Sleep Apnea Plays Role in Car Crashes
Excessive daytime sleepiness from obstructive sleep apnea (OSA) contributed to excess car crashes, particularly in untreated men, a study showed.
Among sleep clinic referrals, men who scored high for sleepiness reported about a quarter more motor vehicle accidents and nearly five-fold more near misses than those scoring in the normal range, Kim Ward, BSc, of the University of Western Australia in Crawley, and colleagues found
Sleepiness score also correlated with crashes among women (P=0.02), although without a dose effect, the group reported in the Oct. 15 issue of the Journal of Clinical Sleep Medicine.
Overall, untreated OSA patients had a crash rate three times greater than that of the general population (0.06 versus 0.02 motor vehicle accidents per person-year).
While the link between OSA and accidents came as no surprise, the results suggested increased sleepiness put people at the highest risk regardless of OSA severity, "underlining the importance of advising such patients, and the community generally, against drowsy driving," the researchers wrote.
Prior studies have shown that treating OSA with continuous positive airway pressure (CPAP) reduced the risk of car accidents, they pointed out.
It's not worth the agony of hurting yourself or somebody else because you didn't seek treatment. The treatments work," agreed W. Christopher Winter, MD, in practice at Virginia's Charlottesville Neurology and Sleep Medicine.
A few states have enacted legislation against drowsy driving, although difficult to enforce.
However, there has been a move toward treating sleep apnea much like epilepsy among drivers, Winter told MedPage Today.
That has particularly been true in the commercial trucking industry, which has been targeted with some proposed federal legislation for screening, testing, and treatment of sleep apnea.
The Federal Motor Safety Administration has warned about the risks posed by sleep apnea and is reportedly considering regulations for commercial vehicle drivers with the disorder.
Many states already have medical regulations that call sleep apnea a disqualifying condition for truckers.
An estimated 20% to 50% of commercial drivers have sleep apnea. That high proportion may be in part due to the sedentary nature of long-haul trucking that contributes to obesity as a risk factor for sleep apnea, according to a statement from the American Academy of Sleep Medicine in support of federal legislation.
Winter, a spokesperson for that organization, warned that laws to indiscriminately disqualify anyone with sleep apnea from holding a commercial drivers license will drive people away from getting diagnosed and thus treated.
It's important that individuals at risk for driving have a pathway to get the help they need and return to operating a motor vehicle safely," he said in an interview.
For the noncommercial driver, American Thoracic Society guidelines released in June suggested that physicians should routinely determine the driving risk for patients with sleep apnea and educate patients about that risk.
"Clearly, it is important that OSA is diagnosed and the degree of associated sleepiness assessed to expedite treatment and minimize risk," Ward's group concluded.
Their retrospective case-series included 2,673 patients referred for assessment of suspected sleep disordered breathing at a tertiary hospital-based sleep clinic as part of the West Australian Sleep Health Study cohort.
Self-completed questionnaire responses indicated moderate to severe excessive sleepiness in 17% as marked by an Epworth Sleepiness Score (ESS) of 16 or higher.
Most of the cohort reported having ever had a motor vehicle crash (69%), and among them 11% said it was because they felt sleepy or fell asleep behind the wheel.
Near misses due to sleepiness were reported by 26%; while 32% reported having fallen asleep behind the wheel irrespective of whether it caused a crash.
People with any OSA -- nearly the entire cohort with an Apnea-Hypopnea Index of at least 5 events per hour -- were 3.07 times more likely to report any crash compared with the community-wide rate (95% CI 2.98-3.17).
That risk rose significantly with severity of OSA in men, but was lower with severe OSA among women. Near misses followed the same pattern.
However, both genders showed more risk linked with sleepiness.
Men who fell into the "very sleepy" category with an ESS score of 15 to 24 reported 4.86-fold more near misses (95% CI 3.07-7.14) and 1.27-times more car accidents than those in the normal ESS range (95% CI 1.00-1.61) after adjustment for potential confounders.
The majority of the cohort was male, middle-aged, and obese. Men had higher apnea scores compared with women, averaging 31 apnea-hypopnea events per hour compared with 18 per hours on overnight laboratory-based polysomnography (P<0.001).
Sleepiness was associated with accidents among women overall (P=0.02) but without a significant trend by ESS categories (P=0.40).
"The gender differences found in our study may be confounded by driving exposure, which we did not measure," the researchers noted.
Also, "gender differences may be attributable to a higher degree of self-awareness of symptomology in women who self-regulate risk by avoidance of driving," they suggested.
Ward's group cautioned about the possibility of recall or reporting bias from self-reported data over one's entire driving history, but pointed out that the large sample size and narrow confidence intervals supported the results