Commercial truck drivers who get treatment for obstructive sleep apnea (OSA) for two years may reduce their crash risk to the level of drivers without apnea, a study from Italy suggests.

For professional drivers, the screening, treatment and management of sleep disorders should be mandatory to reduce accident risk and improve road safety, the study authors write in the journal Sleep Medicine.

"Screening for OSA in heavy vehicle drivers should be a major public safety priority," senior author Luigi Ferini-Strambi, director of the Sleep Disorders Center at Universita Vita-Salute San Raffaele in Milan, told Reuters Health.

"The study highlights the importance of a screening tool for sleep-related breathing disorders in commercial drivers' clinical routines," he said by email.

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Obstructive sleep apnea is a breathing disorder that interrupts the quantity and quality of sleep, causing fatigue and impaired attention, driving performance and reaction time. Medical studies associate OSA with heightened risk for hypertension, heart disease and stroke as well as daytime sleepiness and traffic accidents.

With OSA, a sleeper's airway collapses and breathing stops, often followed by gasping or choking that momentarily wakes the person, and this happens many times throughout the night. The condition is more common in men and obese people, and risk for it increases with age.

To see how much of a problem it is for commercial drivers carrying dangerous payloads, the researchers recruited among specially trained and regulated drivers who transport flammable materials like petroleum, diesel, propane and methane in northern Italy.

None of the 283 participants, all of them male, reported OSA symptoms at the beginning of the study. All filled out questionnaires, and based on their responses and other characteristics, researchers suspected 139 of them of having OSA. All of these suspected cases, and a portion of those not suspected to have OSA underwent sleep testing at home, which showed that more than a third of the drivers, 100 men, had obstructive sleep apnea.

The study team referred the 24 drivers with severe OSA to receive continuous positive airway pressure (CPAP), which keeps airways open during sleep. For two years, all these men used the treatment for at least four hours per night on at least five nights per week.

In the initial phase of the study, the researchers also analyzed all the drivers' survey responses about their past accidents and near-misses. They found that drivers with severe obstructive sleep apnea were 4.75 times more likely to be involved in near-miss accidents than non-OSA drivers.

After two years of treatment, the near-miss accidents dropped to a rate comparable to drivers without OSA. Only two drivers reported sleep-related accidents after treatment.

"Recently, untreated OSA among U.S. truck drivers was shown to increase the risk of serious, preventable accidents by five-fold," said Stefanos Kales of Harvard Medical School in Boston, who published the U.S. findings in March in the journal Sleep.

The Italian study uses more encompassing screening criteria with a higher sensitivity than the U.S. study did, which is important in showing how prevalent OSA is in truck drivers, said Kales, who was not involved in the current study.

In the U.S., commercial truck drivers must receive medical tests every two years to assess physical fitness to drive. However, the Federal Motor Carrier Safety Administration (FMCSA) doesn't require sleep apnea screening. In recent years, the National Transportation Safety Board (NTSB) has urged Department of Transportation agencies, including the FMCSA, to adopt mandatory screening for drivers.

"Recent data show definite increases in crash and accident risk with untreated OSA, which is the most common medical cause of daytime sleepiness," Kales told Reuters Health. "Transportation regulators need to take OSA seriously and mandate rigorous screening criteria, as well as procedures for diagnosis and ensuring treatment compliance."