Measurement of children's asthma medication adherence by self report, mother report, canister weight, and Doser CT.

BACKGROUND Accurate assessment of medication adherence has been difficult to achieve but is essential to drug evaluation in clinical trials and improved outcomes in clinical care. OBJECTIVE This study was conducted to compare four adherence assessment methods: child report, mother report, canister weight, and electronic measurements of metered dose inhaler (MDI) actuation. METHODS Participants included 27 children with mild-to-moderate asthma who were followed prospectively for 6 months. All patients used an MDI equipped with an electronic Doser attached to their inhaled steroid. At each 2-month follow-up visit, Doser and canister weight data were recorded, while child and mother were interviewed separately regarding medication use. RESULTS Children and mothers reported, on average, over 80% adherence with the prescribed inhaled steroid. Canister weight revealed, on average, adherence of 69%, significantly lower than self-report. When adherence recorded by the electronic Doser was truncated to no more than 100% of prescribed daily use, average adherence was 50%. Older children and adolescents, nonwhite children, and those from poorer functioning families were least adherent. CONCLUSIONS Electronic adherence monitoring was significantly more accurate than self-report or canister weight measures. Such accuracy is an essential prerequisite to increasing understanding of the treatment, setting, and patient factors that influence adherence, and to the consequent design of effective intervention strategies.