Physiological and radiological characterisation of patients diagnosed with chronic obstructive pulmonary disease in primary care

Abstract

BACKGROUND Chronic obstructive pulmonary disease (COPD) is common although often poorly characterised, particularly in primary care. However, application of guidelines to the management of such patients needs a clear understanding of the phenotype. In particular, the British guidelines for the management of COPD recommend that the diagnosis is based on appropriate symptoms and evidence of airflow obstruction as determined by a forced expiratory volume in one second (FEV₁) of <80% of the predicted value and an FEV₁/VC ratio of <70%.

METHODS A study was undertaken of 110 patients aged 40–80 years who had presented to their general practitioner with an acute exacerbation of COPD. The episode was treated at home and, when patients had recovered to the stable state (two months later), they were characterised by full lung function tests and a high resolution computed tomographic (HRCT) scan of the chest.

RESULTS There was a wide range of impairment of FEV₁ which was in the normal range (≥80%) in 30%, mildly impaired (60–79%) in 18%, moderately impaired (40–59%) in 33%, and severely impaired (<40%) in 19% of patients. A reduced FEV₁/VC ratio was present in all patients with an FEV₁ of <80% predicted but also in 41% of those with an FEV₁ of ≥80% predicted. Only 5% of patients had a substantial bronchodilator response suggesting a diagnosis of asthma. Emphysema was present in 51% of patients and confined to the upper lobes in most (73% of these patients). HRCT evidence of bronchiectasis was noted in 29% of patients and was predominantly tubular; most (81%) were current or ex-smokers. A solitary pulmonary nodule was seen on 9% of scans and unsuspected lung malignancy was diagnosed in two patients.

CONCLUSIONS This study confirms that COPD in primary care is a heterogeneous condition. Some patients do not fulfil the proposed diagnostic criteria with FEV₁ of ≥80% predicted but they may nevertheless have airflow obstruction. Bronchiectasis is common in this group of patients, as is unsuspected malignancy. These findings should be considered when developing recommendations for the investigation and management of COPD in the community.