Relationship between bronchial hyperreactivity and asthma remission during adolescence.
BACKGROUND
Many children with asthma outgrow this disease after the onset of puberty. However, the precise mechanism of outgrowing asthma in children is still unclear.


OBJECTIVE
To evaluate the characteristics of respiratory physiology during adolescence.


METHODS
The results of the lung function test and methacholine inhalation challenge were prospectively evaluated in adolescent patients with asthma with and without symptoms. One hundred sixty children with asthma participated. Twenty-eight children had symptom-free adolescent asthma (i.e., remission asthma) (boy to girl ratio, 16:12; mean age, 14.6 years), 25 had intermittent adolescent asthma (boy to girl ratio, 16:9; mean age, 14.9 years), and 47 had symptomatic adolescent asthma (boy to girl ratio, 27:20; mean age, 12.7 years). For comparison purposes, 60 younger children with symptomatic asthma participated. The parameters of bronchial hyperresponsiveness, baseline respiratory resistance, threshold of methacholine (Dmin) (bronchial sensitivity), and speed of bronchial constriction (Sm) (bronchial reactivity) were measured by methacholine inhalation challenge using the continuous oscillation method.


RESULTS
There was no significant difference in lung function results, such as forced vital capacity and forced expiratory volume in 1 second, between the intermittent asthma and the remission asthma groups. Also, there was no significant difference in baseline respiratory resistance and Dmin between the 2 groups. However, the value of Sm of the remission asthma group was significantly lower than that of the intermittent asthma group (P = .02) and the symptomatic asthma group (P = .02).


CONCLUSIONS
These data show that the adolescents with asthma remission showed a significant decrease of Sm, whereas Dmin was not changed. These results suggest one of the mechanisms by which asthma is outgrown in children and explain the common clinical aspects of adolescent asthma, such as symptom-free but bronchial hyperresponsive asthma.
Department of Pediatrics, Gunma University Graduate School of Medicine, Gunma, Japan. mochihi@med.gunma-u.ac.jp
Hiroyuki
H
Mochizuki
Reiko
R
Muramatsu
Satomi
S
Hagiwara
Satoru
S
Takami
Takahisa
T
Mizuno
Hirokazu
H
Arakawa
D000293:Adolescent; D041923:Adolescent Development / Q000502:physiology; D000367:Age Factors; D001249:Asthma / Q000453:epidemiology / Q000503:physiopathology*; D016084:Bronchoconstriction; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D011627:Puberty; D012075:Remission, Spontaneous; D014797:Vital Capacity; D055815:Young Adult
D016210:Methacholine Chloride