Risk factors for severe exacerbations in a real-life population of adults with severe refractory asthma

Abstract

Background: Exacerbations are an important cause of morbidity in asthma, particularly in severe disease. Previous studies have identified variables associated with exacerbations, although little is known about risk factors in real-life populations of severe asthma. Methods: We determined the influence of demographics, disease characteristics and biomarkers of inflammation on the frequency of severe exacerbations in 872 adults with refractory asthma recruited to the British Thoracic Society Severe Asthma Registry. Results: 717 (82%) of subjects gave a history of ≥2 severe exacerbations in the last year and almost two-thirds had ≥4. Frequent exacerbations were significantly associated with younger age, higher BMI, higher ACQ score, worse asthma quality-of-life score, higher anxiety and depression score, history of GORD, increased unscheduled GP/emergency visits and hospital admissions in the last year and higher exhaled nitric oxide (FeNO). Preliminary analyses revealed independent variables associated with an increased risk of exacerbations were ACQ score, unscheduled GP/emergency visits in the last year, number of hospital admissions in the last year and FeNO in the total population and blood eosinophils in those not on maintenance oral steroids. Conclusion: Over 80% of a real-life population of adults with severe refractory asthma gave a history of frequent (≥2) severe exacerbations in the last year. Clinical outcomes and inflammatory variables were independent risk factors for severe exacerbations in this population. Further analysis will examine whether combining the independent risk factors in a scoring system can identify those at greatest risk of severe exacerbations.