Relationship between methacholine PC20 level and asthma control status among pediatric patients with atopic asthma

ABSTRACT

PURPOSE: Although methacholine PC20 helps clinicians to identify asthma, there are practical limitations in using methacholine PC20 to assess asthma control. We assessed the relationship between methacholine PC20 levels and asthma control status in child patients with atopic asthma. METHODS: We enrolled 153 children of 8 to 15 years of age with atopic asthma and measured methacholine PC20 of these children when their asthma was controlled. We followed up these patients for more than 2 years with measurements of asthma control score, lung function, bronchodilator response (BDR), and fractional exhaled nitric oxide (FeNO). RESULTS: The geometric mean of methacholine PC20 in the study population was 2.81 mg/mL. Lower methacholine PC20 was found to be associated with lower lung function, higher rate of BDR greater than 12%, higher level of BDR, higher rate of FeNO levels greater than 23 ppb, higher FeNO, higher numbers of asthma aggravation per year, and higher rate of asthma control test scores of 19 or less. CONCLUSION: These data provide evidences that the degree of methacholine PC20 is linked to disease severity in children with atopic asthma. Thus, regular and close monitoring of asthma control should be required for patients with lower levels of methacholine PC20.