A quantitative evaluation of adherence and inhalation technique among respiratory patients: An observational study using an electronic inhaler assessment device.

BACKGROUND: Problems related to poor adherence and inhaler technique (IT) are historically reported in the literature. Most common methods used for adherence and IT assessment are reported to be either inaccurate or subjective. Few electronic monitoring devices (EMDs) that provide an objective measure of both adherence and IT while patients use inhalers at home now exist. Therefore, this study aimed to examine adherence level and IT among respiratory patients in community care using such an EMD for the first time in England.

METHODS: A prospective, multicentre, observational cohort study was conducted. Patients with chronic obstructive pulmonary disease (COPD) or asthma were recruited from independent community pharmacies within West and South London. Patients were provided with a dry-powder inhaler (DPI) mounted with an EMD to use for 1 month. Adherence was also assessed using pharmacy dispensing data, inhaler dose counter and self-reporting.

RESULTS: Data were available for 48 patients. Only eight patients used their inhaler in the correct manner at the correct interval as identified by the chosen EMD. The median actual adherence rate, as measured by the EMD, was 42.7%. This was significantly different from the median dose counter adherence (100%), medication refill adherence (MRA) (100%), proportions of days covered (PDC) (97.8%) and self-reported adherence (P < .001, each). Within a 1-month period, there were 2188 files showing attempted use of the DPI, of which 840 had IT errors. The median technique error rate (TER) was 30.1%. Most common errors recorded were as follows: multiple inhalations, drug priming without inhalation and failure to prime the device correctly.

CONCLUSION: The current study demonstrates that measures such as dose counter, prescription refill and self-reporting showed a high level of adherence among the observed patients. However, the objective data provided by the EMD showed a significantly lower actual adherence rate, reflecting how adherence remains variable and problematic among patients in the community.