Sex-specific Effects of Asthma on Pulmonary Function in Children

Abstract

To evaluate the effects on lung function of asthma, time since diagnosis of asthma, and age at diagnosis of asthma, we examined school children in a cohort of 2,277 fourth- and seventh-graders at least twice during a 4-yr follow-up period. Sex-specific models for each lung function were fitted through mixed-effects models that used regression splines and captured age-dependent trends in the effect of asthma on lung function. In males, a history of asthma was associated with large and statistically significant deficits in maximum midexpiratory flow (MMEF) (-4.89%) and forced expiratory flow at 75% of expired FVC (FEF(75)) (-6.62%), whereas in females these deficits were smaller (-1.93% and -2.45%, respectively) and were not statistically significant. However, larger deficits were seen in both males and females with longer time since diagnosis. In males with more than 6 yr since diagnosis, there were significant deficits in FEV(1) (-3.91%), MMEF (-7.39%), FEF(75) (-8.12%), and peak expiratory flow rate (PEFR) (-4.65%) as compared with children with less than 3 yr since diagnosis. There were fewer females with more than 6 yr since diagnosis, but deficits were similar to those of males for FEV(1) (-2.52%), MMEF (-9.26%), and FEF(75) (-14.28%). Large deficits in flow rates in both large and small airways were observed in males and females for whom asthma was reported to have been diagnosed before age 3 yr. There was little evidence that lung growth in children with asthma "catches up" at older ages. Therefore, because a constant percent deficit in lung function implies an increasingly large absolute deficit in older children with larger lungs, these results are consistent with prior evidence that lung function deficits in children with asthma persist into adulthood. We also suggest that in children, commonly observed differences between sexes in the impact of asthma on lung function may reflect differences in the duration and age of onset of asthma in males and females.

Update on the roles of distal airways in asthma

“…In both males and females with longer time (.6 yr) since asthma diagnosis, larger deficits in forced expiratory flow between 25% and 75% of FVC (FEF25%-75%; -7% and -9%, respectively) and in FEF75% (-8% and -14%, respectively) were seen [55]. Similarly, in children for whom asthma was reported to have been diagnosed before age 3 yrs, FEF25-75% (-19% and -15%, respectively) and in FEF75% (-23% for both males and females) were markedly decreased [55]. In all cases, distal airway impairment was more pronounced than proximal airway impairment.…”

“…This impairment is more important when asthma has started early, before age 5 yrs, or when asthma is persistent. BERHANE et al [55] examined schoolchildren in a cohort of 2,277 fourth and seventh graders at least twice during a 4-yr follow-up period. In both males and females with longer time (.6 yr) since asthma diagnosis, larger deficits in forced expiratory flow between 25% and 75% of FVC (FEF25%-75%; -7% and -9%, respectively) and in FEF75% (-8% and -14%, respectively) were seen [55].…”

“…BERHANE et al [55] examined schoolchildren in a cohort of 2,277 fourth and seventh graders at least twice during a 4-yr follow-up period. In both males and females with longer time (.6 yr) since asthma diagnosis, larger deficits in forced expiratory flow between 25% and 75% of FVC (FEF25%-75%; -7% and -9%, respectively) and in FEF75% (-8% and -14%, respectively) were seen [55]. Similarly, in children for whom asthma was reported to have been diagnosed before age 3 yrs, FEF25-75% (-19% and -15%, respectively) and in FEF75% (-23% for both males and females) were markedly decreased [55].…”

Epidemiology of chronic obstructive pulmonary disease

“…There is, however, increasing evidence from wellconducted population surveys that asthmatics have a more rapid decline in FEV1 than nonasthmatics [82,83] and the excess decline is not trivial. In the Southern California cohort study a history of asthma was associated with a deficit in the maximum mid expiratory flow that was larger in male children than in female, although the influence of duration of asthma could not be excluded [84]. In addition, asthma in The Copenhagen Heart Study was associated with an increased mortality, primarily due to an increased COPD mortality [85].…”

Inhaled corticosteroids and growth of airway function in asthmatic children

“…Airways obstruction throughout childhood asthma may be due to factors such as diminished lung growth [24,25], enhanced bronchomotor tone and/or airway wall thickening and remodelling due to airway inflammation. A longitudinal study with maximal post-bronchodilator data would be required to look into diminished airway growth, taking into account any effects of anti-inflammatory drugs on lung growth.…”