CORONADO, CALIF. –
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“We have a good idea that obesity and asthma independently increase the risk of OSA, but a lot of the time in the pediatric population, these risk factors are found comorbid,” Ajay Narayanan at the Triological Society’s Combined Sections Meeting. “For this study we asked, how does the presence of asthma change the likelihood of having severe OSA in a cohort of obese patients? Knowing that both asthma and obesity independently increase the risk for OSA, we hypothesized that when they were comorbid, asthma would have a synergistic effect with obesity, causing severe OSA.”
Mr. Narayanan, a third-year student at the University of Texas Southwestern Medical Center, Dallas, and his colleagues performed a retrospective chart review of 367 children aged 9-17 years referred for a full-night polysomnography (PSG) for suspicion of having OSA. Demographic variables recorded included race, body mass index, rhinitis, gastroesophageal reflux disease, and tonsillar hypertrophy. Sleep variables recorded included apnea hypopnea index (AHI), sleep efficiency, rapid eye movement, and the peripheral capillary oxygen saturation (SpO2) nadir. The primary outcome was severe OSA defined as an AHI of 10 or greater on the PSG. They used logistic modeling to determine the association between asthma, obesity, and severe OSA.
The mean age of the study population was 14 years, 56% were male, and 43% were Hispanic. Of the 367 patients, 77 were neither obese nor asthmatic, 93 were nonobese but were asthmatic, 102 were obese but were nonasthmatic, and 95 were both obese and asthmatic. PSG results confirmed that obesity was associated with more signs of sleep apnea. For example, the nonobese, nonasthmatic group had a mean AHI of 11 events per hour, while the obese, nonasthmatic group had a mean AHI of 19 events per hour. “We observed a similar trend amongst our asthmatic population,” Mr. Narayanan said. “We observed an increase in the mean AHI amongst our asthmatic kids when we added obesity to the picture. Surprisingly, we found that asthma was associated with having fewer signs of sleep apnea.” Specifically, while the nonobese, nonasthmatic group had a mean AHI of 11 events per hour, those in the nonobese, asthmatic group had a mean of 5.6 events per hour (P = .005). “The finding was similar amongst our obese kids,” he said. “We saw a decrease in the mean AHI of our obese kids when we added asthma to the picture.”
On logistic regression analysis using obesity and asthma as independent variables, the researchers found that obesity increased the risk of severe OSA by 2.4-fold, but asthma decreased the odds of having severe OSA by about half (0.55). On multiple logistic regression controlling for commonly associated factors such as tonsillar hypertrophy, black race, and Hispanic ethnicity, obesity increased the risk of severe OSA by 2.2-fold, while asthma decreased the odds of having severe OSA by about half (0.51).
“In trying to explain this finding, we can turn to how these diseases are treated,” Mr. Narayanan said. “I say this because of the proven association between preexisting asthma and new onset OSA. Some of the reasons for this association include the tendency for airway collapsibility and systemwide inflammation seen in asthma, which then might contribute to the development of OSA. If we treat asthma symptoms early on, it might prevent the progression to sleep apnea down the line.”
Considering how prevalent comorbid asthma and OSA is, he continued, “we need to confirm that it is in fact well-controlled asthma that is associated with lowering the risk of severe OSA. Once we do this, we can ask the question: Can we use asthma pharmacotherapy to treat OSA? Some studies have shown that inhaled corticosteroids and montelukast (Singulair) may be effective treatment options for kids with OSA, but there’s definitely room for more research in this field, [such as determining] which patients would most benefit from this pharmacotherapy.” The researchers reported having no financial disclosures.
SOURCE: Narayanan A et al. Triological CSM, Abstracts.