Determinants of Lung Function Across Childhood in the Severe Asthma Research Program (SARP) 3

To identify clinical factors associated with low forced expiratory volume (FEV) 1 in children with asthma that may enhance prediction of low lung function that extends into adulthood.

The SARP 3 enrolled children and adults with severe asthma who met specific inclusion criteria as well as a comparison group of those with nonsevere asthma.

Clinical phenotypes and lung function was measured at baseline and longitudinally. The impact of baseline and time-varying predictors on prebronchodilator FEV 1 were assessed. The models were adjusted for age, predicted FEV 1, race, sex, and height. Secondary outcomes were postbronchodilator FEV 1 and prebronchodilator FEV 1/forced vital capacity.

Of participants, 111 children with severe asthma and 77 children with nonsevere asthma underwent a total of 862 spirometry assessments. FEV 1 was associated with baseline fractional exhaled nitric oxide, steroid responsiveness, and maximal bronchodilator reversibility. Age, obesity, and exacerbation frequency were predictive of FEV 1 over time, with a significant age and sex interaction. Although girls showed no exacerbation effect, boys with moderate (1–2 in the past year) and high (≥3 in the past year) exacerbation frequencies experienced declines in FEV 1 with each successive year.

Baseline fractional exhaled nitric oxide, steroid responsiveness, maximum bronchodilator reversibility, and obesity were associated with lower FEV 1 over time in children with severe and nonsevere asthma. The study also revealed a sex-specific risk, with boys experiencing a negative impact of exacerbations on lung function throughout childhood.

Children with asthma are at risk for low lung function into adulthood. This study identifies children who are most at-risk for this decline and underscores the need for efforts to identify interventions and therapeutic approaches that will modify the trajectory of this common disease.