Background: The importance of identifying chronic obstructive pulmonary disease (COPD) at an early stage is recognised. Improved and easily accessible identification of individuals at risk of COPD in primary care is needed to select patients for spirometry more accurately.
Aims: To explore whether use of a mini-spirometer can predict a diagnosis of COPD in patients at risk of COPD in primary care, and to assess its cost-effectiveness in detecting patients with COPD.
Methods: Primary care patients aged 45-85 years with a smoking history of >15 pack-years were selected. Data were collected on the Clinical COPD Questionnaire (CCQ), Medical Research Council (MRC) dyspnoea scale and smoking habits. Lung function (forced expiratory volume in 1 and 6 s; FEV1 and FEV6, respectively) was measured by mini-spirometer (copd-6), followed by diagnostic standard spirometry (COPD diagnosis post-bronchodilation ratio of FEV1 to forced vital capacity (FVC) <0.7). Time consumed was recorded. Univariate logistic regression and receiver operating characteristic (ROC) curves were used.
Results: A total of 305 patients (57% females) of mean (SD) age 61.2 (8.4) years, mean (SD) total CCQ 1.0 (0.8) and mean (SD) MRC 0.8 (0.8) were recruited from 21 centres. COPD was diagnosed in 77 patients (25.2%) by standard diagnostic spirometry. Using the copd-6 device, mean (SD) FEV1/FEV6 was 68 (8)% in patients with COPD and 78 (10)% in patients without COPD. Sensitivity and specificity at a FEV1/FEV6 cut-off of 73% were 79.2% and 80.3%, respectively. The area under the ROC curve was 0.84. Screening with the copd-6 device significantly predicted COPD. Gender, CCQ, and MRC were not found to predict COPD.
Conclusions: Using the copd-6 as a pre-screening device, the rate of COPD diagnoses by standard diagnostic spirometry increased from 25.2% to 79.2%. Although the sensitivity and specificity of the copd-6 could be improved, it might be an important device for prescreening of COPD in primary care and may reduce the number of unnecessary spirometric tests performed.
Trial registration: ClinicalTrials.gov NCT01013922.