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New evidence of bronchodilation tests in asthma diagnosis and treatment

Published online: August 1, 2021

Bronchial asthma (asthma) is one of the most common respiratory diseases. Many patients with asthma, especially mild asthma, are undiagnosed and untreated because of mild symptoms, near-normal spirometry, and the severity underestimated by patients and physicians. Global Initiative for Asthma recommend the diagnosis of asthma should be based on variable respiratory symptoms and variable expiratory airflow limitation. However, bronchodilation tests (BDT) are more appropriate for patients with forced expiratory volume in 1 second (FEV1) <70%, and near-normal spirometry may be a cause of the low diagnostic sensitivity of the BDT. The uncontrolled symptoms, acute attacks and deaths caused by undiagnosed asthma impose a huge medical burden on society. Therefore, how to improve the identification of mild asthma has become an urgent problem in the prevention and treatment of asthma.

In a recent article in The Journal of Allergy and Clinical Immunology: In Practice, Hao et al report the results of an open-label, prospective cohort study to determine whether airway reversibility in BDT combined with fractional exhaled nitric oxide (FeNO) can predict the response to anti-asthma therapy in suspected asthma patients. They conducted a two-phase study. In phase I, they included patients with chronic recurrent asthma symptoms, normal forced expiratory volume in 1 second (FEV1), but negative BDT results. Inhaled corticosteroids and long-acting β agonists were given to the patients for 4 weeks to observe the response to the treatment, and finally they established a predictive model to predict the response to anti-asthma therapy. In phase II, they collected lung tissues from patients who underwent pneumectomy for lung nodules. Inflammatory cells and cytokines were analyzed in the 2 groups following the predictive model.

The study showed that patients in the positive response to anti-asthma therapy group had a higher baseline FeNO and greater absolute (∆) and percent (∆%) improvements in forced vital capacity, FEV1, and forced expiratory flows (FEFs) in the baseline BDT test than those who did not have a positive response to anti-asthma therapy. A joint model of FeNO and ∆FEV1% was established. Inflammatory cytokines were higher in the lung tissues of patients with predicted positive response to anti-asthma therapy than in those with predicted negative response to anti-asthma therapy. In conclusion, ∆FEV1% in BDT together with FeNO predicted a positive response to asthma therapy in patients with normal FEV1 and negative BDT at baseline. Evidence of pathological changes increased the credibility of the predictive model.

Early diagnosis and treatment are important for asthma, especially mild asthma. The increases in spirometric indices in BDT combined with FeNO to predict the response to anti-asthmatic therapy is an effective method to improve the diagnosis of mild asthma and mitigate the decrease in general health, vitality, and mental health caused by undiagnosed asthma. The predictive model supports physicians in accurately identifying patients with asthma, confidently administering trials of anti-asthma treatments, and reducing the unnecessary use of glucocorticoids. In primary hospitals or institutions, if asthma is suspected, conducting BDT and FeNO can guide decisions on which patients should receive diagnostic trials of anti-asthma therapy.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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