Use of metered-dose inhaler electronic monitoring in a real-world asthma randomized controlled trial

Background Electronic monitoring of inhaled asthma medications is one method to measure medication adherence and patterns of use. Information on the performance of monitors in a randomized controlled trial allows researchers and clinicians to understand their utility and limitations. The Smartinhaler Tracker is an electronic monitor for metered-dose inhalers (MDIs) that records the date, time, and number of actuations. Objective To determine the performance of the Smartinhaler monitors used in a 24-week randomized controlled trial of 303 patients with asthma in a real-world setting. Methods Prestudy use checks involved 2 actuations of the MDI, with a further 2 performed 2 hours later. Within-study monitor checks, performed before dispensing at clinic visits 2 to 4, included a computerized check of monitor clock function, actuation accuracy, and battery life. Within-study data checks involved computerized checks of monitor clock function before data upload. Results Two thousand six hundred seventy-eight of 2728 monitors (98.2%) passed prestudy use checks. Seventy-six of 2642 monitors (2.9%) dispensed to participants failed within-study monitor checks. Fifty-one of 2642 monitors (1.9%) malfunctioned before data upload, mostly as a result of fluid immersion. Ninety-three of 2642 monitors (3.5%) were lost or thrown away by participants. Complete data was available from 2498 of 2642 dispensed monitors (94.5%) and 2498 of 2549 returned monitors (98.0%). Conclusions The Smartinhaler Tracker is a reliable monitor for measuring MDI use in a real-world setting. Use of extensive monitor and data-checking protocols reduces data loss. In a research or clinical setting, the use of a validated and reliable electronic monitor represents the reference standard for assessing patterns of medication use