Brief-interval telephone surveys of medication adherence and asthma symptoms in the Childhood Asthma Management Program Continuation Study.

BACKGROUND: Although it is known that most patients do not consistently take controller medications every day, the impact of nonadherence on asthma control is not well documented.
OBJECTIVE: To establish the relationship between medication adherence and symptom control in adolescents and young adults with asthma.
METHODS: A total of 756 adolescents and young adults diagnosed as having mild to moderate asthma on entry into the original study underwent 6 monthly telephone interviews as an ancillary project to the Childhood Asthma Management Program Continuation Study. Participants were queried about medication use and symptom control within each 1-month interview window. Strategies adopted to improve self-report accuracy included use of repeated interviews, confidential reporting to staff unknown to the participants, and use of questions focused on recent behavior.
RESULTS: Only participants who were consistently on inhaled corticosteroids (ICSs) for the entire 6-month study interval were included. Three groups of patients were contrasted: those not on ICSs (n = 420), those on ICSs with high adherence (> or = 75% of medication taken, n = 90), and those on ICSs with low/medium adherence (< 75% of medication taken, n = 148). Participants in the low/medium adherence group reported, on average, less symptom control and more variability in wheezing, awakening at night, missed activities, and beta2-agonist use during the 6-month period, although most in this group perceived their asthma to be under good control.
CONCLUSION: Despite extensive patient education and support, diminished ICS adherence was frequent and undermined symptom control in this group of adolescents and young adults with mild to moderate asthma.