Press Release


Bob Young

For Release:

May 17, 2020

CWCI Study Finds a Sharp Drop in California Workers' Comp Independent Medical Reviews

Oakland, CA – A new California Workers’ Compensation Institute (CWCI) study on the Independent Medical Review (IMR) process used to resolve California workers’ comp medical disputes finds that the number of IMR determination letters, fueled by a sharp decline in prescription drug disputes, fell 11.3% from 2018 to 2019, with data from the first quarter of 2020 showing the decline is continuing.    

 The CWCI study examined data from more than one million IMR decision letters that were issued from 2014 through March 2020 in response to applications submitted to the state after a Utilization Review (UR) physician modified or denied a medical service requested for an injured worker.  As in prior studies, CWCI researchers used the data to measure changes in the volume, timeliness, and regional distribution of IMRs; determine the number, mix, and uphold rates for the medical service requests that were reviewed; examine the distribution and outcomes of pharmaceutical IMRs by drug category; measure the percentage of IMRs associated with high-volume medical providers; calculate the distribution of pharmaceutical vs. non-pharmaceutical IMRs by claim age; and estimate the percentage of IMRs submitted after a UR physician approved a service at a lesser quantity than requested to comply with the evidence-based guidelines that provide the clinical rationale for the medical services provided to injured workers’ in California.

State lawmakers expected IMR volume would decline over time as providers became familiar with the treatment guidelines, but the number of IMR determination letters increased steadily over the first five years of the program -- the only exception being a modest 2.6% decline in 2017.  The 2019 tally, however, shows the IMR letter volume finally did drop sharply, falling to a five-year low of 163,899, down 11.3% from 2018, while the count from the first quarter of this year shows the decline is continuing, as the letter count from the first three months of 2020 fell 4.9 percent below the total from the corresponding period of 2019, dropping to a 5-year low of 38,981. The year-to-year declines in letter volume were noted in all 8 regions of the state, with the biggest reduction in letter count noted in the Bay Area, which had about 6,200 fewer letters in 2019 than in 2018, a decline of more than 14%, though the rural, sparsely populated Northern Counties and Sierras showed the biggest percentage decline (26.3%).  As in prior years, a small number of physicians continued to drive much of the IMR activity in 2019, with the top 1% of requesting physicians (106 doctors) accounting for 41.2% of all disputed service requests determined by IMR in 2019; and the top 10 individual physicians alone accounting for 9.9% of the disputed requests.   

IMR outcomes have shown little variation as IMR physicians in 2019 upheld 88.2% of UR doctors’ modifications or denials of services, compared to 88.6% in 2018, and 88.5% in the first quarter of 2020.  Uphold rates last year ranged from 74.9% for evaluation/management services to 92.7% for acupuncture; physical therapy; and durable medical equipment, prosthetics, and supplies.  The mix of services reviewed by IMR physicians in 2019 showed prescription drug requests continued to top the list, accounting for 41.1% of the IMRs (and 30.9% of those were for opioids), though that was down from 46.4% in 2018 and down from nearly half of all IMRs in 2015, prior to the adoption of new opioid and chronic pain guidelines in late 2017, and the implementation of the workers’ compensation prescription drug formulary in January 2018.   

CWCI has issued its latest IMR analysis in a Research Update Report, “Independent Medical Review Decisions: January 2014 Through March 2020,” which is posted under the Research tab at