Risk Factors of Severe Adult-onset Asthma: A Multi-factor Approach

Abstract

\n Background: The aim was to identify risk factors of severe adult-onset asthma.Methods: We used data from 1350 population-based asthmatics (Adult Asthma in Finland) with adult-onset asthma (age range 31-93 years) from Finnish national registers. Severe asthma was defined as self-reported severe asthma AND asthma symptoms causing much harm AND regular impairment AND (≥1 oral corticosteroid course/year OR regular oral corticosteroids OR wake up in the night due to asthma symptoms/wheezing attach ≥ a few times/month). Sixteen covariates covering several domains (personal characteristics, education, life-style, early life factors, asthma characteristics and multimorbidities) were selected based on literature and were studied in association with severe asthma using logistic regressions. Results: The study population included 100 (7.4 %) individuals with severe asthma. In a univariate analysis, severe asthma was associated with male sex, age, low education, no professional training, ever smoking, ≥ 2 siblings, ≥ 1 chronic comorbidity and Non-steroidal anti-inflammatory drug (NSAID) -exacerbated respiratory disease (NERD) (p<0.05); and trends for association (p<0.2) were observed for severe childhood infection, presence of chronic rhinosinusitis with nasal polyps, and being the 1st child. The 10 variables (being 1st child was removed due to multicolinearity) were thus entered in a multivariate regression model and severe asthma was significantly associated with male sex (OR [CI95%] = 1.96 [1.16-3.30]), ever smoking (1.98 [1.11-3.52]), chronic comorbidities (2.68 [1.35-5.31]), NERD (3.29 [1.75-6.19]), and ≥ 2 siblings (2.51 [1.17-5.41]). There was a dose-response effect of the total sum of these five factors on severe asthma (OR [CI95%] = 2.30 [1.81-2.93] for each increase of one unit of the score). Conclusions: Male sex, smoking, NERD, comorbidity, age and number of siblings were independent risk factors for self-reported severe asthma. The effects of these factors seem to be additive; each additional risk factor gradually increase with the risk of severe asthma.