成人・成長期ガイドライン：喘息・非喘息性好酸球性気管支炎による慢性咳嗽管理

喘息にしても、NAEBにしても治療としては、吸入ステロイド第1選択

cough variant asthmaに関する記載は"咳嗽は呼吸困難や喘鳴以外の喘息症状だが、単独でも存在することがある"という記述、咳嗽のみの症状の喘息

NAEBは、

background記載

「In a patient suspected  of having asthma as the primary cause of their chronic cough, but in whom physical examination and spirometry findings are non-diagnostic, bronchial challenge testing (e.g.,  methacholine inhalation test) should be performed to confirm the presence of airway hyperresponsiveness consistent with symptomatic asthma.
Asthma is also typically, but not  exclusively, associated with eosinophilic inflammation and non-invasive inflammatory  markers such as blood or sputum eosinophil counts and fractional exhaled nitric oxide , The wider application of non-invasive assessment of airway inflammation led in 1989 to the  identification of a condition that manifests as a corticosteroid responsive chronic cough in  non-smokers, without the variable airway obstruction or airway hyperresponsiveness that  characterize asthma, but with a airway eosinophilia. This condition was described as non- (FeNO) can provide additional evidence to support the need for corticosteroid treatment.」
The wider application of non-invasive assessment of airway inflammation led in 1989 (Gibson PG, Dolovich J, Denburg J, Ramsdale EH, Hargreave FE. Chronic cough: eosinophilic bronchitis without asthma. Lancet 1989; 1(8651): 1346-8.) to the identification of a condition that manifests as a corticosteroid responsive chronic cough in non-smokers, without the variable airway obstruction or airway hyperresponsiveness that characterize asthma, but with a airway eosinophilia.
This condition was described as non-asthmatic eosinophilic bronchitis (NAEB).

ということで、変動する気道閉塞やairway hyperresponsiveness が無いことが条件
気道過敏性試験がネックとなる




Managing Chronic Cough due to Asthma and NAEB in Adults and Adolescents: CHEST Guideline and Expert Panel Report
CHEST Expert Cough Panel
https://doi.org/10.1016/j.chest.2019.12.021
https://www.sciencedirect.com/science/article/abs/pii/S0012369220300453




1.In adult and adolescent patients with chronic cough due to asthma, we suggest that non-invasive measurement of airway inflammation has clinical utility and the presence of eosinophilic airway inflammation is likely to be associated with a more favorable response to corticosteroids (Grade 2B).

Remarks: The evidence supporting a role for non-invasive measurement of airway inflammation in asthma, especially severe asthma (ATS/ERS Guideline), in predicting a beneficial response to corticosteroids is moderate. However, cough-specific studies in asthma are limited as this symptom is not included as a specific symptom of asthma control and is generally not captured independently of other symptoms in most studies of asthma. 

2.  In adult and adolescent patients with chronic cough due to asthma as a unique symptom (cough variant asthma [CVA]) we suggest that inhaled corticosteroids should be considered as first line treatment. If response is incomplete in those with CVA or if cough is the  remaining isolated symptom following treatment with inhaled corticosteroids in patients with   asthma in whom cough was one of their symptoms we suggest stepping-up the inhaled corticosteroid dose and considering a therapeutic trial of a leukotriene inhibitor after  reconsideration of alternative causes of cough. Beta-agonists could also be considered in  combination with ICS. (Grade 1B).

Remarks: The evidence base supporting the step-wise treatment for asthma is very strong (as per the Global Initiative for Asthma, GINA), whereas cough-specific studies in asthma are  limited as this symptom is not captured independently of other symptoms in most studies of  asthma. The grade thus reflects the very strong evidence for step-wise treatment of asthma in   general rather than specifically for cough. 

3. In adult and adolescent patients with chronic cough due to non-asthmatic eosinophilic bronchitis (NAEB), we suggest inhaled corticosteroids as first-choice treatment (Grade 2B).

Remarks: There are very few therapeutic trials in NAEB and all include small numbers of  subjects, making this a weak recommendation.

4. In adult and adolescent patients with chronic cough due to NAEB if response to ICS is   incomplete, we suggest stepping-up the inhaled corticosteroid dose and considering a therapeutic trial of a leukotriene inhibitor after reconsideration of alternative causes of cough   (Grade 2C).

Remarks: There are very few therapeutic trials in NAEB and all include small numbers of subjects making this a weak recommendation.