Relationship between duration of disease and bronchial responsiveness in 6-8 years old children with asthma

PURPOSE: Bronchial hyperresponsiveness is considered as a hallmark of asthma. The duration of asthma was demonstrated to be associated with bronchial responsiveness, expressed as methacholine PC20. We investigated the relationship between duration of asthma and percentage fall in forced vital capacity (FVC) at PC20 (DeltaFVC), another index of bronchial responsiveness, which reflects excessive bronchoconstriction. METHODS: Six- to 8-year-old children with asthma underwent methacholine inhalation test. The PC20 and DeltaFVC were calculated for each individual. The subjects were classified into those with wheezing onset in the first three years of life (early-onset asthma [EA], n=63) and those with wheezing onset from three years onwards (late-onset asthma [LA], n=99). RESULTS: From the time of wheezing onset, duration of asthma ranged from 0.2 to 8.3 years. The mean duration of asthma in patients with EA was 5.6 years (standard deviation [SD], 1.2 years), compared with 2.2 years (SD, 1.3 years) in the patients with LA. Patients with EA had a significantly lower forced expiratory volume in 1 second/FVC than did those with LA (84.6%+/-5.9% vs. 86.8%+/-5.1%, P<0.05). The DeltaFVC was significantly higher in patients with EA than in those with LA (19.4%+/-5.1% vs. 17.0%+/-4.5%, P<0.01), but PC20 was not different between the two groups. In total subjects, asthma duration correlated significantly with DeltaFVC (r=0.222, P<0.01), but not with PC20. CONCLUSION: These data suggest that prolonged asthma is associated with worsened bronchial responsiveness during childhood, and such an association may be reflected primarily by DeltaFVC rather than PC20.

Relationship between deltaFVC (% fall in FVC at the PC20 Dose of Methacholine) and Serum Eosinophil Cationic Protein (ECP) in 6-8 Year Old Children with Asthma / 소아과

PURPOSE: Bronchial hyperresponsiveness (BHR) is considered a hallmark of asthma. Increased levels of eosinophil cationic protein (ECP) have been identified in serum of asthma patients. Several studies have examined the relationship between serum ECP and bronchial responsiveness, expressed as methacholine PC20 in asthmatic patients, with conflicting results. The aims of this study were to examine the relationship between serum ECP and deltaFVC, another index of bronchial responsiveness, which reflects increased maximal airway response. METHODS: Six to 8-year-old children with asthma (n=109) underwent methacholine bronchoprovocation testing. The PC20 dose of methacholine and deltaFVC were calculated for each individual from the methacholine dose response curves. Serum ECP levels and blood total eosinophil counts were also measured. RESULTS: Serum ECP correlated with deltaFVC (r=0.217, P=0.023), as well as PC20 (r=-0.208, P=0.030). However, blood eosinophil counts failed to show any correlations with deltaFVC (r=0.085, P=0.378) or PC20 (r=-0.148, P=0.125). deltaFVC did not correlate with PC20 (r=-0.079, P=0.417). CONCLUSION: Blood eosinophil activation is associated with both components of BHR including increased sensitivity and increased maximal response in 6-8 year old children with asthma.

Comparison of Obesity between Children with Asthma and Healthy Children / 소아알레르기및호흡기학회지

PURPOSE: An increase in the prevalence of obesity and asthma over recent decades has been reported. While there is evidence of a positive association between asthma and obesity, there is no report about association between asthma and obesity in Korea. The aim of this study was to determine if obesity is more prevalent in children with asthma compared with healthy children and to determine if obesity is associated with atopy in children with asthma. METHODS: We studied 291 atopic asthmatic children, 85 nonatopic asthmatic children and 149 healthy children. BMI (kg/m2) and obesity index were calculated using height and weight which were measured on the same day of methacholine challenge test. Obesity was defined as percentile of BMI over 95 percentile. BMI, obesity index and prevalence of obesity were compared among the three groups. Association between obesity and PC20 was also assessed in asthmatics. RESULTS: The prevalence of obesity was similar for atopic asthmatic group (11.6%), nonatopic asthmatic group (11.7%) and healthy group (12.7%). The prevalence of being at risk of overweight was similar for atopic asthmatic group (18.2%), nonatopic asthmatic group (24.7%) and healthy group (18.1%). There was no difference in BMI and obesity index among the three groups. In asthmatics, obesity index was not correlated with PC20 and there was no difference in obesity index among the asthmatics classified by PC20; < 2 mg/mL, 2-8 mg/mL, 8-18 mg/mL. CONCLUSION: These results suggest that obesity is not associated with asthma. Further studies are needed to confirm these findings in general population, and a prospective study is needed to follow younger children through adolescence.

