[Guidelines for the prevention and management of bronchial asthma (2024 edition)].

Bronchial asthma (asthma) is a common chronic respiratory disease. Standardized diagnosis, treatment and effective clinical management are critical to improving asthma control, improving patients' quality of life, and reducing the disease burden. Based on the latest evidence-based research from both domestic and international references, the Asthma Group of the Chinese Thoracic Society has revised the " ()". This revision supplements the diagnostic pathway, and updates clinical staging, and severity grading of asthma. Furthermore, adjustments have been made in asthma evaluation, maintenance therapy, acute exacerbation management, severe asthma, atypical asthma, and treatment principles of asthma, according to the latest research evidence. The updated guideline serves as a comprehensive resource for healthcare professionals in China, providing the latest recommendations to improve their knowledge and competence in the standardized diagnosis and management of asthma.The key recommendations are listed below. Bronchial provocation test should be considered when forced expiratory volume in one second (FEV) is ≥70% predicted (excluding respiratory infections within the past 4 weeks) (1, D). When clinical symptoms suggest asthma but the bronchial provocation test is not available or does not meet the diagnostic criteria for variable airflow limitation, reliance on cutoff value alone to exclude asthma should be avoided. A presumptive diagnostic pathway may be initiated to improve the diagnostic accuracy (1, D). Diagnostic anti-inflammatory therapy may be initiated to confirm the diagnosis if any of the following criteria are met: (1) positive results (≥20% increase from baseline) in peak expiratory flow (PEF)-based bronchodilation test when spirometry is unavailable, excluding respiratory infections within the past 4 weeks; (2) FEV variability≥12% and absolute change ≥200 ml between two prior tests, excluding respiratory tract infections within the past 4 weeks; (3) small airway dysfunction [met 2 of 3 ≤65% predicated among the maximum instantaneous forced expiratory flow with 25% of the forced vital capacity (FVC) remaining to be exhaled (MEF25), MEF50, maximal mid-expiratory flow(MMEF)], or FEV improvement ≥ 10% with fractional exhaled nitric oxide (FeNO)≥35 ppb in bronchodilation test when baseline FEV ≥ 80% predicted (1, C). After biologic therapy or other anti-asthma therapy, patients who achieve≥ 1 year of symptom-free status, no exacerbation, normal/near-normal lung function, and no need for oral corticosteroids (OCS) may be considered to have achieved "clinical remission" (1, D). It would be better to classify asthma severity based on the treatment steps required to achieve asthma control rather than relying on the patient's pre-treatment (1, D). Type 2 airway inflammation characterized by elevated blood/sputum eosinophils, and/or FeNO, and/or atopy or elevated total immunoglobulin E (IgE) is predominant in severe asthma. Non-type 2 inflammation, defined as not meeting any of the above criteria, should be identified only after excluding confounders (e.g., infections and medications) (1, D). Patients should undergo psychosocial assessment (e.g., anxiety/depression scales) and evaluation for comorbidities if they suffered from dyspnea/chest tightness after routine therapy, and had normalized lung function, peripheral blood eosinophil, and FeNO simultaneously (1, D). Provocative dose that causes a 20% decrease in FEV in bronchial provocation test may reflect airway hyperresponsiveness and may be used in disease monitoring and therapeutic evaluation (2, D). Induced sputum eosinophil is one of the gold standard biomarkers for airway inflammation assessment, asthma phenotype classification, corticosteroid response prediction, and exacerbation risk assessment (1, A). Peripheral blood eosinophil ≥ 150/μl can be used to identify eosinophil phenotype or type 2 inflammatory endotype, as well as one of the key biomarkers to predict and evaluate biologic responses (1, C). Long-term treatment of inhaled corticosteroids (ICS) with the recommended clinical dose range is safe in asthma patients. However, prolonged high-dose ICS therapy may lead to systemic adverse effects, including osteoporosis, suppression of hypothalamic-pituitary-adrenal axis, and increased risk of pneumonia (1, D). For adults with severe asthma, low-dose OCS (≤7.5 mg/day prednisone equivalent) may be added as the last choice (1, D). ICS-long-acting β-agonists (LABA) demonstrate synergistic anti-inflammatory and anti-asthmatic effects, achieving efficacy equivalent to or better than doubling the ICS dose, and may improve patient's adherence and reduce the high-dose ICS-related adverse effects, and are particularly recommended for the long-term treatment of patients with moderate to severe asthma (1, A). Triple combination inhalers can be prescribed to improve symptoms, lung function, and reduce exacerbations when asthma remains uncontrolled on medium- or high-dose of ICS-LABA ( 1, A). Subcutaneous immunotherapy in adults with asthma may reduce required dosage of ICS and improve asthma-specific quality of life and lung function (2, B). For house dust mite (HDM)-sensitized adolescents or adults