Asthma control, severity, and quality of life: quantifying the effect of uncontrolled disease.

BACKGROUND: Current practice guidelines emphasize the importance of attaining asthma control. We sought to quantify the degree of quality-of-life impairment associated with different levels of asthma control.
METHODS: We analyzed prospective data for 987 adults in The Epidemiology and Natural History of Asthma: Outcomes and Treatment Regimens (TENOR) study. Asthma control was assessed by using the Asthma Therapy Assessment Questionnaire, a validated index of control problems ranging from 0 to 4. Disease-specific quality of life and preference-based health utilities were assessed after 12 months of follow-up by using the Mini-Asthma Quality of Life Questionnaire (AQLQ) and EuroQoL 5-D (EQ-5D). We used multiple linear regression to model the relationship between asthma control and the AQLQ and EQ-5D while controlling for severity classification and lung function.
RESULTS: Asthma control varied widely, even within a population with predominantly moderate-to-severe disease. An inverse relationship was observed between the number of asthma control problems and quality of life. Specifically, poorer control at baseline predicted worse AQLQ and EQ-5D scores at follow-up. Asthma control remained an independent predictor of disease-specific quality of life and general health in multivariate models and was a better longitudinal predictor of health status than asthma severity at baseline.
CONCLUSION: Poor asthma control is associated with a substantial degree of impairment and predicts quality of life at 12 months, even after taking baseline asthma severity into account. CLINICAL IMPLICATIONS: Self-assessed measures of asthma control might help to identify and manage those patients at greatest risk for future health impairment.