Study Identifies Risk Factors for Obstructive Sleep Apnea

While obstructive sleep apnea syndrome (OSAS) is a relatively common condition, affecting about 2 percent to 4 percent of young children, the scientific community is just opening its eyes to pediatric sleep disorders. Little is known, for example, about the characteristics that increase OSAS severity in children.

OSAS occurs when a child stops breathing during sleep, usually because there is a blockage from enlarged tonsils or adenoids. Many of the pauses, called apneas and hypopneas, cause a brief arousal that increases muscle tone, opens the airway, and allows the child to resume breathing. These repeated disruptions result in restless sleep. Recurrent nightly episodes of obstructive apnea are associated with adverse behavioral, cognitive, quality of life, and health outcomes in children.

Researchers from the Sleep Center at The Children’s Hospital of Philadelphia were involved with a large, multicenter study called the Childhood Adenotonsillectomy Study for Children With OSAS (CHAT), and recently they used the study’s baseline data to perform a cross-sectional screening to analyze which factors predict OSAS severity. They examined data from 421 children ages 5 to 9 years who had undergone sleep testing, known as polysomnography, and evaluated the relationship between their levels of OSAS to sex, race, body mass index, environmental tobacco smoke (ETS), prematurity, socioeconomic variables, and comorbidities.

“If presumably you know some of the risk factors, you might be able to address some of those risk factors and preempt the sleep apnea or at least diagnosis it earlier,” said Carole L. Marcus, MBBCh, director of CHOP’s Sleep Center, who was first author for the CHAT study and also participated in the auxiliary study that appeared in SLEEP in February.

The auxiliary study found that African American race predicted OSAS severity, which supports previous research. This is especially interesting, Dr. Marcus said, because the CHAT study results showed that African American children had less improvement postoperatively, both in terms of polysomnographic changes and behavioral changes. Much debate exists about why African American race would be associated with higher OSAS severity and poorer outcomes after surgery, but some research suggests genetic, craniofacial, and environmental components play a role.

“They have worse disease, but they don’t respond as well to the therapy and possibly have more complications from the treatment,” Dr. Marcus said. “That definitely deserves further research. We also found in another related study that looked at continuous positive airway pressure, which is an alternative therapy for kids who don’t improve following surgical therapy, that they had poor adherence to CPAP. So they’re definitely a more difficult group to treat.”

Study participants’ exposure to secondhand smoke was another significant risk factor for increased OSAS severity that researchers identified.  ETS already has been connected to snoring in children, so this novel finding advances pediatric sleep research by demonstrating its effect on OSAS.

African American race and exposure to ETS were each associated with an approximately 20 percent increase in apnea-hypopnea index. More research is needed, Dr. Marcus said, to define these specific factors and suggest better OSAS screening strategies that focus on African American children and children exposed to ETS.

In the meantime, pediatricians can use this study’s findings to promote awareness of OSAS by asking parents about snoring at their children’s regular healthcare maintenance visits, Dr. Marcus said. It also provides an ideal opportunity to encourage families with smokers to quit and protect their children from secondhand smoke.