Clinical burden and predictors of asthma exacerbations in patients on guideline-based steps 4-6 asthma therapy in the TENOR cohort

Background: Patients with severe or difficult-to-treat asthma on guideline-recommended Steps 4/5/6 therapy have not previously been described. Objective: To characterize patients with severe or difficult-to-treat asthma on Steps 4/5/6 therapy and assess predictors of future asthma exacerbations. Methods: Patients ages ≥12 years with baseline and month 12 medication data were assigned to Steps 4/5/6 care levels from the 2007 National Heart, Lung, and Blood Institute guidelines. Demographic, atopic, and clinical characteristics at baseline and month 12 were assessed by using descriptive statistics. Asthma-related quality of life was assessed by using the Mini Asthma Quality of Life Questionnaire, and work and activity impairment was assessed by the Work Productivity and Activity Impairment Questionnaire-Asthma. Odds ratios (OR) and 95% CI for asthma exacerbation risk at month 12 were generated by using multivariable logistic regression. Results: A total of 1186 patients were included. More than two-thirds of the patients (67.4%) were on ≥3 long-term controllers, and 55.1% were considered difficult to treat due to frequent exacerbations. Patients reported low asthma-related quality of life scores and considerable impairment in overall work and daily activity (21.4% and 32.1%, respectively). After adjustment for covariates, exacerbation history (hospitalization, OR 6.27 [95% CI, 3.61-10.88]; emergency department visit, OR 3.84 [95% CI, 2.50-5.91]; corticosteroid burst, OR 2.89 [95% CI, 2.18-3.82]) and very poorly controlled asthma (OR 1.95 [95% CI, 1.41-2.71] vs not well controlled) were independently associated with risk of a future exacerbation (all P < .001). Conclusion: Despite multiple long-term controller medications, patients with severe or difficult-to-treat asthma on Steps 4/5/6 therapy present with significant clinical burden and risk of future asthma exacerbations.