SOMERVILLE, Mass. A new study by an affiliate of the prestigious Harvard Medical School supports mandatory sleep apnea screenings for obese commercial vehicle drivers, including bus drivers, and a prohibition against "doctor shopping" by drivers to obtain their medical certification.

The study confirms previous findings that obesity-driven testing strategies identify commercial vehicle drivers with a high likelihood of obstructive sleep apnea and suggests that mandating sleep apnea treatment could reduce the risk of crashes.

"Commercial vehicle drivers with sleep apnea are much more likely to fall asleep at the wheel, and the condition is increasingly common as Americans become more obese," said Dr. Stefanos N. Kales, M.D., the study's senior author and medical director of employee and industrial medicine at Cambridge Health Alliance, a Harvard Medical School teaching affiliate.

"Additionally, we found that drivers who suffer from obstructive sleep apnea frequently underreport symptoms and diagnoses, and often do not follow through with sleep study referrals and sleep apnea treatment," Kales added.

The 15-month study examined 456 commercial drivers from more than 50 employers. At least 15 percent of the employer organizations operate passenger buses.

Seventy-eight (17 percent) of the drivers studied met the screening criteria for suspect obstructive sleep apnea. These drivers were older, more obese, and had a higher average blood pressure.

Of the 53 drivers who were referred for sleep studies, 33 did not comply with the referral and were lost to follow-up, Dr. Kales reported. The other 20 were confirmed to have obstructive sleep apnea but, after diagnosis, only one of these complied with treatment recommendations.

"It is very likely that most of the drivers who did not comply with sleep studies or sleep apnea treatment sought medical certification from examiners who do not screen for sleep apnea and are driving with untreated or inadequately treated sleep apnea," Kales said.

Obstructive sleep apnea is a syndrome characterized by sleep-disordered breathing, resulting in excessive daytime sleepiness, sleep attacks, psychomotor deficits, and disrupted nighttime sleep. It increases the risk of vehicular accidents by two- to seven-fold, and is common among commercial vehicle drivers.

In addition to being unrecognized or unreported by drivers, obstructive sleep apnea often remains undiagnosed by many primary care clinicians despite the fact sleep apnea increases the risks of hypertension, diabetes mellitus, and heart disease.

The studys authors noted that the Federal Motor Carrier Safety Administration is considering recommendations to require sleep apnea screening for all obese drivers based on body mass index, or BMI, which is a calculation based on height and weight.

"(Obstructive sleep apnea) screenings of commercial vehicle drivers will be ineffective unless they are federally mandated or required by employers," said Dr. Kales, who serves as an assistant professor at both Harvard Medical School and Harvard School of Public Health.

The study also supports a prohibition against doctor shopping. Said Dr. Kales: "Such action would prohibit drivers diagnosed with a serious disorder, that might limit driving or require treatment, to seek out more lenient or less rigorous medical examiners."

The study, "Screening for Obstructive Sleep Apnea During Commercial Driver Medical Examinations," was published by the Journal of Occupational and Environmental Medicine.

It was supported by the Federal Motor Carrier Safety Administration, a research award from the American College of Occupational and Environmental Medicine, and the National Institute for Occupational Safety and Health Education and Research Center.

For a copy of the study, contact David Cecere at Cambridge Health Alliance, phone (617) 503-8428, or e-mail dcecere@challiance.org.