Extrapolation of data has been used for decades to perform quantitative occupational and environmental risk assessments. Extrapolation has been used to develop nearly every one of the hundreds of occupational chemical, physical, and biological exposure standards in the United States and the rest of the world. Such standards have reduced burdens of occupational injuries, illnesses, and diseases. Industrial hygienists, epidemiologists, and toxicologists have developed criteria for these processes including extrapolation such as “(1) a stable positive association with an adverse health outcome; (2) high overall study quality; (3) no substantial confounding; (4) quantitative exposure assessment for individuals; and (5) evidence of a dose–response relationship” to serve as a basis for extrapolation.1 The US Environmental Protection Agency also regularly extrapolates data.2 It is worth noting that, in contrast with the recent American College of Occupational and Environmental Medicine opioid practice guideline,3 most occupational and environmental risk analyses have relied primarily on animal models. Thus, the extrapolation used in the American College of Occupational and Environmental Medicine guideline on safety sensitive work should be substantially less controversial because it uses human population studies rather than animal studies on the effects of opioids.
Dr Swotinsky has suggested that one should only use direct studies of each occupation or task to provide guidance for safe work. His position is that guidance developed from extrapolating 12 large, consistent epidemiological studies of driving activities to nondriving activities that also are safety-sensitive jobs is insufficient; the recommendation not to drive under the influence of opioids should only apply to driving. What he did not state is that the available studies are largely of private drivers. One could therefore take the additional position that there should be no guidance regarding opioid use for any occupation, including those involving work-related driving.
Practically, it is nearly impossible to obtain direct data for most safety-sensitive positions. Many relevant populations are too small and/or too isolated for practical or robust descriptive epidemiological studies. In addition, it is likely unethical to expose control groups in cohort studies to a probable risk of injury or death. The philosophical viewpoint in Dr Swotinsky's letter raises the specter of never having guidance on jobs other than those exactly studied.
Currently, it is common practice among all occupational health and safety professions and regulatory groups to use evidence from other relevant populations when evidence-based research for the target population is scarce, has never been conducted, or is unethical or impossible to obtain. For example, the Federal Motor Carrier Safety Administration Evidence Reports have noted that “because data from studies of [commercial motor vehicle] CMV drivers with [cardiovascular disease] CVD are scarce, we deemed it worthwhile to examine relevant data from studies that investigate crash risk associated with CVD among more general driver populations. While the generalizability of the findings of these studies to CMV drivers may not be clear, such findings do, at the very least, allow the opportunity to draw evidence-based conclusions about the relationship between CVD and motor vehicle crash risk in general.”4(p27) Similar processes are utilized by Federal Aviation Administration for commercial pilots (Robert Johnson, MD, MPH, MBA. Personal Communication, September 26, 2014).5,6 Is Dr Swotinsky suggesting that the Federal Aviation Administration drop its rules on pilot substance use and allow pilots to fly while under the influence of opioids and/or other drugs that impair performance but have not been directly tested in that occupational setting?
Opioids are centrally acting drugs that produce sedation and analgesia, with adverse effects that have been consistently associated with increased risk of motor vehicle crashes.3 The epidemiological and other evidence reviewed uniformly suggests cognitive, reaction, and perceptual impairments that result in motor vehicle crashes. A second systematic review has recently affirmed our findings.7 The evidence demonstrates that both acute and chronic use of opioids impair judgment and pose other safety risks. The burden of proof that the use of potentially impairing substances under such circumstances is not hazardous would be on the makers of these products. Unsurprisingly, none of the medication instructions for opioids have been stripped of warnings to avoid driving and operating machinery.
The cognitive and other skills required for safety-sensitive positions overlap to varying degrees with those required to safely operate a vehicle. These include unimpaired alertness, attention, concentration, reaction time, coordination, memory, multi-tasking abilities, perceptual abilities, thought processing, and judgment. Evidence has documented that opioids produce cognitive impairments, perceptual deficits, and slowed reaction times.8–11 Driving can be viewed as the ideal proxy for determination of levels of impairment for other safety-sensitive duties and tasks. Creating the expectation that empirical studies have to be conducted in every particular safety-sensitive setting and for every position, and that no extrapolation is allowed before we can assume that impairment caused by opioid use may pose a risk, places an unreasonable and perhaps at times impossible burden of proof on adopting steps to ensure occupational safety. Adopting that approach could be considered a dereliction of duty, if argued from the opposing side. For example, a person in a safety-sensitive position might bring a tort action against a health provider or occupational health physician who declared the person using opioids fit for duty, if evidence only suggested that opioids impair driving capacity and increased risk, and an injury or death had occurred. It is reasonably foreseeable that if opioids impair driving, they would impair other safety-sensitive duties. No epidemiological evidence is available to suggest that cognitive impairments are not a problem. Excessively narrowing guidance from safety-sensitive work to a population of private automobile drivers is not rational or likely safe from the standpoint of public health.
The evidence and widely accepted practices suggest that a truck driver, commercial pilot, or nuclear plant machine operator would be similarly likely to be impaired by opioid use. Such workers should not expose their passengers, coworkers, and the general public to impaired decision making and unsafe performance.
Kurt T. Hegmann, MD, MPH FACOEM, FACP
Rocky Mountain Center for Occupational
and Environmental Health, University of
Utah, Salt Lake City, UT
Michael S. Weiss, MD, MPH, FACOEM FAAPMR, FAANEM
Kirk Bowden, PhD, NAADAC
Fernando Branco, MD
Kimberly DuBrueler, PharmD, RPh
Charl Els, MBChB, FCPsych, MMed Psych, ABAM, MROCC
Jeffrey S. Harris, MD, MPH, FACOEM
Steven Mandel, MD
David W. McKinney, MD, MPH
Rafael Miguel, MD
Kathryn L. Mueller, MD, MPH FACOEM
Robert J. Nadig, MD, MPH, FACOEM
Michael I. Schaffer, PhD, MS, DABFT NRCC-TC
Larry Studt, MD
James B. Talmage, MD, FACOEM
Russell L. Travis, MD
Thomas Winters, MD FACOEM, FACPM
Matthew S. Thiese, PhD, MSPH
Ulrike Ott, PhDc, MSPH
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