Clinical data discriminating between adults with positive and negative results on bronchodilator testing

To evaluate how spirometry, symptoms and smoking discriminate between subjects who are responsive to bronchodilator testing and those who are non-responsive, and to examine how cut-off points of positive tests are related to symptoms of chronic obstructive pulmonary disease (COPD) and asthma.

Subjects aged 47-48 and 71-73 years living in Bergen, Norway, were recruited. The 3506 participants (69%) filled in questionnaires and performed a bronchodilator test using salbutamol.

Tests were positive (forced expiratory volume in 1 s [Delta FEV1] >or=200 ml and >or=12%) in 107 subjects (3%). In logistic regression, spirometry (FEV1 < 80%, OR 6.0, 95%CI 3.6-10.2, and FEV1/FVC < 0.70, OR 3.1, 95%CI 1.9-5.2) and pack-years >or= 20 (OR 0.3, 95%CI 0.2-0.7), but not symptoms, predicted the test outcome. FEV1% and FEV1/forced volume capacity (FVC) discriminated equally well between positive and negative tests (area under the receiver operating characteristic [ROC] curve 0.81, 95%CI 0.77-0.85 vs. 0.77, 95%CI 0.72-0.82). The largest likelihood ratio for positive tests was 5.4 (95%CI 3.8-7.8) using FEV1 < 80% and FEV1/FVC < 0.70.

Spirometry and to a lesser extent smoking, but not symptoms, are useful in discriminating between middle-aged and elderly patients with positive and negative bronchodilator tests. Acute responses to salbutamol, expressed by commonly used Delta FEV1 cut-off points, are poorly related to COPD- and asthma-like symptoms.