Change in asthma control over time: predictors and outcomes.

BACKGROUND: Maintenance of asthma control over time is a clear goal of national asthma guidelines, but few studies have addressed the natural history of asthma control over time.

OBJECTIVE: To assess the impairment domain of asthma control over time in patients with persistent asthma and to determine predictors and consequences of controlled and uncontrolled asthma over time.

METHODS: Patients 18-56 years old with persistent asthma who completed baseline (November 2007) and follow-up asthma surveys (April, July, October 2008) were included in the study. The survey included the Asthma Control Test as well as questions regarding other patient and asthma characteristics. Health care utilization (pharmacy and exacerbations) for 2008 was obtained from administrative data.

RESULTS: The baseline and first follow-up surveys were completed by 1267 patients, and all 4 surveys were completed by 782 patients. Patients with well-controlled asthma at baseline were significantly more likely (P < .0001) to have well-controlled asthma over the following year (76.2%-80.4%) than patients with uncontrolled asthma at baseline (33.5%-36.9%). Patients whose asthma control improved over the first several months of follow-up experienced significantly (P < .05) fewer exacerbations over the subsequent year than patients with initially uncontrolled asthma who did not improve.

CONCLUSION: Degree of asthma control at one point in time is strongly related to the achievement or maintenance of control and to asthma exacerbations over time. Patients with uncontrolled asthma, especially very poorly controlled asthma, should receive intensive management and follow-up in an attempt to achieve well-controlled asthma over time.