The final sample included 958 observations from 494 individuals (mean age at baseline 52.2 ± 14.5 years; 67.0% women). Asthma was symptomatically controlled, partially controlled, and uncontrolled in 269 (28.1%), 367 (38.3%), and 322 (33.6%) observations, respectively. A person with symptomatically uncontrolled asthma would gain 0.0512 (95% CI 0.0339–0.0686) in EQ-5D or 0.0802 (95% CI 0.0693–0.0910) in AQL-5D utilities by achieving symptom control. The loss of predictive efficiency was 55.4% and 27.6% for EQ-5D and AQL-5D utilities, respectively.