Measuring adherence with the Doser CT in children with asthma.

Non-adherence with prescribed asthma treatment causes compromised treatment effectiveness, including greater morbidity, mortality, and health care utilization costs. As a result, there is an increasing interest in measuring patient adherence behaviors. Electronic monitoring devices offer a promising method for assessing patient adherence behavior patterns. The reliability of the Doser Clinical Trials (CT) (Meditrack Products, Hudson, MA), an inexpensive, pressure-actuated device that monitors metered-dose inhaler (MDI) usage, was evaluated in a field study of outpatient pediatric asthmatics. Canister weight and various Doser CT measures of patient medication use were compared to determine the reliability and usefulness of the device. Doser CTs were dispensed to 16 research subjects for use on corticosteroid MDIs over a period of several months. One Doser CT per month was dispensed to each subject. Doser CTs were collected at 30-60 day intervals, with a total of 61 months of Doser CT data obtained across the subjects. MDI canister weights were monitored for a subset of 6 subjects. Usable Doser CT data were summarized and average adherence estimates were computed. Adherence estimates differed from one another and the adherence estimate, as measured by canister weight, was significantly higher than each Doser CT estimate. However, overall, the Doser CT showed adequate reliability as evidenced by high correlations among the Doser CT estimates of adherence and the existing gold standard of canister weight. The Doser CT is likely to be useful for monitoring MDI use in clinical care and research, potentially providing greater accuracy than the standard of canister weight.