The California Workers’ Compensation Institute (CWCI) published a new report on independent medical reviews (IMR), which reviewed 1.57 million IMR decision letters issued from 2015 through March 2025 in response to applications submitted to the state after a Utilization Review (UR) physician modified or denied a workers’ comp medical service request.

The IMR process allows injured workers to challenge denied or modified medical treatments. This report delivers insight into how treatment decisions are being challenged, highlighting which services are most frequently disputed. Despite the uptick in filings, nearly 90% of the decisions continue to be upheld, indicating alignment between IMR physicians and original Utilization Review findings.

After declining steadily from 2018 through 2022, IMR volume is rising again. IMR decision letters increased 2.9% in 2023, 8.2% in 2024, and 13% in Q1 2025 compared to the same period last year.

Prescription drug disputes remain the most common IMR issue but have declined to 30.6% of IMRs in Q1 of 2025, down from 33.4% in 2024 and over 50% in 2015.

Opioid-related disputes dropped from 32% of pharmaceutical IMRs in 2018 to 18.6% in early 2025. As drug-related disputes fall, IMRs involving physical therapy, injections, and DME are on the rise.

The report also found that a small group of physicians continue to drive IMR activity, with just 81 doctors accounting for over 42% of disputed requests.