Sleep-Disordered Breathing Is Associated With Asthma Severity in Children
Dr Gowher Yusuf
Hal 3rd stage, Bengaluru Jul 29, 2017
(Source: Ross KR, Storfer-Isser A, Hart MA, et al. J Pediatr. 2012; 160:736-7420)
Ross and colleagues evaluated correlations among obesity, sleep-disordered breathing (SDB), and asthma severity in a cohort of children referred to a pediatric asthma specialty clinic. The children were 4-18 years old, had been diagnosed with asthma by a pediatric pulmonologist, and were evaluated at 1 medical center from 2006 to 2008. Children with chronic medical conditions in addition to asthma, such as cystic fibrosis or other chronic diseases, were excluded. Those with 1 positive skin test were classified as having allergic sensitization. Data also included medication use during the study period, standardized measures of asthma control, number of systemic steroid courses required, unscheduled physician visits for asthma, emergency department visits or hospitalizations for asthma, and school attendance.
Children were followed for 6-12 months in the clinic. At the end of the study period, the children were classified as having "severe" asthma (or not) for purposes of completing the correlation analyses. Children were considered to have severe asthma if they had a symptom score above a predetermined level, had a complex controller regimen, required systemic corticosteroids 3 or more times during the study period, or had 2 or more hospitalizations. Children could also be labeled as having severe asthma if they made 3 or more outpatient or emergency department visits for asthma.
The investigators were primarily interested in 2 potential predictors of asthma severity: obesity and SDB. Obesity was defined as a body mass index (BMI) greater than the 95th percentile and SDB was defined as habitual snoring (as determined by parents to occur at least 3 times per week) along with 3 or more desaturation episodes on overnight pulse oximetry monitoring when the children were reported to be well. The primary outcome of interest was whether SDB and/or obesity had independent predictive influence on being classified as having severe asthma.
The investigators interpreted the findings to mean that SDB is a more significant problem for children with higher BMI. Children with normal BMI and SDB did not have significantly higher odds of having severe asthma, whereas those with BMI z-scores ≥ 2.0 had a 6.7 times higher odds of having severe asthma. Ross and colleagues concluded that SDB is a potentially modifiable risk factor that contributes to severe asthma. The investigators also acknowledged that they failed to prove the hypothesis that obesity alone was associated with asthma severity.
These may be some of the first data to demonstrate that SDB in children can contribute to asthma severity. Although the study did not evaluate whether addressing SDB directly or indirectly through loss of weight would improve asthma severity, their discussion reviews many of the biological mechanisms through which this should be possible. The detrimental effects of SDB including effects on academic performance, and the cardiovascular effects of overweight and obesity are well-documented. These data suggest that SDB is a comorbidity that should be considered when evaluating poor asthma control in an overweight or obese child.