Background: Chronic obstructive pulmonary disease (COPD) is an under-diagnosed condition. General practitioners meet and examine the patients in early stages of the disease, and symptoms represent the starting point of the diagnostic process.
Aim: To evaluate the diagnostic value of respiratory symptoms in the diagnosis of airflow limitation.
Methods: Spirometry was performed in a cross-sectional population-based study of 3954 subjects 60 years and older (54.5% women), who also filled in a questionnaire on symptoms.
Results: The prevalence of any airflow limitation was 15.5% and 20.8%, in women and men, respectively, whereas the corresponding prevalence of severe airflow limitation (FEV(1)<50% predicted) was 3.4% and 4.9%. The positive predictive value of chronic cough with phlegm for any airflow limitation was 37.0% in women and 40.4% in men, and 17.3% and 14.2%, respectively, for severe airflow limitation. Wheezing was a symptom which persisted despite smoking cessation, whereas coughing was considerably less common in ex-smokers than in current smokers. Wheezing, dyspnoea on unhurried walking, dyspnoea on quick walking, and coughing with phlegm were independent predictors of any airflow limitation, OR 1.5, 1.8, 1.4, and 1.6 respectively. (The ORs for severe airflow limitation were 2.4, 2.4, 2.4, and 1.6 respectively.) To be an ex-smoker (OR 2.4) or a current smoker (OR 5.8) was of greater importance. In never- and ex-smokers the chance of having airflow limitation was almost doubled when having two or more, compared with one, of the three symptoms: wheezing, dyspnoea, and coughing with phlegm. Ex-smokers reporting two symptoms had a similar risk of airflow limitation to current smokers not reporting any symptoms.
Conclusion: Respiratory symptoms are valuable predictors of airflow limitation and should be emphasized when selecting patients for spirometry.