severe cases of ACO. These monoclonal antibodies include omalizumab (an Anti-IgE antibody), mepolizumab (an anti-IL-5 antibody) and benralizumab (an anti-IL-5 receptor α antibody). People with ACOS and eosinophilia have a better response to ICS; with fewer exacerbations and hospitalizations seen in ACOS treated with long term ICS. Systemic corticosteroids (intravenous or oral steroids) may be used during exacerbations of ACOS. Prognosis The progression of permanent airflow obstruction (as measured by the rate of FEV1 decline) is slower in ACO as compared to COPD, but ACO with late onset asthma is associated with a more rapid FEV1 decline (a more rapid progression of obstruction) and a worse prognosis. ACO with late onset asthma is associated with a higher mortality as compared to COPD, asthma or healthy controls. Excluding ACO with late onset asthma, ACO has better survival (lower mortality) than COPD, but higher mortality compared to asthma. In other studies, ACO was associated with worse dyspnea symptoms, more coughing, wheezing, sputum production as well as more frequent and more severe exacerbations as compared to COPD or asthma. Epidemiology Due to heterogeneity of diagnostic criteria and a paucity of clinical trials, the prevalence of ACO is not well known. Based on a meta analysis, the prevalence of ACO in the general population is estimated to be 2%, whereas the prevalence of ACO in those with asthma is 26.5% and in those with COPD it is 29.6%. References