Quality of spirometry in primary care for case finding of airway obstruction in smokers

Background: Diagnosis of chronic obstructive pulmonary disease (COPD) and its severity determination is based on spirometry. The quality of spirometry is crucial.

Objectives: Our aim was to assess the quality of spirometry performed using a spirometer with automated feedback and quality control in a general practice setting in Switzerland and to determine the prevalence of airflow limitation in smokers aged > or =40 years.

Method: Current smokers > or =40 years of age were consecutively recruited for spirometry testing by general practitioners. General practitioners received spirometry training and were provided with an EasyOne spirometer. Spirometry tests were assigned a quality grade from A to D and F, based on the criteria of the National Lung Health Education Program. Only spirometry tests graded A-C (reproducible measurements) were included in the analysis of airflow limitation.

Results: A total of 29,817 spirometries were analyzed. Quality grades A-D and F were assigned to 33.9, 7.1, 19.4, 27.8 and 11.8% of spirometries, respectively. 95% required < or =5 trials to achieve spirometries assigned grade A. The prevalence of mild, moderate, severe and very severe airway obstruction in individuals with spirometries graded A-C was 6, 15, 5 and 1%, respectively.

Conclusion: Spirometries in general practice are of acceptable quality with reproducible spirometry in 60% of measurements. Airway obstruction was found in 27% of current smokers aged > or =40 years. Office spirometry provides a simple and quick means of detecting airflow limitation, allowing earlier diagnosis and intervention in many patients with early COPD.