Effect of systemic inflammation and multi-morbidity on outcome of adult-onset asthma

Abstract

Aims and objectives: Effect of systemic inflammation and comorbidities on treatment and outcome of adult-onset asthma remains unknown and is the objective of this study. Methods: As part of Seinajoki Adult Asthma Study (SAAS) with 12-year follow-up of patients with new-onset adult asthma, serum interleukin-6 (IL-6), high-sensitivity C-reactive protein (hsCRP) and lung function were measured and clinical information on comorbidities and medication collected. After excluding patients with co-existing COPD 170 patients remained in the cohort. Results: At follow-up visit, 54 % of the patients had systemic inflammation as indicated by elevated IL-6 or hsCRP, 58 % had at least one comorbidity and 30 % at least two comorbidities (other than asthma-related). Patients with systemic inflammation were treated with higher dose of inhaled corticosteroid (ICS) and they had lower lung function and higher blood neutrophils when compared to patients without systemic inflammation. Patients having ≥ 2 comorbidities had lower asthma control test (ACT) score and this association remained significant when adjusted for age, BMI, gender and pack-years. Patients with both systemic inflammation and comorbidities showed poorest outcome of asthma. In multivariate regression analysis, high ICS dose was predicted by elevated IL-6 (>1.55 pg/ml), elevated blood neutrophils (>3.9x10 9 /l) and eosinophils (>0.2x10 9 /l) at follow-up and poorer lung function at baseline (FEV 1 1 /FVC post Conclusions: Altogether, in patients with adult-onset asthma, elevated IL-6 was associated with use of high dose ICS while multi-morbidity was linked to worse symptoms of asthma.