Asthma severity declines during adolescence
Severity of childhood asthma decreases towards adolescence, with equal trends for both males and females, according to a study presented at ATS 2018.
“We thought that the … decrease in asthma severity would be seen primarily in males, but [our study] shows equal improvement,” said lead author Ritika Gupta, a medical student from Case Western Reserve University School of Medicine in Cleveland, Ohio, US. “Both the prevalence of asthma and hospitalizations for asthma decreased between ages 12 and 30,” she added.
Using data from the SARP III* database, the researchers conducted a longitudinal prospective study involving 188 adolescent males (mean age 11.3 years, 57.3 percent) and females (mean age 11.8 years, 61.9 percent) who were diagnosed with severe asthma (defined using the ATS/ERS** 2014 criteria). Sputum collection, lung function test, symptom control questionnaires, and Tanner staging were performed to determine asthma severity. Patients were followed up over three visits within the first 2 months, and subsequent visits at 12, 24, and 36 months. [ATS 2018, abstract A7806]
Compared with asthma severity at baseline, a significantly lower incidence of severe asthma was observed in both males (57 percent vs 39 percent; p=0.0039) and females (62 percent vs 37 percent; p=0.0027) at 24 months of follow-up.
Similarly, at 36 months, the incidence of severe asthma was also significantly reduced compared with baseline (27 percent vs 57 percent; p=0.0004 for males and 31 percent vs 62 percent; p=0.0006 for females).
When the age component of severity was assessed separately, the researchers found that markers of asthma severity improved with asthma control questionnaire scores (p<0.0001), steroid taper response (p<0.0001), high-dose inhaled corticosteroid requirement at 3 and 6 months (p<0.0001 for both), and hospital admissions (p=0.0003). However, lung function and the need for oral corticosteroid therapy did not improve.
“There was no clear feature of children with severe asthma at enrolment that predicted whether or not their severe asthma will resolve … [but] there appears to be an ‘eye of the hurricane’ phenomenon in which hospitalizations of asthma and prevalence of asthma decrease between ages of 12 and 30, particularly in severe asthma. Our patient population, [aged 11 on average,] at the beginning of the study was heading straight into this period during the follow-up, which could explain the global decrease in asthma severity that we saw longitudinally,” said Gupta.
In addition, the decreased asthma severity during adolescence may be attributed to the baseline airway calibre and chest wall strength which increase as children age, noted Gupta. Enrolment in SARP could have also contributed to the decreased asthma severity due to close follow-up and monitoring, she added.
“Most components of severity improved longitudinally, with lung function as an exception. We believe that it will be important to follow this cohort longitudinally into the eye of the hurricane in order to determine the cause of this phenomenon,” Gupta said.
*SARP III: Severe Asthma Research Program III**ATS/ERS: American Thoracic Society/European Respiratory Society