This month's issue of JCSM revisits the thorny issue of commercial motor vehicle (CMV) drivers and obstructive sleep apnea (OSA) with two papers. The first, by Meuleners and colleagues,1 reports that heavy vehicle drivers with OSA had a 3-fold increased risk of crash compared with those who did not have the disorder. The second paper, a study of 318 professional drivers in Taiwan,2 reported that untreated sleep disordered breathing (SDB) progressed over a 3-year period, and that high body mass index, high baseline oxygen desaturation index (ODI), and increase in BMI predicted SDB progression. Further, only about 19% of those initially diagnosed with SDB received/accepted treatment. So, sleep apnea is prevalent, gets worse over time, often goes untreated, and is associated with increased risk of crash. What else is new?
There are significant problems with the methodology of the paper by Meuleners et al., including use of a pressure transducer channel only to “diagnose” sleep apnea (weirdly defined as an “AHI of over 17/h”), and self-reported crash-free status in the controls. Further, no analyses of the accidents in the study group were made to establish primary “fault” of the accident. A 2013 American Trucking Association Report3 found that in 71% of accidents between cars and trucks, the car was “at fault.”3 In addition, no review of the commercial driver's compliance with hours of service regulations at the time of the accident was made. Sleep deprivation is also a prevalent risk factor for crash, and elimination of this potential risk would have given additional strength to the conclusions. This study further emphasizes the need for collaboration between researchers with expertise in transportation safety research and sleep medicine in making correlations between SDB and crash.
However, the study has significant strengths. The same methodology for SDB diagnosis was used in cases and controls. A major strength of this study is that that it addresses crash in commercial drivers; while there is abundant data that untreated sleep apnea is associated with increased risk of crash in the general driving population, there is actually little and often conflicting data about crash risk in commercial drivers with OSA.4–6 One of the research challenges in making a SDB crash risk association is that CMV crashes are statistically rare events. Without large sample sizes or long study durations, a few data points can greatly affect outcomes. The Meuleners study, which started with drivers who were known to have crashed and tested them for SDB, is one way to address this research challenge. In the future, data from National Registry of Certified Medical Examiners examinations, conditional certification, and resulting full certification of CMV operators after SDB testing and treatment may provide greater insight into the true crash risk of SDB and potential benefits of treatment.
Another important finding from the study by Meuleners and colleagues was a reduction in crash risk in those drivers who had undergone fatigue management training. This will likely have significant future applicability in the US. FMCSA recently announced a negotiated rulemaking on new entrant driver training requirements.7 Findings from the Meulener study may support inclusion of fatigue management training available through the North American Fatigue Management Program8 for new US commercial drivers.
In view of all this, a review of the current state of regulation/ legislation about commercial drivers with OSA in the US is in order. The good news is that as of May 21, 2014, the National Registry of Certified Medical Examiners (NRCME) under the Federal Motor Carrier Safety Administration (FMCSA) umbrella is in operation.9 Going forward, all commercial drivers whose commercial driver's license (CDL) needs renewal must be examined by a medical professional listed on the NRCME. These medical examiners must have completed training and successfully passed a test on FMCSA's physical qualification standards. In the current medical evaluation for fitness to drive, the driver and examiner together complete a form in which the driver answers questions, including one about “Sleep disorders, pauses in breathing while asleep, daytime sleepiness, loud snoring.”10 Although there are issues around the validity of driver self-report of SDB symptoms,11 providing false or misleading information to a NRCME medical examiner is a Class I felony.12
The bad news is that the FMCSA is now prohibited by law (Public Law 113-45 passed in October of 2013)13 from using guidance alone to address sleep apnea screening for drivers. This law requires that the FMCSA use the formal (and protracted) rulemaking process rather than previously issued recommendations14 to address restriction/regulation of drivers with SDB. For a while, this left drivers and examiners in limbo. However, earlier this year the FMCSA issued a document entitled, “FMCSA Bulletin to Medical Examiners and Training Organizations Regarding Obstructive Sleep Apnea,”15 noting that “FMCSA's physical qualifications standards and advisory criteria do not provide OSA screening, diagnosis or treatment guidelines for medical examiners to use in determining whether an individual should be issued a medical certificate. Medical examiners may exercise their medical judgment and expertise in determining whether a driver exhibits risk factors for having OSA and in determining whether additional information is needed before making a decision whether to issue the driver a medical certificate…” In language and philosophy strikingly similar to that in the previously issued recommendations, the Bulletin notes that the primary safety goal regarding OSA is to identify drivers with moderate to severe OSA (defined as an AHI > 15/h), with the aim of managing their OSA to reduce the risk of drowsy driving. The Bulletin further notes that while symptoms such as loud snoring, witnessed apneas, and sleepiness are important, objective measures such as body mass index (BMI) and neck size should also be considered. Diagnosis by home testing is acceptable, so long as there is a chain of custody, and treatment options (including dental devices) are “best left to the treating healthcare professional and the driver.”
What does this mean for those of us who are sleep clinicians? First, because of the Registry, Certified Medical Examiners now have more baseline knowledge about sleep apnea and crash, and also more latitude in assessing fitness to drive in commercial drivers with sleep apnea than they have had in the past. When a Certified Medical Examiner sends us a patient with known or suspected sleep apnea for evaluation, he/ she wants the sleep specialist's expert medical opinion about whether the driver is safe to drive, and if not, what will be necessary for him to become so. In some cases, particularly if a home study has been done and has been read as negative, the examiner may ask that an in-laboratory study be done.
The current state of affairs leaves many significant unresolved issues. Among these is whether or not treatment is needed for patients with AHI > 5 but < 15. Questions around whether or not asymptomatic patients with AHI < 15 can be certified by NRCME examiners without treatment have not been clarified by FMCSA as of this time. Another issue is for how long a “negative” sleep study is valid? This is especially critical, given the work by Lin and colleagues, which demonstrates that sleep disordered breathing progresses over time.2 Another conundrum relates to adherence: guidance on what constitutes acceptable CPAP compliance/adherence found in earlier recommendations (≥ 4 h on pressure > 70% of nights) is not addressed in the Bulletin. And the issue of just who is qualified to make these difficult calls (about borderline SDB, adherence, applicability of older studies) is rather murky, since the Bulletin advises the Medical Examiner to “…request additional information from the driver and his or her treating healthcare professional about the management of the driver's OSA…” about unresolved issues. This leaves questions as to whether or not Respiratory Care Practitioners, sleep technologists, or Dental Sleep Medicine Specialists can prepare documentation on a driver's “current and effective treatment” status. In short, there are many troublesome unresolved issues. However, while the Bulletin is short on information or recommendations about the chronic care, follow-up and adherence issues of commercial drivers with OSA, it does provide a great deal of latitude for us exercise clinical judgment. And we should.
Dr. Phillips has served on the Medical Advisory Board of the Federal Motor Carrier Safety Administration, and Mr. Stanton is truck driver with sleep apnea and Co-coordinator of Truckers for a Cause, a support group for US truck drivers with sleep apnea.