Systematic Approach for the Diagnosis and Treatment of Obstructive Lung Diseases

The differential diagnosis of asthma and COPD is sometimes difficult. Recently, an overlap syndrome has been defined based on the concurrence of asthma and COPD characteristics. These characteristics are based on expert opinions and have never been investigated nor validated prospectively. The investigators assume that the management strategy, the symptom burden and disease progression will differ between asthma, COPD and ACOS. Therefore, the study wants to establish baseline criteria for an appropriate disease definition and evaluate the potential impact on treatment and symptom control.

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.