In severe asthma, poor control could reflect issues of medication adherence or inhaler technique, or that the condition is refractory. This study aimed to determine if an intervention with (bio)feedback on the features of inhaler use would identify refractory asthma and enhance inhaler technique and adherence.Patients with severe uncontrolled asthma were subjected to a stratified-by-site random block design. The intensive education group received repeated training in inhaler use, adherence and disease management. The intervention group received the same intervention, enhanced by (bio)feedback-guided training. The primary outcome was rate of actual inhaler adherence. Secondary outcomes included a pre-defined assessment of clinical outcome. Outcome assessors were blinded to group allocation. Data were analysed on an intention-to-treat and per-protocol basis.The mean rate of adherence during the third month in the (bio)feedback group (n=111) was higher than that in the enhanced education group (intention-to-treat, n=107; 73% 63%; 95% CI 2.8%-17.6%; p=0.02). By the end of the study, asthma was either stable or improved in 54 patients (38%); uncontrolled, but poorly adherent in 52 (35%); and uncontrolled, but adherent in 40 (27%).Repeated feedback significantly improved inhaler adherence. After a programme of adherence and inhaler technique assessment, only 40 patients (27%) were refractory and adherent, and might therefore need add-on therapy.

These data may inform clinicians in understanding why a prescribed inhaler is not effective and to devise strategies to promote adherence in COPD.

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RationalePoor adherence to inhaler use can be due to poor temporal and/or technique adherence. Up until now there has been no way of reliably tracking both these factors in everyday inhaler use.ObjectivesThis paper introduces a device developed to create time stamped acoustic recordings of an individual's inhaler use, in which empirical evidence of temporal and technique adherence in inhaler use can be monitored over time. The correlation between clinical outcomes and adherence, as determined by this device, was compared for temporal adherence alone and combined temporal and technique adherence.FindingsThe technology was validated by showing that the doses taken matched the number of audio recordings (r2 = 0.94, p<0.01). To demonstrate that audio analysis of inhaler use gives objective information, in vitro studies were performed. These showed that acoustic profiles of inhalations correlated with the peak inspiratory flow rate (r2 = 0.97, p<0.01), and that the acoustic energy of exhalations into the inhaler was related to the amount of drug removed. Despite training, 16% of participants exhaled into the mouthpiece after priming, in >20% of their inhaler events. Repeated training reduced this to 7% of participants (p = 0.03). When time of use was considered, there was no evidence of a relationship between adherence and changes in AQLQ (r2 = 0.2) or PEFR (r2 = 0.2). Combining time and technique the rate of adherence was related to changes in AQLQ (r2 = 0.53, p = 0.01) and PEFR (r2 = 0.29, p = 0.01).ConclusionsThis study presents a novel method to objectively assess how errors in both time and technique of inhaler use impact on clinical outcomes.Trial Registration EudraCT 2011-004149-42

Written permission has been obtained from all persons named in the acknowledgment.Author Contributions: EM, SOD and SR were primarily involved in patient recruitment. SD, VR, IK and RBR were primarily involved in the audio analysis required for this manuscript. FB was primarily involved in the statistical analysis for this manuscript. BC, and MCM were involved in data collection and data analysis for this manuscript. IS, JS and RWC were involved in all aspects required for this manuscript including patient recruitment, data management, data analysis and were the primary leads in the design of the work. All co-authors were involved in writing and editing this manuscript. Methods:We attached a digital audio device (INCA TM ) to a dry powder inhaler. This recorded when the inhaler was used and analysis of the audio data indicated if the inhaler had been used correctly. These aspects of inhaler use were combined to calculate adherence over time, as an AUC measure. Over a 3 month period a cohort of asthma patients were studied. Adherence to a twice-daily inhaler preventer therapy using this device and clinical measures were assessed. Measurements and Results:Recordings from 239 patients with severe asthma were analysed.Average Adherence, based on the dose counter was 84.4%, whereas the ratio of expected to observed accumulated AUC, Actual Adherence, was 61.8% (p<0.01). Of all adherence measures, only adherence calculated as AUC reflected changes in asthma quality of life, beta agonist reliever use and PEF, over the three months (p<0.05 compared to other measures of adherence). Conclusion:Adherence that incorporates the interval between doses and inhaler technique, and calculated as AUC, is more reflective of changes in quality of life and lung function than the currently used measures of adherence. Electronic monitors are considered to be the gold standard for objectively quantifying adherence (1). Most studies using electronic recording devices have reported adherence as the mean adherence or, the Mean Daily Dose, over the study period (2) (3) (4) The aim of this study was to test the hypothesis that by including the time of use, the interval between doses and accounting for inhaler technique, we could quantify adherence as an Area Under the Curve (AUC) and, furthermore, determine whether adherence calculated using AUC was more reflective of patient outcomes than current methods of assessing adherence. Some of the results of this study have been previously reported in the form of an abstract(18). Methods

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Acoustically-determined PIFR is a suitable method for estimating drug delivery and for monitoring inhalation technique over time.

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