Identifying asthma and chronic obstructive pulmonary disease in patients with persistent cough presenting to general practitioners: descriptive study

Abstract

Abstract Objective: To determine the prevalence of asthma and chronic obstructive pulmonary disease in patients not known to have these disorders, who present in general practice with persistent cough, and to ascertain criteria to help general practitioners in diagnosis. Design: Descriptive study. Setting: Primary healthcare centre in the Netherlands. Subjects : 192 patients aged 18-75 years, not known to have asthma or chronic obstructive pulmonary disease, attending their general practitioner with cough persisting for at least 2 weeks. Methods : A diagnosis of asthma or chronic obstructive pulmonary disease was based on the recurrence of airway symptoms in the past year accompanied by spirometric measurements (including bronchodilator testing) and methacholine provocation tests. A scoring formula to estimate the probability of asthma or chronic obstructive pulmonary disease, based on history and physical examination, was generated by means of logistic regression. Results : 74 patients (39%) were classified as having asthma, 14 (7%) as having chronic obstructive pulmonary disease. The best formula for predicting asthma or chronic obstructive pulmonary disease used scores for three symptoms: (reported) wheeze,(reported) dyspnoea, and allergen induced symptoms, together with prolonged expiration, pack years of smoking, and female sex. Variables were scored 1 when present and 0 when absent, except for allergen induced symptoms (1.5) and number of pack years of smoking (n/25). With a cut off value of 3 on the scoring formula, 76% of the patients could be classified correctly. Conclusions : About half of patients with persistent cough who present to a general practitioner have asthma or chronic obstructive pulmonary disease. With a simple formula based on three symptoms and prolonged expiration, pack years of smoking, and female sex, most patients may be identified correctly in general practice. Key messages Nearly half the patients attending a general practitioner with persistent cough show features of asthma or chronic obstructive pulmonary disease (significant bronchodilator response, airway obstruction, or hyperresponsiveness) Most cases can be identified through history taking and physical examination only The key variables to predict which patients are likely to have asthma or chronic obstructive pulmonary disease are: current wheeze and dyspnoea, symptoms elicited by allergens, prolonged expiration, cumulative smoking, and female sex The scoring formula composed of the key variables may help to determine when it is necessary to perform pulmonary function testing to confirm or reject a diagnosis of asthma or chronic obstructive pulmonary disease