Blood Eosinophil and Serum Eosinophil Cationic Protein as a Marker of Bronchial Hyperresponsiveness in Children with Suspected Asthma

PURPOSE: Airway inflammation is considered to be a characteristic feature of asthma, and eosinophils are recognized as the most important inflammatory cells. This study aims to assess the importance of blood eosinophil count and serum eosinophil cationic protein(ECP) levels as a non- invasive marker of bronchial hyperresponsiveness(BHR) in children with suspected asthma. METHODS: This study used data from 87 subjects with asthma-like symptoms(6-18 years old). The FEV1 and provocative concentration producing a 20% fall in FEV1(PC20) on methacholin inhalation challenge test were measured. Four groups were classified based on PC20[Group I : <2 mg/ mL; Group II : 2-8 mg/mL; Group III : 8-18 mg/mL; Group IV : (18 mg/mL), and blood eosinophil count and serum ECP levels were analyzed. In addition, subjects were classified based on the cutoff value of PC20(BHR positive group : <18 mg/mL; BHR negative group : (18 mg/mL). Then blood eosinophil count and serum ECP level were compared between these two groups. RESULTS: Likelihood ratio test for trends revealed a significant association between the blood eosinophil count or serum ECP level, and the degree of BHR as measured by methacholine PC20. Blood eosinophil count or serum ECP level was significantly higher in the BHR(+) group than in the BHR(-) group. Blood eosinophil count had a positive correlation with serum ECP level. CONCLUSIONS: Blood eosinophil count and serum ECP level may be a useful non-invasive clinical marker of BHR in subjects with suspected asthma. This supports the hypothesis that BHR in asthma is a consequence of airway eosinophilic inflammation.

Correlation of Exercise-Induced Bronchoconstriction to PC20 and Maximal AirwayNarrowing on the Dose-Response Curve to Methacholine / 결핵

BACKGROUND: Exercise is one of the most common precipitants of acute asthma encountered in clinical practice. The development of airflow limitation that occurs several minutes after vigorous exercise, i. g. exercise-induced bronchoconstriction(EIB), has been shown to be closely correlated with the nonspecific bronchial hyperresponsiveness, which is the hallmark of bronchial asthma. All previous reports that assessed the correlation of EIB to nonspecific bronchial hyperresponsiveness have focused on airway sensitivity(PC20) to inhaled bronchoconstrictor such as methacholine or histamine. However, maximal airway narrowing(MAN), reflecting the extent to which the airways can narrow, when being exposed to high dose of inhaled stimuli, has not been studied in relation to the degree of EIB. METHODS: Fifty-six children with mild asthma(41 boys and 15 girls), aged 6 to 15 years(mean +/- SD, 9.9 +/- 2.5 years) completed this study. Subjects attended the laboratory on two consecutive days. Each subject performed the high-dose methacholine inhalation test at 4 p.m. on the first day. The dose-response curves were characterized by their position(PC20) and MAN, which was defined as maximal response plateau(MRP: when two or three data points of the highest concentrations fell within a 5% response range) or the last of the data points(when a plateau could not be measured). On the next day, exercise challenge, free running outdoors for ten minutes, was performed at 9 a.m.. FEV1 was measured at graduated intervals, 3 to 10 minutes apart, until 60 minutes after exercise. Response(the maximal DeltaFEV1 from the pre-exercise value) was classified arbitrarily into three groups; no response ((-) EIB: DeltaFEV1 20%). RESULTS: 1) When geometric mean PC20 of the three groups were compared, PC20 of (+) EIB group was significantly lower than that of (-)EIB group. 2) There was a close correlation between PC20 and the severity of EIB in the whole group(r= -0.568, p<0.01). 3) Of the total 56 subjects, MRP could be measured in 36 subjects, and the MRP of these subjects correlated fairly with the severity of EIB(r= 0.355, p<0.05) 4) The MAN of (+) EIB group was significantly higher than that of (-)EIB group(p<0.01). 5) The MAN correlated well with the severity of EIB in the whole group(r=0.546, p<0.01). CONCLUSION: The degree of MAN as well as bronchial sensitivity (PC2o) to methacholine is correlated well with the severity of EIB. The results suggest that the two main components of airway hyperresponsiveness may be equally important determinants of exercise reactivity, although the mechanism may be different from each other. The present study also provides further evidence that EIB is a manifestation of the increased airway reactivity characteristic of bronchial asthma.