with FEV＞70% predicted, HDM sublingual immunotherapy may be added to reduce symptoms and ICS dose if symptoms persist despite low-to-medium-dose ICS-containing therapy (2, B). Step 1 treatment for asthma: As-needed low-dose ICS-formoterol is recommended for patients with limited to occasional transient daytime symptoms (<2 times/month, lasting hours), no nocturnal symptoms, no risk of exacerbations, and FEV>80% predicted (1, A). Step 2 treatment for asthma: As-needed low-dose ICS-formoterol is recommended, and significantly reduces moderate-to-severe exacerbations compared with short-acting β-agonist (SABA) monotherapy (1, A). Patients with persistent symptoms or exacerbations despite correct inhalation technique and adherence to Step 4 treatment should be referred to asthma specialists or specialized clinics for further evaluation (1, D). Follow-up visits should be scheduled every 2-4 weeks after initial therapy, then every 1-3 months if there is a response. Regular training of patients to in the correct use of inhaler techniques is essential for optimal asthma control (1, B). Risk factors associated with asthma-related death include: (1) a history of asthma that is requiring intubation and mechanical ventilation; (2) hospitalization or emergency care visit for asthma exacerbation in the past year; (3) currently use or recent cessation of OCS; (4) no current ICS use; (5) overuse of SABA, especially more than 1 canister of salbutamol (or equivalent) per month; (6) psychiatric illness or psychosocial problems, including sedative use; (7) poor adherence; (8) confirmed food allergy history; (9) comorbidities including pneumonia, diabetes, and arrhythmias (1, D). In the early stages of mild to moderate asthma exacerbations, when budesonide-formoterol combination therapy is used as an anti-inflammatory reliever, 1-2 additional inhalations of budesonide-formoterol (160/4.5 μg strength) may be taken. However, the daily dose should not exceed 8 inhalations (1, D). Severe asthma is uncontrolled asthma despite prescribing 3 or more months of continuous standardized use of a medium- or high-dose ICS-LABA and has been treated for comorbidity diseases and avoid environmental stimulus, or worsening after stepping down to a lower dose ICS-LABA (1, D). Patients with severe type 2 asthma can be treated with biologic therapy, those who had a good response to type 2-targeted biologic therapies can prioritize decrease or stop maintenance OCS therapy, but should not completely stop maintenance therapy with ICS-LABA (1, A). Adult patients with persistent symptomatic asthma despite step 5 treatment, add-on low-dose azithromycin therapy, such as azithromycin 250 to 500 mg/day, three times a week, for 26-48 weeks, may be prescribed to reduce exacerbations (2, A). Bronchial thermoplasty is indicated for adult patients whose asthma remains uncontrolled despite optimized asthma treatment and referral to a specialist severe asthma center, or for whom targeted biological therapy is not available or appropriate (2, A). The treatment principles for cough variant asthma (CVA) are the same as those of typical asthma, and most patients respond to ICS or ICS-LABA. ICS-LABA is recommended as the first choice and should be used for more than 8 weeks (1, B). There are different phenotypes and treatment responses in CVA. For CVA patients with poor therapeutic response and severe airway inflammation, the addition of leukotriene receptor antagonist therapy or short-term use of OCS (10-20 mg/d, 3-5 d) may be considered (2, D). In asthma associated with fungal sensitization, antifungal drugs can reduce airway inflammation and reduce the dose of systemic corticosteroids by minimizing fungal colonization and burden (1, D). In asthma associated with fungal sensitization, anti-IgE, anti-interleukin (IL)-5, anti-IL-5Rα, anti-IL-4Rα monoclonal antibodies, and other targeted biologic therapies can reduce exacerbations, improve asthma control and lung function, and improve quality of life. However, large-scale trials are needed to further investigate their efficacy and safety (1, B). The most effective way to prevent aspirin-induced asthma (AIA) is to avoid reapplication of this drug, and desensitization therapy may be considered in AIA patients who require high-dose ICS to control asthma symptoms, or who have failed to improve nasal inflammation and polyposis with conventional treatment, or who require aspirin for other diseases (2, B). Severe asthma with chronic rhinosinusitis with nasal polyps may benefit from anti-IgE monoclonal antibodies, anti-IL-5 monoclonal antibodies, anti-IL-5Rα monoclonal antibodies, and anti-IL-4Rα monoclonal antibodies (1, B). Patients with a diagnosis of asthma should be considered for the diagnosis of asthma-COPD overlap (ACO) if they have persistent airflow limitation (FEV/FVC<70% after bronchodilator inhalation), a history of exposure to noxious gases or substances (smoking or previous history of smoking≥10 pack-years), emphysema as assessed by high-resolution computerized tomography, and decreased diffusion capacity after 3 to 6 months of standardized treatment (1, D). When developing control goals for asthma with patients, the health care system, availability of medications, cultural differences, and personal preferences should be considered (1, D).