Non-invasive tools beyond lung function before and after specific inhalation challenges for diagnosing occupational...

Area of Science:

• Allergy and Immunology
• Occupational Medicine
• Pulmonology

Background:

• Occupational asthma (OA) diagnosis relies on identifying airway inflammation and hyperresponsiveness post-allergen exposure.
• Specific inhalation challenges (SIC) with occupational allergens are used to elicit responses.
• Comparative diagnostic accuracy of non-invasive markers like FeNO, sputum eosinophils, and methacholine responsiveness after SIC is not well-established.

Purpose of the Study:

• To assess the diagnostic accuracy of fractional exhaled nitric oxide (FeNO), sputum eosinophils, and methacholine responsiveness after specific inhalation challenges (SIC) for diagnosing occupational asthma (OA).

Main Methods:

• 122 subjects with work-related shortness of breath were enrolled.
• The 'gold standard' for diagnosis combined airway obstruction (pulmonary responders) and/or an increase in FeNO (≥13 ppb) post-SIC.
• Diagnostic performance of FeNO, sputum eosinophils, and bronchial hyperresponsiveness was compared against this 'gold standard' and pulmonary responder status alone.

Main Results:

• When FeNO increase and pulmonary response defined the 'gold standard', sputum eosinophils and/or bronchial hyperresponsiveness showed high false-positive rates.
• Using pulmonary response alone as the 'gold standard', FeNO increase demonstrated higher diagnostic accuracy (sensitivity 0.57, specificity 0.82) compared to sputum eosinophils (0.52/0.75) and bronchial hyperresponsiveness (0.43/0.87).
• Individual cases suggested potential, but likely false-positive, detection of OA by sputum eosinophils or bronchial hyperresponsiveness alone.

Conclusions:

• Combining lung function (pulmonary response) and FeNO increase is recommended as the primary method for assessing SIC effects in OA diagnosis.
• Changes in sputum eosinophils and bronchial hyperresponsiveness after SIC have limited additional diagnostic value but may be useful in specific clinical scenarios.