Key Questions

Are individuals with OSA at an increased risk for a motor vehicle crash when compared to comparable individuals who do not have the disorder?
There is strong evidence that as a group, drivers with OSA are at an increased risk for a motor vehicle crash when compared with comparable drivers who do not have the disorder.



What disease-related factors are associated with an increased motor vehicle crash risk among individuals with OSA?
Four factors have been shown to be associated with crash risk among the general driver population. These factors are the presence and degree of daytime sleepiness as measured using Epworth Sleepiness Scale, severity of disordered respiration during sleep (as measured by the AHI or the RDI), blood SaO2 levels, and BMI.

Diabetes, Hypertension, Obesity BMI>30, Upper Airway Abnormalities and Large Neck sizes >17inches for men and 16 inches for women are all associated with an increased risk for OSA.



Are individuals with OSA unaware of the presence of the factors that appear to be associated with an increased motor vehicle crash risk?
Individuals are likely to be able to tell if they were obese by their BMI measurement, however it is unlikely they would be able to judge the severity of their OSA. Sleep testing would provide answers to the severity of OSA, measured by AHI or RDI but may not be of benefit in determining the extent to which they are affected by daytime sleepiness.

Signs that a drive is fatigued:
• Constant yawning
• Blurred vision
• Sore or heavy eyes
• Poor concentration
• Variations in driving speed
• Letting your vehicle drifts out of lanes
• Difficulty



Are there screening/diagnostic tests available that will enable examiners to identify those individuals with OSA who are at an increased risk for a motor vehicle crash?
It is important to identify and treat drivers with OSA. There is currently a shortfall in the number of sleep labs in a given area.

This shortfall may lead to delays in diagnosis and treatment initiation. In addition to the deficit in sleep labs, the cost for a PSG is high and may limit access to appropriate testing. Consequently, alternative strategies to PSG that can detect and measure the severity of the known risk factors for a crash are available. The aim in addressing this question was to determine whether alternative, low-cost technologies are available that can effectively detect and measure the severity of the known risk factors for a crash among individuals with OSA.

A number of portable sleep monitoring systems do offer an alternative method by which the severity of OSA may be assessed in a large number of individuals at a relatively low cost.

The Federal government’s analyses found that the diagnostic performance characteristics of most portable systems were reasonable. That is, the vast majority of available systems could differentiate individuals with OSA from those without, and they could differentiate individuals with severe OSA from those with mild-to-moderate disease better than would be expected by chance alone.



Which treatment has been shown to effectively reduce crash risk among individuals with OSA (as determined by crash rates or through indirect measures of crash risk)?
Continuous positive airway pressure (CPAP) reduces crash risk among individuals with moderate-to-severe OSA.

Other treatments may reduce crash risk among individuals with moderate-to-severe OSA, the available evidence to support this is not convincing. Consequently, we refrain from drawing further conclusions pertaining to other available technologies at this time. Alternatives to PAP therapy are available including, bariatric surgery , oropharyngeal surgery, facial bone surgery, tracheostomy. These treatments all require follow up and documentation of effectiveness. Oral appliances do not currently have a measurement of documenting compliance and for this reason alone are not included.



What is the length of time required following initiation of an effective treatment for patients with OSA to reach a degree of improvement that would permit safe driving (as determined by crash rates or through indirect measures of crash risk)?
The impact that CPAP has on crash-risk reduction among individuals with OSA can be seen after as little as one night of treatment. Exactly how many nights of treatment are required until CPAP exerts its maximum benefit is not known, but evidence suggests that this point has been reached prior to two weeks.



How soon, following cessation of an effective treatment (e.g., as a consequence of noncompliance), will individuals with OSA demonstrate reduced driver safety (as determined by crash rates or through indirect measures of crash risk)?
Cessation of CPAP leads to a decrease in simulated driving ability and increases in both OSA severity and daytime sleepiness. The rate at which this deterioration occurs cannot be determined; however, this deterioration may occur as soon as 24 hours following cessation of treatment.