Assess Accuracy of Primary Care Asthma and COPD Diagnosis Using Oscillometry and FeNO vs Specialist Diagnosis

Diagnosis of asthma and chronic obstructive pulmonary disease (COPD) currently relies heavily on pulmonary function tests (PFTs), with spirometry as the core method. However, the effectiveness of spirometry is closely linked to patients' ability to perform maximal, forceful breathing maneuvers. This poses difficulties for individuals with varying physical capacities, leading to challenges in test use, result interpretation, and reproducibility. Such limitations often require skilled specialists, which may not be available in all settings, especially in primary care.

Primary care providers are the initial interface for patients with respiratory symptoms, tasked with rapidly evaluating and diagnosing conditions during brief patient interactions. Early diagnosis of asthma and COPD is crucial, yet spirometry standards-such as those set by the European Respiratory Society and American Thoracic Society-often cannot be met in primary care due to resource and expertise constraints. Operational barriers, including equipment costs, maintenance, staff training, and integration into routine practice, further hinder widespread adoption of spirometry.

Adding to the complexity, variable bronchodilator responsiveness complicates the differential diagnosis of obstructive airway diseases. Traditional reversibility criteria based on FEV1 changes following bronchodilator administration may be unreliable, reducing their diagnostic utility for distinguishing asthma from COPD and highlighting the need for multidimensional approaches.

Oscillometry is emerging as a promising alternative or adjunct to spirometry. It is a non-invasive method capable of detecting airway resistance and reactance, which can reveal early functional changes in asthma and COPD-even before clinical symptoms appear. Oscillometry is valuable for monitoring disease progression, assessing bronchodilator response, and may be more sensitive for small airway dysfunction, especially in patients with normal or slightly impaired lung function.

Measurement of fractional exhaled nitric oxide (FeNO) is another innovative technique. As a marker for T-helper 2 cell-mediated airway inflammation, FeNO can enhance the diagnosis and monitoring of asthma. Guidelines recommend FeNO thresholds for diagnosis and management, adding an objective layer to clinical decision-making. International guidelines advise integrating FeNO and additional objective tests, such as eosinophil counts, with standard PFTs to support asthma diagnosis.

Addressing the considerable unmet need for earlier identification of asthma and COPD, a multicenter, multinational, cross-sectional study has been designed to evaluate the technical feasibility and diagnostic accuracy of oscillometry and FeNO testing in primary care. Conducted across six countries in the Middle East and Africa, Asia, and Latin America, the study will systematically compare primary care-based diagnosis using combined oscillometry and FeNO testing with conventional specialist-led diagnostics.

Patients with suspected asthma or COPD will be enrolled from outpatient departments during a six-month recruitment period. Participating primary care physicians will be trained according to Global Initiative for Asthma (GINA) and Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines, and equipped with tools such as the Ambulatory Lung Diagnosis System. Recruitment will avoid sites biased toward severe cases, ensuring a representative patient population. Provisional diagnoses will be established via history, symptom questionnaires, and results of oscillometry and FeNO testing; where immediate specialist assessment is not feasible, patients will return within three days for further evaluation. No follow-up visits are planned. The study aims to inform clinical practice by clarifying the feasibility and effectiveness of integrating these innovative diagnostic methods into primary care, with the goal of facilitating earlier and more reliable identification of asthma and COPD.

Inclusion criteria

Patients are eligible to be included in the study if all the following criteria apply and after providing written informed consent:

Suspected asthma (asthma group)

• Patients ≥ 18 years old or with legal age of consent in the jurisdiction in which the study is taking place, at the time of signing the ICF.
• Patients presenting with symptoms of wheezing, cough, chest tightness, shortness of breath, but without a clinically confirmed diagnosis of asthma.

Suspected COPD (COPD group)

• Patients ≥ 40 years old at the time of signing the ICF.
• Patients presenting with symptoms of dyspnea, chronic cough or sputum production, but without a clinically confirmed diagnosis of COPD.

Exclusion criteria

Patients are excluded from the study if any of the following criteria apply:

• Prior diagnosis of COPD or asthma.
• Use of ICS in the last 6 months or use of oral corticosteroids in the last 3 months.
• Any diseases that influence lung function result such as lung cancer, pneumonia, active pulmonary tuberculosis, pulmonary embolism, and interstitial lung disease.
• Any history of recent surgery that affects lung function results, including but not limited to thoracotomy surgery, pneumothorax surgery, and thoracic drainage.
• Contraindication to spirometry or oscillometry test, or allergy to bronchodilator.
• Currently pregnant or breast-feeding women.
• If the investigator judges that the patient is unlikely to comply with study procedures, restrictions, and requirements.