Difficulties in differential diagnosis of COPD and asthma in primary care

Abstract

Chronic obstructive pulmonary disease (COPD) and asthma treatment must be based on appropriate diagnosis. However, patients receiving inhaled therapy in primary care may not be accurately diagnosed according to current guidelines. To analyse the characteristics of patients treated with inhaled medication, the concordance of tools for differential diagnosis, and the adequacy of prescription of inhaled corticosteroids (ICs) in primary care. Cross-sectional, multicentre, non-interventional study conducted in 10 primary care centres in Barcelona, Spain. Patients with chronic respiratory disease, aged >40 years were treated with ICs. They provided sociodemographic and clinical information and performed forced spirometry with a bronchodilator test (BDT). The diagnostic accuracy of asthma and COPD diagnoses were tested using two differential diagnosis questionnaires. A total of 328 patients were initially classified as having COPD (64.8%), asthma (15.4%), or indeterminate (19.8%) by their GPs. After spirometry, 40% of patients had moderate-severe airflow obstruction according to the GOLD classification; mean reversibility of forced expiratory volume in 1 second (FEV1) was 8.4%; 18.6% had a positive BDT; and 39.8% had post-bronchodilator FEV1/forced vital capacity >0.7. Concordance of the differential diagnosis tools was moderate (clinical diagnosis versus spirometry and between the two questionnaires), low (clinical diagnosis versus questionnaires), and very low (spirometry versus differential diagnosis). Of the patients diagnosed with COPD, 71.4% were treated with ICs, and 12% of those classified as having asthma were not receiving ICs. Most patients can be classified as having COPD or asthma by primary care physicians. The use of the two questionnaires did not provide a better differential diagnostic compared with symptoms and spirometry with a BDT. Misdiagnosis may lead to inadequate treatment.