-thirds of reviews; patients over 65 win under half. Expedited reviews, decided in days, reverse the plan more often than standard ones.
Method and limits
- 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.
- Categories are the DMHC's own treatment and diagnosis labels. A decision counts as overturned when the plan's denial was reversed in whole or in part. Categories under the thresholds shown are omitted from the tables but present in the CSV.
Reuse this research
Free to cite, quote, chart and republish with attribution (CC BY 4.0). Every figure is reproducible from the downloads below.
Apellica (2026). What independent reviewers reverse: California IMR decisions. https://apellica.com/research/what-independent-reviewers-reverse-2026
Source: California Department of Managed Health Care, Independent Medical Review (IMR) Determinations, Trend (CHHS Open Data). Methodology: apellica.com/appeal-outcomes/california-imr/methodology.
Corrections: editorial@apellica.com · Press: press@apellica.com · Nothing here predicts an individual claim; it describes populations.
General information, not legal or medical advice. Apellica is an appeal-preparation service, not a law firm.