Office spirometry was performed by GPs using a portable multifunction spirometer (Spirobank Office; MIR; Rome, Italy). Each of these spirometers is calibrated before being sold and does not need further regular calibration unless major damage occurs. GPs were previously trained on spirometry by reference specialists using the same type of device. No technical or interpretation problems were reported by specialists. Spirometry supplies were given free.
The parameters registered, absolute values and percentage of predicted, were as follows: FVC, FEV1, percentage of predicted FEV1, peak expiratory flow (PEF), and forced expiratory flow at 25 to 75% of FVC. Predicted values were those approved by the European Respiratory Society. Spirometry was considered normal for FEV1/FVC ratio > 0.7 and FVC > 80% of predicted. Patterns of abnormality were defined as follows: airway obstruction (FEV1/FVC ratio < 0.7; FVC > 80% of predicted), mixed (FEV1/FVC ratio < 0.7;, FVC < 80% of predicted), and restrictive pattern (FEV1/FVC > 0.7; FVC < 80% of predicted).
The Spirobank Office spirometer has a quality check for reliability and reproducibility of spirometric curves (according to American Thoracic Society criteria), allowing to accept or refuse a test, and provided an automated interpretation of spirometry. The Spirobank Office spirometer adopts the following reproducibility criteria: PEF reproducible if APEF is < 10%; FVC reproducible if AFVC is < 5% or < 200 mL; and FEV1 reproducible if AFEV1 is < 5% or < 100 mL. After the second test, a “—” sign on the display means “not reproducible” and a “ + ”sign means that the test is reproducible.
Reversibility tests with bronchodilators or corticosteroids were fully described in the educational sessions, but it was not obligatory for GPs to perform these tests themselves. They could, if preferred, refer the patient to the specialist for the test. There was no direct control of spirometry by GPs by the reference specialists.