This study aims to test a diagnostic algorithm for obstructive airways diseases that may be used in daily practice to obtain a correct differential diagnosis and, hence, initiate an adequate therapy according to the current guidelines. The proposed algorithm will be used to categorize patients in 4 different diagnoses with specific treatment choices: asthma, obstructive asthma, overlap asthma with COPD, and COPD. The study will evaluate which tests and criteria contribute most to the diagnostic work-up and final diagnosis.
Test battery for diagnosis
* spirometry with bronchodilator reversibility testing
* bodyplethysmography: spirometry, volumes, resistance, diffusing capacity
* exhaled NO
* blood sample
* CT scan of thorax (only when obstructive spirometry)
* histamine challenge (only when spirometry is not obstructive)
* induced sputum (not for protocol interpretation)
Definition of endpoints
1. Physician based diagnosis:
diagnosis based on clinical exam and spirometry
2. Algorithm based diagnosis:
diagnosis based on clinical exam and test battery
3. Final standard diagnosis diagnosis based on clinical exam, test battery and clinical evolution of 1 year.
