With the information derived from the NC, physicians can gain a better understanding of their patients’ inhaler use patterns and provide direct feedback on the appropriateness of inhaler use in an effort to improve adherence to the prescribed regimen. A limitation of the NC is that the currently available chronolog design is compatible with only a press-and-breathe MDI and not with breath-activated inhaler devices, such as a powder inhaler. Furthermore, patients with both asthma and COPD often use more than one type of MDI, thus complicating the ability to monitor each type of inhaler use in a clinical setting, unless additional NC devices dedicated to each type of MDI were used.
Current measures of adherence, including the NC, cannot determine whether the medication delivered by an MDI was inhaled properly or inhaled at all. Improper inhaler technique and test actuations into the atmosphere limit the validity of the NC. Even the feedback participants could have tried to appear compliant by actuating their inhalers into the air at the appropriate times, although it appears unlikely that a participant would remember to do this on a regular basis over the course of 4 months. It is not inconceivable that some participants might carry out this practice sporadically. Participants were instructed not to test the inhaler before each set as a way of making sure that it was working properly. Nevertheless, at follow-up some participants reported using this technique, particularly when the canister was nearing empty. A portion of the sets with three actuations may have resulted from this priming technique.
In conclusion, utilizing EM Ms in a clinical trial to provide detailed feedback on patterns of inhaler use can significantly enhance patient adherence as well as provide a highly accurate record of patient usage. Whether similar beneficial effects can be achieved with the NC in clinical practice remains to be determined.