Percentage fall in FVC at the provocative concentration of methacholine causing a 20% fall in FEV1 in symptomatic asthma and clinical remission during adolescence.
BACKGROUND
Many children with asthma go into long-term clinical remission at adolescence, but bronchial hyperresponsiveness (BHR) persists in approximately one half of these subjects. BHR is usually assessed by measuring the provocative concentration of methacholine causing a 20% fall in FEV1 (PC20). The percentage fall in FVC at the PC20 (deltaFVC) has been suggested to be a more useful index of disease severity in asthma than PC20.


OBJECTIVE
The aim of this study was to determine whether deltaFVC is higher in adolescents with symptomatic asthma than in those with clinical remission.


METHODS
Forty adolescents with symptomatic asthma and 80 adolescents with asthma remission underwent methacholine challenge testing. DeltaFVC and PC20 were measured on the methacholine dose-response curve.


RESULTS
The mean (95% confidence interval [CI]) deltaFVC (15.5% [95% CI, 14.1 to 16.9%]) in the symptomatic group (n = 40) was significantly higher (p = 0.017) than that (12.8% [95% CI, 11.5 to 14.1%]) in the BHR-positive (PC20 < 16 mg/mL) remission group (n = 44) or that (11.5% [95% CI, 10.2 to 12.8%]) of the BHR-negative remission group (n = 36), with no difference between the two latter groups (p = 0.581). No significant correlation was found between deltaFVC and PC20 in the symptomatic group (r = -0.156, p = 0.336) or in the whole remission group (r = -0.187, p = 0.097).


CONCLUSIONS
Adolescents with symptomatic asthma had a higher deltaFVC than those with clinical remission, irrespective of the presence of BHR in the latter group. This finding suggests that deltaFVC may serve as an adjunct marker for differentiating between asthma persistence and remission during adolescence.
Department of Pediatrics, Korea University Anam Hospital, Seoul.
Young
Y
Yoo
Department of Pediatrics, Seoul National University Hospital, Seoul, Korea.
Jinho
J
Yu
Department of Pediatrics, Seoul National University Hospital, Seoul, Korea.
Do Kyun
DK
Kim
Department of Pediatrics, Seoul National University Hospital, Seoul, Korea. Electronic address: kohyy@plaza.snu.ac.kr.
Young Yull
YY
Koh
D000293:Adolescent; D001249:Asthma / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D014797:Vital Capacity
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride