Blood eosinophils as a predictor of treatment response in adults with difficult-to-treat chronic cough.

There is lack of evidence on the role of blood eosinophil count (BEC) as a predictor of treatment response in patients with chronic cough. The study aimed to evaluate BEC as a predictor of treatment response in all non-smoking adults with chronic cough and normal chest radiograph referred to cough clinic and in a subgroup of patients with chronic cough due to asthma or non-asthmatic eosinophilic bronchitis (NAEB). This prospective cohort study included 142 consecutive, non-smoking patients referred to our cough centre due to chronic cough. The management of chronic cough was performed according to the current recommendations. At least a 30-mm decrease of 100-mm visual analogue scale in cough severity and a 1.3 points improvement in Leicester Cough Questionnaire were classified as a good therapeutic response. There was a predominance of females (72.5%), median age 57.5 years with long-lasting, severe cough (median cough duration 60 months, severity 55/100 mm). Asthma and NAEB were diagnosed in 47.2% and 4.9% of patients, respectively. After 12-16 weeks of therapy, a good response to chronic cough treatment was found in 31.0% of all patients. A weak positive correlation was demonstrated between reduction in cough severity and BEC (r=0.28, p<0.001). Area under the curve for all patients with chronic cough was 0.62 with the optimal BEC cut-off for prediction of treatment response set at 237 cells·µL-1 and for patients with chronic cough due to asthma/NAEB was 0.68 (95% CI 0.55-0.81) with the cut-off at 150 cells·µL-1. BEC is a poor predictor of treatment response in adults with chronic cough treated in the cough centre.

Rybka-Fraczek A ，Dabrowska M ，Grabczak EM ，Bialek-Gosk K ，Klimowicz K ，Truba O ，Nejman-Gryz P ，Paplinska-Goryca M ，Krenke R ... -  《ERJ Open Research》

Managing Chronic Cough Due to Asthma and NAEB in Adults and Adolescents: CHEST Guideline and Expert Panel Report.

Asthma and non-asthmatic eosinophilic bronchitis (NAEB) are among the commonest causes of chronic cough in adults. We sought to determine the role of non-invasive measurements of airway inflammation, including induced sputum and fractional exhaled nitric oxide, in the evaluation of cough associated with asthma, and what the best treatment is for cough due to asthma or NAEB. We undertook three systematic reviews of randomized controlled trials and observational trials of adults and adolescents > 12 years of age with a chronic cough due to asthma or NAEB. Eligible studies were identified in MEDLINE, CENTRAL, and SCOPUS and assessed for relevance and quality. Guidelines were developed and voted upon using CHEST guideline methodology. Of the citations reviewed, 3/1,175, 53/656, and 6/134 were identified as being eligible for inclusion in the three systematic reviews, respectively. In contrast to established guidelines for asthma therapies in general and the inclusion in some guidelines for a role of biomarkers of airway inflammation to guide treatment in severe disease, the evidence of specific benefit related to the use of non-invasive biomarkers in patients with chronic cough due to asthma was weak. The best therapeutic option for cough in asthma or NAEB is inhaled corticosteroids followed by leukotriene receptor antagonism. This guideline offers recommendations on the role of non-invasive measurements of airway inflammation and treatment for cough due to asthma or NAEB based on the available literature, and identifies gaps in knowledge and areas for future research.

Côté A ，Russell RJ ，Boulet LP ，Gibson PG ，Lai K ，Irwin RS ，Brightling CE ，CHEST Expert Cough Panel ... -  《-》

Non-asthmatic eosinophilic bronchitis and its relationship with asthma.

Non-asthmatic eosinophilic bronchitis (NAEB) is an important cause of chronic cough. NAEB shares similar eosinophilic inflammation of airway and response to corticosteroids with asthma. However, in contrast to asthma, NAEB subjects have no airflow obstruction and airway hyperresponsiveness. The pathogenesis of NAEB are involved with many inflammatory cells such as eosinophils, lymphocytes, mast cells, cytokines and inflammatory mediators, includingTh2 cytokines, histamine, leukotrines, prograndins and oxidative stress. The different locations of inflammatory cells and the inflammatory mediators level may explain this difference between EB and asthma. There is no study on dose and duration of treatment. On the prognosis of NAEB, long term follow-up study suggested that NAEB should be a distinct entity rather than an early stage of asthma or COPD. The relapse rate is high after treatment. Assessing sputum eosinophils after treatment is useful to identify those at risk of relapse.

Lai K ，Chen R ，Peng W ，Zhan W ... -  《-》

Eosinophilic airway inflammation is common in subacute cough following acute upper respiratory tract infection.

Patients presenting with refractory postinfectious cough may respond to glucocorticosteroids but it is unclear whether airway eosinophilic inflammation exists in those patients. We aimed to determine the airway inflammation and causes of subacute cough following acute upper respiratory tract infection (AURTI). One hundred and sixteen patients with persistent cough lasting 3-8 weeks after upper respiratory tract infection were evaluated with differential cell count in induced sputum, spirometry and methacholine bronchial challenge testing. In patients with subacute cough, sputum eosinophilia (median 8.5%,3.0-73.0%) was identified in 35 (33.6%) patients, 22 (18.5%) without bronchial hyperresponsiveness (BHR) were diagnosed as non-asthmatic eosinophilic bronchitis (NAEB), 13 (14.3%) of whom with BHR were diagnosed as cough variant asthma (CVA). Cough in patients with sputum eosinophilia improved after treatment with corticosteroids. Compared with postinfectious cough (PIC) and NAEB, CVA had significantly higher median eosinophil count in induced sputum (0.5% vs 7.5% vs 20.0%, P < 0.01). MMEF in CVA was significantly lower than PIC and NAEB (P < 0.05). The common causes of subacute cough following acute upper respiratory tract infection (AURTI) were PIC (37.8%), NAEB (18.5%), CVA (14.3%) and upper airway cough syndrome (UACS) (10.1%). Atopic cough (AC) (5.2%) and gastroesophageal reflux-related cough (GERC) (3.4%) were less common in subacute cough following AURTI, while 9 (7.8%) patients had unexplained cough. Subacute cough following AURTI can be attributed to different entities, eosinophilic airway inflammation is common. Induced sputum should be considered when evaluating patients with subacute cough following acute upper respiratory tract infection.

Lai K ，Lin L ，Liu B ，Chen R ，Tang Y ，Luo W ，Chen Q ... -  《-》

Exhaled nitric oxide measurement is useful for the exclusion of nonasthmatic eosinophilic bronchitis in patients with chronic cough.

Oh MJ ，Lee JY ，Lee BJ ，Choi DC ... -  《CHEST》