ABS23: Diagnostic value of FEV1 measurements in the GP's office

Abstract

Aims and objectives:To determine whether office spirometry (pre- and post-BD FEV1 measurement by the GP with handheld spirometer) contributes to diagnosing obstructive airways disease in subjects with unexplained airway symptoms.Subjects and methods:15 GPs were instructed regarding FEV1 measurements and interpretation of spirometry and received a handheld spirometer. GPs performed office spirometry during or immediately after consultation in adults who presented with unexplained airway symptoms and recorded their diagnoses before and after office spirometry. Patients previously diagnosed with asthma or COPD were excluded. Within one week subjects underwent full spirometric testing in a lung function laboratory. Based on the laboratory test a pulmonologist labelled subjects as ‘obstructive’ or ‘not obstructive’. Sensitivity (Se), specificity (Sp), and Diagnostic Odds Ratio (DOR) were calculated for the GPs’ diagnosis of obstructive airways disease before and after office spirometry. The pulmonologists judgements served as ‘Gold standard’.Results:75 subjects were included (29 males). Mean age was 54 (SD 16) years. Initial GP diagnoses were: COPD/bronchitis (39%), asthma (36%), COPD/asthma (9%), and URTI (5%). Mean office spirometry post-BD FEV1 % predicted was 10.5% (SD 11.2) lower than for the laboratory test (p < 0.001). Before office spirometry the GPs’ diagnosis of COPD had a Se=56%, Sp=53% and DOR=1.47 (95%CI 1.35; 1.67). After office spirometry these values were Se=56% en Sp=76% and DOR=4.12 (95%CI 2.98; 7.47), respectively.Conclusions:Although office spirometry FEV1 values were significantly lower compared to laboratory values, the higher specificity and Diagnostic Odds Ratio indicate better diagnostic test characteristics of the GPs judgment when office spirometry is added in adults who present with unexplained airway symptoms. Conflict of interest and funding None. Funding: GlaxoSmithKline.