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WCRI Study Reveals Causal Connection Between Long-Term Opioid Prescribing and Duration of TTD Benefit Periods

March 23, 2018 (6 min read)

A recent study published by Workers’ Compensation Research Institute (WCRI) argues that there is indeed a causal relationship between the practice of providing extensive opioid prescriptions to an injured worker and the duration of that workers’ temporary disability benefits [see Bogdan Savych, et al., “The Impact of Opioid Prescriptions on Duration of Temporary Disability,” ISBN 978-1-61471-675-4, Workers’ Compensation Research Institute, WC-18-18, March 2018]. The researchers stressed that they had used a research design intended to estimate the causal effect of opioid prescriptions, whereas earlier studies of opioids and return to work had estimated associations that could reflect a combination of causal effects and unobserved injury severity or other sources of variation in return to work that influence both opioid prescriptions and the duration of disability. The study also finds that local prescribing patterns play a strong role in determining whether injured workers receive opioid prescriptions. The combination of these study findings has broad implications for the workers’ compensation world.

The Study

Researchers utilized the WCRI Detailed Benchmark/Evaluation (DBE) database, which tracks payment information on a multitude of workers’ compensation claims from both national and regional insurers, state funds, and self-insured employers across 28 states (Alabama, Arizona, Arkansas, California, Connecticut, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nevada, New Jersey, New York, North Carolina, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, and Wisconsin), for injuries between 2008 and 2013, where workers had more than seven days of lost work time. WCRI estimates that this mix of states and claims represents more than 80 percent of national benefits paid.

Study Restricted to Low Back Injuries

These data were used to extract information about worker, employer, and injury characteristics, as well as opioid prescription patterns and duration of temporary disability benefits. The researchers’ sample was restricted to workers with low back injuries, in which a low back condition was a primary diagnosis code on at least two eligible office visits within the first year of an injury. They stressed that an “office visit criterion” was used in order to assure that the sample included workers who were diagnosed with low back injuries prior to receiving extensive treatment for such injuries. This avoided the sort of “diagnosis bias” that can result from providers selecting specific diagnosis codes that justify their medical treatment.

In order to increase the likelihood that the study’s cases were predominantly low back claims, and not injury claims involving multiple body parts or injuries where low back pain subsequently developed, the researchers further limited the sample to cases where more than two-thirds of the office visits included a low back injury diagnosis.

Local Prescribing Patterns

The researchers also employed estimates of local opioid prescribing patterns to generate variation in opioid prescriptions for individual workers that was unrelated to injury severity or other behaviors affecting disability duration.

Injury Severity

Crucial to the study was the fact that the researchers developed controls for injury severity specific to the low back conditions studied. Without these controls, they would not have been able to claim they had established a causal connection between long-term opioid prescribing patterns and duration of TTD benefits. They developed a separate scoring system for claims that utilized surgical intervention and claims that did not.

Other Controls

The researchers also attempted to account for other characteristics of workers or employers that could affect the TTD benefit duration. For example, since older workers are less likely to return to work, and workers in some industries might have unique return-to-work problems, the researchers included worker controls for age, gender, marital status, tenure at the time of injury, and pre-injury wages. Since return-to-work was also at least somewhat dependent upon characteristics of the local labor market, the researchers controlled for the county unemployment rate and residence in a rural zip code.

Findings: Long-Term Opioid Prescribing May Triple the TTD Benefit Duration

As noted above, the researchers found that prolonged prescribing of opioids leads to longer duration of TTD benefits among workers with low back injury workers’ compensation claims. Specifically, they posit that workers with longer-term opioid prescriptions had triple the duration of TTD benefits than workers with no opioid prescriptions. The researchers also found little evidence of longer duration of TTD benefits when a small number of opioid prescriptions, over a short period of time, was prescribed for the injured worker.

Local Prescribing Patterns Important

The researchers stressed that local prescribing patterns also played a strong role in determining whether injured workers received opioid prescriptions. That is to say, workers living in high-prescription areas were more likely to receive opioid prescriptions than similar workers living in low-prescription areas. They offered a specific example—that a 10-percentage point increase in the local rate of longer-term opioid prescribing was associated with a 2.6-percentage point higher likelihood that an otherwise similar injured worker would receive longer-term opioid prescriptions.

Study Limitations

As with any study, there are limitations inherent within this rather exhaustive WCRI examination. For example, the researchers acknowledge that in order for their findings to be valid, the predictive power of local prescribing patterns has to be high. Moreover, since the study’s sample was limited to a narrow group of predominantly low back injuries, it is not clear that the same findings would be shown if the researchers had examined all claims with more than seven days of lost time. They note that such an extension to all cases would require a different approach to controlling for injury severity. Nor did the study differentiate between the types of opioids prescribed to injured workers.


In spite of mounting evidence that the benefits of long-term opioid therapies are far outweighed by negative impacts (e.g., overdoses, addiction, and other co-morbidities), extensive opioid use among injured workers during the recovery period is common. Indeed, as noted by the WCRI researchers, more than half of injured workers off work for more than seven days with pain medications who did not have surgery nevertheless received an opioid prescription, and many of them received opioids on a longer-term basis.

It seems clear from this study that to the extent a jurisdiction (or employer) is interested in getting an injured worker back to work in as speedy (and medically sustainable) a fashion as possible, stakeholders need to do all within their power to reduce inappropriate long-term opioid prescribing. This study does not, of course, identify what is appropriate and what is not.

Perhaps employers and insurers need to throw down the gauntlet. In the vast majority of jurisdictions, there is some burden to show that medical treatment is “reasonable and necessary.” Extensive opioid prescribing appears, at least from this WCRI study, to be contra-indicated in most cases. While utilization review practices have been severely criticized in a number of states—notably California and Pennsylvania—perhaps heightened UR scrutiny could still be one, of several, tools to test reasonableness of long-term opioid prescribing. Why shouldn’t those who are invested in long-term opioid prescription programs bear the burden of establishing that they are medically worthwhile? Should local prescribing patterns continue to drive the train here?

Omnibus Bill Contains Additional Funding to Counter Opioid Epidemic

The Omnibus Spending Bill that cleared both the Senate and House, and which was signed last Friday afternoon (March 23, 2018) by the President, contains some $3 billion in funding to combat the opioid epidemic. One-third of that spending consists of new funding to states (and Native-American tribes). Let’s hope much of that gets directed to real work in reducing the wide swath of devastation that has been wreaked among many injured workers’ families and lives. 

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