Testing the reliability of old and new features of a new electronic monitor for metered dose inhalers

Background: Poor adherence to treatment regimens is hypothesized to be, in part, responsible for the extensive morbidity and mortality associated with asthma. Electronic monitors are the most accurate means available for measuring adherence, but their use has been limited by reports questioning the reliability and validity of their data. Objective: To test the reliability and accuracy of the MDILog (Medtrac Technologies, Lakewood, CO), a new electronic monitor of metered dose inhalers (MDIs), and to test its unique features. Methods: Brief experiments were performed comparing a written diary to the electronic record using three MDILogs. The following features were studied: reporting of time and date of an actuation, recording of the occurrence of an actuation of the MDI, sensing and timing of inhalations, sensing of shaking of the MDI canister, and recording of multiple actuations. Results: Clocking was accurate 100% of the time. Actuation agreed with the paper record 97% to 100%, inhalation 82% to 100%, shaking 86% to 95%. Agreement of late inhalations and multiple actuations with paper records was at least 98%. Conclusions: The MDILog yields accurate information and is more reliable than previously described monitors. Its new features allow more detailed study of how patients use inhalers by allowing evaluation of how patients inhale and whether they shake the inhaler canister before use.