Abstract
Introduction: Asthma patients with persistent airflow obstruction (PAO) have not been well-characterised. We compared patients with and without PAO in a cohort of non-smoking asthma patients.
Methods: Clinician-diagnosed asthma patients seen at our hospital's respiratory clinic from 1 Jan 2015 to 31 Dec 2015 were prospectively recruited. Participating patients completed a questionnaire about asthma history. Electronic records were assessed to obtain additional information about exacerbation history, spirometry and blood results. Inclusion criteria were never-smokers, and available pre and post-bronchodilator spirometry. PAO was defined as post-bronchodilator FEV1<80% predicted and post-bronchodilator FEV1/FVC<70%. Continuous variables are expressed as median (IQR) and categorical variables as number (percentage).
Results: Of the 552 asthma patients seen in clinic, 439 patients (79.5%) consented to the study, and 212 patients fulfilled the inclusion criteria. Sixty-one patients had PAO. Patients with PAO were older (60 (53-70)yrs vs 52 (28-64)yrs, p<0.001), had longer duration of asthma (22 (11-37)yrs vs 11 (3-25)yrs, p=0.008), had higher absolute blood neutrophils (6.9 (4.1-9.7)cells/uL vs 5.3 (3.8-7.1)cells/uL, p=0.017), had greater bronchodilator response (BDR) (9 (3-19)% vs 4 (1-11)%, p=0.006), and more likely to have history of near fatal asthma. After multivariate analysis, age, BDR and blood neutrophils were independent variables associated with PAO. Asthma control test scores and exacerbation rates were similar between both groups.
Conclusions: Demographic and inflammatory profiles differ between patients with and without PAO. Longitudinal studies are needed to determine long term prognosis in these 2 groups.
- Copyright ©the authors 2016
