Parameters associated with persistent airflow obstruction in chronic severe asthma

Abstract

The significance of severe airflow obstruction in severe asthma is unclear. The current study determined whether severe airflow obstruction is related to inflammatory or structural changes in the airways.Patients with severe asthma from a tertiary referral clinic were divided into two groups according to their postbronchodilator forced expiratory volume in one second (FEV1): severe persistent airflow limitation (FEV1v50% predicted; group S; n=37) and no obstruction (FEV1w80% pred; group N; n=29). Smoking history, atopic status, lung function tests, exhaled NO, blood eosinophil count, quality of life scores using St George9s Respiratory Questionnaire and high resolution computed tomography (HRCT) of the lungs were assessed.Patients from group S were older and had longer disease duration. There was no difference in smoking history, atopic status, hospital admissions, quality of life scores and amount of treatment with inhaled or oral corticosteroids. Exhaled NO and peripheral blood eosinophils were higher in group S (21.0¡2.4 versus 12.8¡2. , respectively). HRCT scores for bronchial wall thickening and dilatation were higher in group S with no differences in air trapping. Peripheral blood eosinophilia and bronchial wall thickening on HRCT scan were the only parameters significantly and independently associated with persistent airflow obstruction.Patients with severe asthma and irreversible airflow obstruction had longer disease duration, a greater inflammatory process and more high resolution computed tomography airway abnormalities suggestive of airway remodelling, despite being on similar treatments and experiencing equivalent impairment in quality of life.

International ERS/ATS guidelines on definition, evaluation and treatment of severe asthma

“…Finally, severe airway obstruction is a characteristic in some phenotypes of severe asthma, with studies suggesting that eosinophilic and/or neutrophilic inflammation may contribute to greater airflow limitation [116,123,124]. One of the SARP clusters was characterised by severe airway obstruction, with continued b-agonist reversibility, but without reversibility into the normal range, and in association with sputum neutrophilia [15].…”

“…Severe asthmatics are often referred to as corticosteroiddependent, refractory or corticosteroid-insensitive asthmatics. In 30% of severe adult asthma patients, oral corticosteroids (OCS) are required in addition to ICS to maintain some degree of asthma control [23,120,124,141]. Intramuscular injections of triamcinolone as a maximal dose of corticosteroid therapy can improve asthma control, reduce sputum eosinophils and increase FEV1 [164,165], supporting the presence of relative insensitivity to this treatment, rather than a complete resistance.…”

“…Approximately one-third of the current SARP cohort were on regular OCS, with over half needing more than three bursts of OCSs in the previous year [21,120,124,141]. The optimal timing for initiation of OCS therapy has also not been defined.…”

“…Short-and long-acting b-adrenergic bronchodilators Many adult and paediatric patients with severe asthma have persistent chronic airflow obstruction despite treatment with ICS and short-and/or long-acting bronchodilators [23,124].…”

Inhaled corticosteroids as combination therapy with β-adrenergic agonists in airways disease: present and future

“…Approximately 5-10% of patients with asthma fall in the category of those suffering from severe asthma; in these patients, despite the use of maximum ICS dose, and sometimes combined with regular oral corticosteroids, their asthma remains uncontrolled with continuing asthma symptoms, exacerbations of asthma and persistent airflow obstruction [75][76][77]. Many of these patients are labelled as corticosteroid-dependent, in that reduction in either maintenance ICS or oral CS leads to a deterioration of asthma control.…”