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A new California Workers’ Compensation Institute study finds that nonsteroidal anti-inflammatories (NSAIDs) now account for more than a third of all drugs dispensed to injured workers in California, triple the proportion noted for opioids.

The study also reveals that although most NSAIDs that are used are inexpensive, and utilization has been flat since the state’s evidence-based prescription drug formulary took effect in 2018, NSAIDs’ share of the total drug spend has soared from 14.2% to 23.5%, largely driven by increased payments for two low-volume, high-priced drugs that are exempt from prospective utilization review (UR) and that lack price controls.

The CWCI analysis of changes in the distribution of California workers’ compensation prescriptions and prescription payments over the past decade uses data on 5.85 million prescriptions dispensed to injured workers, resulting in payments totaling $623 million.

The data show that opioids accounted for 11.6% of the prescriptions filled in the first half of 2020, down from 31.0% in 2011 – a relative decline of 62.6% during the study period.

NSAIDs, often used as non-opioid alternatives to treat pain, surpassed opioids as the number one drug group in 2015, and in both 2019 and the first half of 2020 they accounted for more than a third of all prescriptions dispensed to injured workers, twice the proportion noted a decade earlier.

Ranking behind opioids in terms of utilization are anticonvulsants, dermatologicals, and antidepressants, which round out the top 5 drug groups.

Musculoskeletal drugs (muscle relaxants), which were the third most heavily used workers’ comp drug group until the formulary took effect, saw their share of the prescriptions fall sharply beginning in 2018 as under the formulary they are subject to prospective UR, with the exception of special fill or perioperative uses, where the quantity of the drug that can be dispensed is limited.

Total payments for a drug group reflect several factors besides the volume of prescriptions, including allowable fees under the pharmacy fee schedule, average quantities and dosages, mode of delivery, and the availability of generics.

While opioids still rank second in workers’ comp prescription volume, the study found their share of the prescription payments fell from 30.7% in 2011 to 7.0% in the first half of 2020, so they now rank fourth in terms of total drug spend, behind NSAIDs (23.5%), dermatological drugs (14.1%), and anticonvulsants (13.1%).

CWCI has released its study in a Research Update report, “California Workers’ Compensation Prescription Drug Trends.