New Study Links Pre-Injury Opioid and Benzodiazepine Use with Risk and Cost of Post-Injury Disability

A study to be published by the Journal of Occupational and Environmental Medicine supports the widely-held — although not thoroughly documented — notion that pre-injury opioid and benzodiazepine use may increase the risk and cost of disability after a work-related injury [see Esi W. Nkyekyer, MD, MPH, et al., “Opioid and Benzodiazepine Use Before Injury Among Workers in Washington State, 2012 – 2015,” Journal of Occupational and Environmental Medicine (JOEM), DOI:10.1097/JOM.0000000000001346]. Characterized by the authors as “the largest published descriptive study to date characterizing pre-injury opioid and benzodiazepine use among workers’ compensation claimants,” the study notes a correlation between such pre-injury drug use and, inter alia, an increase in days off work and associated wage replacement after an occupational injury has occurred. The study also shows a correlation between the combined use of opioids and benzodiazepines before an injury and compensable claims compared to opioid and benzodiazepine use alone.

Paucity of Research Related to Pre-Injury Drug Use

The researchers allowed that despite the potential for an elevated risk of occupational injury with opioid and benzodiazepine use, only a few studies have actually characterized the use of opioids and benzodiazepines prior to occupational injury. Indeed, the researchers posit that the bulk of current occupational injury literature primarily describes the use of opioids and benzodiazepines, and related outcomes, among injured workers after injury.

The Study’s Design

To fill this gap, at least partially, the researchers crafted their study so as to link 2012-2015 claims data from the Washington State Department of Labor and Industries with the state’s Prescription Monitoring Program data. Readers may recall that, within the state of Washington, the State Fund insures some two-thirds of all non-federal workers. The remaining third generally are employed by large, self-insuring employers. The study included all workers 18 through 65 years of age with “traumatic injuries and disorders” (defined by version 1.01 of the Occupational Injury and Illness Classification System (OIICS)). 313,543 workers’ compensation claims met the study’s criteria for inclusion.

The mean age of injured workers was 38.5 years and the majority of cases were male. Non-benzodiazepine agents primarily used as sleep aids — e.g., zolpidem, suvorexant, eszcopicolone, and zaleplon were not included. Prescription dispensation was used as a proxy measure of medication use in the study. The researchers endeavored to account for differences in age, gender, claim status (compensable vs. non-compensable vs. other), prevalence of opioid and benzodiazepine use before injury, and mean daily morphine equivalent dose (MED) and diazepam equivalent dose (DED) doses among claimants with opioid and benzodiazepine use in the 90 days preceding injury.

Pre-injury prevalence of opioid and benzodiazepine use was compared between compensable and non-compensable claims, and between workers with and without post-injury prescriptions, using the Pearson Chi-Square test.

Primary Findings

The researchers offered a number of findings, including the following:

• > Prevalence of pre-injury opioid use was higher than the prevalence of benzodiazepine use
• > Prevalence of compensable claims was higher among cases with pre-injury opioid use compared to cases without such pre-injury use (28.6 percent vs. 19.5 percent)
• > Prevalence of post-injury opioid use was higher among claims with pre-injury opioid use compared to cases without such pre-injury use (67.2 percent vs. 22.8 percent)
• > Prevalence of post-injury benzodiazepine use was higher among claims with pre-injury benzodiazepine use compared to cases without such pre-injury use (66.9 percent vs. 1.9 percent)
• > Cases with pre-injury opioid and benzodiazepine use had a higher prevalence of compensable claims compared to those with no such pre-injury prescriptions
• > Cases with chronic opioid use were more likely to also be on benzodiazepines compared to cases with acute or intermittent opioid use

According to the researchers, the study findings suggest that pre-injury opioid and benzodiazepine use may indeed be risk factors for adverse injury and post-injury outcomes. They allow that additional work is necessary if the workers’ compensation community is to gain a better understanding of how the use of opioids and benzodiazepines influences occupational injury risk and subsequent morbidity.

Study Limitations

The researchers acknowledged that the study had limitations. For example, the data were drawn from an administrative database that typically recorded claims information at the time medical care was sought. That recording process might take place at a time far-removed from the actual injury. The accuracy of the workers’ recall was a variable that could not be discerned. Other limitations included:

• > Potential selection bias, since include injury data did not include injured workers employed by self-insured companies in Washington State or workers who may have been injured but did not file a claim.
• > The fact that prescription dispensation was used as a proxy for actual use of opioids and benzodiazepines. In other words, the data did not provide information about how these medications were taken. The data reflected likely, but not necessarily actual, exposure to opioid and benzodiazepine prescriptions.
• > The fact that only injured workers were included in the study. The study made no direct comparison to uninjured workers. The researchers acknowledge, therefore, that it is not possible to draw conclusions about whether, for example, 90-day pre-injury opioid and benzodiazepine prevalence rates differ between injured versus non-injured workers.
• > Researchers had no access to information about pre-injury health conditions such as depression, anxiety, and pain disorders. Such conditions are generally associated with an increased likelihood of opioid and benzodiazepine use as well as delays in return to work and receipt of occupational disability benefits.

Commentary

According to a recent report by CBS News, more than one in three Americans used a prescription opioid painkiller in 2015, despite the growing consensus that misuse of such medications is associated with widespread addiction and overdose deaths. Many of these “users” are employed., creating a potentially concomitant increased risk of occupational injury. For example, as documented in this JOEM report, at least half a dozen earlier studies have linked opioid and benzodiazepine use with an increased risk of motor vehicle accidents among drivers. Operating heavy — and not so heavy — equipment, working at heights, and driving a vehicle for hire can be relatively dangerous, per se. Performing such work with opioids or benzodiazepines in the blood stream in many instances is a recipe for disaster.

This JOEM study is iterative; it isn’t earth-shaking. Yet, as they say, Rome wasn’t built in a day. Similarly, a full mosaic of understanding regarding the complex relationship between opioid and benzodiazepine use (and misuse), on the one hand, and occupational injuries and conditions, on the other, continues to be a slow, and somewhat tedious, assembly process. This study provides additional evidence to support current practice guidelines recommending against the use of opioids or benzodiazepines, particularly among workers performing safety-sensitive jobs.

The typical state Workers’ Compensation Act requires the employer (and/or insurer) to provide medical care and treatment, including prescription medications, that are “reasonable and necessary” to treat the injured employee’s injury or condition [see Larson’s Workers’ Compensation Law, § 94.03]. Evidence is mounting, thanks to research such as this JOEM study, that prescribing opioids on a long-term basis, and the concomitant prescribing of opioids and benzodiazepines may no longer be “reasonable” for many injured employees, considering the host of problems associated with such practices.

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