Study objective: Coughing was studied in relation to different disorders and objective variables indicative of airway inflammation.
Setting: A random sample of 800 persons, aged 20 to 44 years, was chosen from a larger cohort of participants in the European Community Respiratory Health Survey in Uppsala Sweden; of these, 623 participated. This sample was enriched with 201 individuals who reported asthma-related symptoms or the use of asthma medication.
Methods: The study comprised a structured interview, including questions about habitual (productive and nonproductive) and nocturnal coughing and spirometry, methacholine challenge, peak flow diary, skin prick tests, and measurements of blood eosinophil count and serum eosinophil cationic protein (S-ECP).
Results: A significant positive correlation was found between productive coughing and asthma (adjusted odds ratios [OR] = 2.0), allergic rhinitis (OR = 1.9), gastroesophageal reflux (OR = 4.4), smoking (OR = 1.9), and anxiety (OR = 1.8), while nonproductive coughing was related to female gender (OR = 1.8) and anxiety (OR = 1.7). Nocturnal coughing was positively correlated to female gender (OR = 1.8), smoking (OR = 1.9), and asthma (OR = 2.2). Bronchial hyperresponsiveness was positively related to productive coughing (p < 0.001), nonproductive coughing, and nocturnal coughing (p < 0.05). S-ECP was significantly higher in individuals with nonproductive coughing compared with subjects without habitual coughing (p < 0.01).
Conclusions: We conclude that habitual coughing has a significant association with different disease categories.