The objective of this observational study is to assess the relevance of inflammometry (based on the measurement of fractional exhaled nitric oxide (FeNO) and blood eosinophil count (BEC)) as a tool for prioritizing respiratory diagnostic tests.

The study will evaluate the role of inflammometry (FeNO and BEC) in prioritizing diagnostic respiratory tests. It will include patients aged six and older with suspected asthma, referred by non-pulmonologists for diagnostic asthma testing (spirometry or methacholine challenge test) at three hospital centers: Sherbrooke University Hospital Center (CHUS), Sainte-Justine University Hospital Center (CHU Sainte-Justine), and the Montreal Children's Hospital.

The hypothesis is that using inflammometry as a prioritization tool would reduce diagnostic delays for high-risk patients with elevated biomarkers. This study could help shorten wait times, relieve congestion in diagnostic testing queues, and improve the diagnostic pathway. Additionally, it would enhance the interpretation of pulmonary function test results by incorporating inflammometry findings, leading to better patient stratification.

Patients referred from primary care will undergo pulmonary function testing (spirometry ± methacholine challenge) and, as part of the study:

FeNO measurement using a portable device Blood test for eosinophil count Questionnaire on asthma control and quality of life, completed at the visit and at follow-ups at 4, 8, and 12 months

BACKROUND : Asthma is one of the most prevalent chronic diseases worldwide. In Canada, it affects 11% of the population. In Quebec, an estimated 900,000 people suffer from asthma, including 300,000 children. Type 2 eosinophilic inflammation is present in 50% of asthma cases and in 95% of individuals with severe disease, who consume more healthcare resources. This type of inflammation is clinically identified through non-invasive measurements of exhaled nitric oxide (FeNO) and blood eosinophil count (BEC).

Asthmatic patients with Type 2 inflammation are at higher risk of asthma attacks and appear to be at risk of accelerated lung function decline, both in adults and children. The presence of Type 2 inflammation predicts a strong response to inhaled corticosteroids (ICS).

Currently, post-bronchodilator reversibility and/or bronchial hyperresponsiveness documented via spirometry are the two main approved methods for diagnosing asthma. Bronchial provocation testing is required in 80% of suspected asthma cases, but our population faces a severe lack of access to this test.The average wait time for this 1-2 hour procedure exceeds one year in our three centers.

Currently, prioritization is based on the order in which requests are received, with internal referrals given priority over external ones. In Europe, FeNO is already used as a complementary diagnostic tool in primary care, while in Quebec, it is only accessible in severe asthma clinics.

Type 2 eosinophilic inflammation is present in 50% of asthma cases and in 95% of severe asthma cases. This inflammation can be identified through non-invasive biomarkers, such as FeNO and blood eosinophil count. Individuals with type 2 inflammation are at higher risk for asthma attacks and are more likely to experience accelerated decline in respiratory function, both in adults and children. However, type 2 inflammation also predicts a strong response to inhaled corticosteroids (ICS).The identification of these markers represents a treatable trait.

HYPOTHESIS

As a prognostic procedure that identifies a treatable trait, early measurement of inflammatory biomarkers could:

1. Prioritize highly inflamed patients for bronchial provocation testing.
2. Provide personalized therapy based on the inflammation type, with evidence-based recommendations included in the medical reports.
3. Improve the management of asthmatic patients who do not respond to initial treatment, ensuring better access to specialized care.

OBJECTIVES

For patients ≥6 years old with suspected asthma, referred by non-pulmonologists for diagnostic testing, the study aims to use inflammometry to:

1. Reduce diagnostic delays for high-risk patients with probable asthma and exacerbation risk.
2. Enhance test result interpretation by incorporating inflammometry findings, asthma probability assessment, exacerbation risk, and expected response to anti-inflammatory therapies.
3. Alleviate waiting lists across our three centers.
4. Analyze and optimize the diagnostic pathway for suspected asthma cases in Quebec by generating real-world evidence on the clinical, economic, and environmental benefits of inflammometry.

METHODOLOGY For one year, an additional respiratory therapist at each center will conduct diagnostic tests for suspected asthma (spirometry with pre/post-bronchodilator testing or methacholine challenge) requested by non-pulmonologists at the Sherbrooke University Hospital Center (CHUS), CHU Sainte-Justine, and the Montreal Children's Hospital.

All patients ≥6 years old on the waiting list will be invited to a clinic visit, where a complementary assessment will be offered. This innovative approach includes:

1. FeNO measurement (exhaled air)
2. Blood eosinophil count (capillary or venous sample)
3. Questionnaires on asthma control and quality of life, completed at baseline and at 4, 8, and 12 months

If spirometry is non-diagnostic, bronchial provocation will be prioritized based on inflammatory profile:

1. if ≥1 biomarker is elevated (for those ≥12 years old, FeNO ≥25 ppb or blood eosinophils ≥300 cells/µL; for those aged 6-<12 years, FeNO ≥20 ppb or eosinophils ≥300 cells/µL), the bronchial provocation test will be prioritized (<2-4 weeks).
2. If both biomarkers are low, the scheduling of the provocation test will follow the usual timelines.

If spirometry or provocation confirms asthma, additional biomarker data will inform the physician about the risk of asthma attacks.

OUTCOMES The primary outcome will be diagnostic delay evolution for high- vs. low-risk asthma patients, analyzed before, during, and after the project.

Receiver Operating Characteristic (ROC) curves will be used to assess the diagnostic performance of inflammometry as a potential diagnostic tool, including determining thresholds that could eliminate the need for provocation test. The analyses will be completed by questionnaires evaluating user satisfaction, economic efficiency measures (cost-effectiveness, cost-utility, budget impact), and an environmental impact assessment (measured in kgCO2 emitted by inhalers used when asthma is not diagnosed).

IMPACT

1/ Implementation of an evidence-based prioritization system for primary care referrals, substituting the current chronological approach, to reduce wait times for high-risk patients. 2/ Integrating biomarker results with pulmonary function test outcomes will refine their interpretation and better assess the likelihood of an asthma diagnosis, exacerbation risk, and response to anti-inflammatory treatments. 3/The resources allocated by this project will help reduce waitlists. 4/ Real-world evidence from Quebec will be used to improve the asthma diagnostic algorithm, facilitating the integration of inflammometry into asthma diagnosis in the province. This could potentially eliminate 20% of bronchial provocation tests, reducing costs with net-zero financial impact.

Inclusion Criteria:

• patients age 6 and older
• referred by primary care ofr an asthma diagnostic test (spirometry or methacholine challenge)

Exclusion Criteria:

• referred by pulmonologist

People with asthma-suggestive symptoms, referred to Sherbrooke Universty Hospital Center (CHU), CHU Sainte-Justine, and the Montreal Children's Hospital by a non-pulmonologist healthcare professional for asthma diagnosis (pre/post-bronchodilator spirometry and, if non-diagnostic, a methacholine bronchial provocation), will be scheduled for an appointment with the project's designated respiratory therapist .

Data of this study may be shared if the investigators proposed use of the data has been approved by the study principal investigator and an institutional research ethics committee.

up to 2035

Data of this study may be shared if the investigators proposed use of the data has been approved by the study principal investigator and an institutional research ethics committee.