Objective cough frequency, airway inflammation, and disease control in asthma

Marsden PA 1 , Satia I 2 , Ibrahim B 3 , Woodcock A 2 , Yates L 4 , Donnelly I 5 Show all authors , Jolly L 5 , Thomson NC 5 , Fowler SJ 6 , Smith JA 7

Affiliations 

  • 1 Centre for Respiratory Medicine and Allergy, University of Manchester, and Manchester Academic Health Science Centre, Manchester, England; University Hospital of South Manchester NHS Foundation Trust, Manchester, England; Lancashire Teaching Hospitals NHS Foundation Trust, Preston, England
  • 2 Centre for Respiratory Medicine and Allergy, University of Manchester, and Manchester Academic Health Science Centre, Manchester, England; University Hospital of South Manchester NHS Foundation Trust, Manchester, England
  • 3 Centre for Respiratory Medicine and Allergy, University of Manchester, and Manchester Academic Health Science Centre, Manchester, England; School of Pharmaceutical Sciences, Universiti Sains Malaysia, Penang, Malaysia
  • 4 Centre for Respiratory Medicine and Allergy, University of Manchester, and Manchester Academic Health Science Centre, Manchester, England
  • 5 Institute of Infection Immunity and Inflammation, University of Glasgow, Glasgow, Scotland
  • 6 Centre for Respiratory Medicine and Allergy, University of Manchester, and Manchester Academic Health Science Centre, Manchester, England; Lancashire Teaching Hospitals NHS Foundation Trust, Preston, England
  • 7 Centre for Respiratory Medicine and Allergy, University of Manchester, and Manchester Academic Health Science Centre, Manchester, England; University Hospital of South Manchester NHS Foundation Trust, Manchester, England. Electronic address: jacky.smith@manchester.ac.uk
Chest, 2016 06;149(6):1460-6.
PMID: 26973014 DOI: 10.1016/j.chest.2016.02.676

Abstract

BACKGROUND: Cough is recognized as an important troublesome symptom in the diagnosis and monitoring of asthma. Asthma control is thought to be determined by the degree of airway inflammation and hyperresponsiveness but how these factors relate to cough frequency is unclear. The goal of this study was to investigate the relationships between objective cough frequency, disease control, airflow obstruction, and airway inflammation in asthma.

METHODS: Participants with asthma underwent 24-h ambulatory cough monitoring and assessment of exhaled nitric oxide, spirometry, methacholine challenge, and sputum induction (cell counts and inflammatory mediator levels). Asthma control was assessed by using the Global Initiative for Asthma (GINA) classification and the Asthma Control Questionnaire (ACQ). The number of cough sounds was manually counted and expressed as coughs per hour (c/h).

RESULTS: Eighty-nine subjects with asthma (mean ± SD age, 57 ± 12 years; 57% female) were recruited. According to GINA criteria, 18 (20.2%) patients were classified as controlled, 39 (43.8%) partly controlled, and 32 (36%) uncontrolled; the median ACQ score was 1 (range, 0.0-4.4). The 6-item ACQ correlated with 24-h cough frequency (r = 0.40; P < .001), and patients with uncontrolled asthma (per GINA criteria) had higher median 24-h cough frequency (4.2 c/h; range, 0.3-27.6) compared with partially controlled asthma (1.8 c/h; range, 0.2-25.3; P = .01) and controlled asthma (1.7 c/h; range, 0.3-6.7; P = .002). Measures of airway inflammation were not significantly different between GINA categories and were not correlated with ACQ. In multivariate analyses, increasing cough frequency and worsening FEV1 independently predicted measures of asthma control.

CONCLUSIONS: Ambulatory cough frequency monitoring provides an objective assessment of asthma symptoms that correlates with standard measures of asthma control but not airflow obstruction or airway inflammation. Moreover, cough frequency and airflow obstruction represent independent dimensions of asthma control.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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