Office spirometry significantly improves early detection of COPD in general practice: the DIDASCO Study.

STUDY OBJECTIVES To determine if spirometry is essential for the early detection of COPD in general practice, compared to the screening value of a short questionnaire. METHODS A prospective survey of the population aged 35 to 70 years visiting their general practitioner (GP) during a 12-week period, using a questionnaire on symptoms of obstructive lung disease (OLD). Spirometry was performed in all participants with positive answers and in a 10% random sample from the group without complaints. Twenty GPs were provided with a hand-held spirometer, and received training in performance and interpretation of lung function tests. All 35- to 70-year-old patients (n = 3,408) were screened for current use of bronchodilators. The subgroup receiving bronchodilators (n = 250, 7%) was assumed to have OLD, and was excluded. Airflow obstruction was defined according to the European Respiratory Society standards. RESULTS The positive predictive power of the questionnaire was low (sensitivity, 58%; specificity, 78%; likelihood ratio, 2.6). One hundred twenty-six cases of formerly unknown OLD were detected in the group of patients with complaints, vs an extrapolated number of 90 in the group without complaints. Despite a negative predictive value of 95% for the questionnaire used, 42% of the newly diagnosed cases of OLD would not have been detected without spirometry. CONCLUSIONS The use of a spirometer is mandatory if early stages of OLD are to be detected in general practice. Screening for airflow obstruction almost doubles the number of known patients with OLD.