Measuring medication adherence in asthma: Development of a novel self-report tool.

OBJECTIVE: This study presents the development and validation of MIS-A (Medication Intake Survey-Asthma), a new self-report instrument measuring key adherence properties during long-term asthma treatment.

DESIGN: Within a longitudinal asthma cohort study in France and the United Kingdom, adult patients and caregivers of children responded to computer-assisted telephone interviews.

MAIN OUTCOME MEASURES: Scores for distinct adherence properties (taking adherence, correct dosing, therapeutic coverage, drug holidays, overuse) and composite measures were computed for several time intervals. We examined distributions, longitudinal variation, associations between adherence scores and concordance with adherence calculated from medication prescribing or dispensing records.

RESULTS: Nine hundred and two participants reported on adherence to 4481 medications on 4140 occasions. About 59.47 and 70.36% revealed < 100% taking adherence in the last week and month; 42.76% had a drug holiday of > 1 week in the last 4 months. Adherence varied within patients during the follow-up (intra-class correlation = . 41-.71). Correlations between adherence scores were moderate to strong (ρ = .51-.85, p ≤ .001), except medication overuse (ρ = .04-.19, p ≤.05). Four-month taking adherence was associated with dispensing adherence, but not with prescribing adherence (ρ = .33, p < .001; and .12, p = .26).

CONCLUSION: MIS-A is a promising, easy-to-use self-report tool that can capture accurately different adherence properties over a long time period.