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The number of independent medical reviews (IMRs) used to resolve California workers’ comp medical disputes hit a record low in the first half of 2021, as statewide unemployment remained stubbornly high, non-COVID job injury claims stayed below pre-pandemic levels, millions of Californians continued to work from home, and efforts to reduce prescription drug disputes appear to be paying off, according to a new analysis by the California Workers’ Compensation Institute (CWCI).

California law requires every workers’ comp claims administrator to have a Utilization Review (UR) program to assure that the care provided to injured workers meets the evidence-based treatment guidelines adopted by the state.

Most treatment requests are approved by UR, but in 2012 state lawmakers adopted IMR to allow injured workers to get an independent medical opinion on requests that UR physicians deny or modify. IMR took effect for all claims in July 2013.

CWCI began monitoring IMR activity in 2014. In its latest review, CWCI found that 68,044 IMR decision letters were issued in the first half of 2021 in response to applications submitted to the state, down 3.3% from 70,368 letters issued in the first half of 2020, while the latest full-year tally shows 136,738 letters were issued in 2020, down 16.6% from 163,899 letters in 2019 and down 26% from the record 184,735 letters in 2018.

A review of IMR outcomes found that after reviewing medical records and other information provided to support a disputed treatment request, IMR doctors upheld the UR physician’s modification or denial of the service in 91.2% of the IMRs in the first half of 2021, which was up slightly from the 88.4% uphold rate in 2019.

Disputes over prescription drug requests continued to account for the largest share of the January through June IMR decisions (35.5%), but that percentage has declined from nearly half of all IMR disputes prior to the state’s adoption of opioid and chronic pain treatment guidelines at the end of 2017 and the implementation of the Medical Treatment Utilization Schedule Prescription Drug Formulary in January 2018.

Even with those guidelines and the formulary, opioids still accounted for 25.8% of the 2020 prescription drug IMRs – more than any other category of drug – though that percentage is down from 32.2% in 2018. While pharmaceutical requests have represented a dwindling share of the IMRs, since 2018 requests for physical therapy; injections; and durable medical equipment, prosthetics, orthotics and supplies (DMEPOS) have accounted for an increased share, and together accounted for 35% of all IMRs in the first half of 2021, while all other medical service categories combined accounted for 29.5%.

The overall uphold rate for the first six months of this year was 91.2%, but uphold rates for specific service categories varied, ranging from 84.2% for psych services to 94.4% for injections. The high uphold rates show a high degree of agreement in assessing high-quality care while challenging inappropriate or excessive treatment requests.

As in the past, a small number of physicians accounted for a disproportionate share of the disputed medical service requests that went through IMR this year. The top 10% of physicians identified in the IMR decision letters issued in the 12 months ending in June 2021 accounted for 82.2% of the disputed service requests during that period, while the top 1% (83 providers) accounted for 39.3%.

CWCI has published additional data and analyses on the IMR data through June 2021 in a Bulletin which Institute members and subscribers will find under the Communications tab at