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.

Estimation of inhalation flow profile using audio-based methods to assess inhaler medication adherence

Asthma and chronic obstructive pulmonary disease (COPD) patients are required to inhale forcefully and deeply to receive medication when using a dry powder inhaler (DPI). There is a clinical need to objectively monitor the inhalation flow profile of DPIs in order to remotely monitor patient inhalation technique. Audio-based methods have been previously employed to accurately estimate flow parameters such as the peak inspiratory flow rate of inhalations, however, these methods required multiple calibration inhalation audio recordings. In this study, an audio-based method is presented that accurately estimates inhalation flow profile using only one calibration inhalation audio recording. Twenty healthy participants were asked to perform 15 inhalations through a placebo Ellipta™ DPI at a range of inspiratory flow rates. Inhalation flow signals were recorded using a pneumotachograph spirometer while inhalation audio signals were recorded simultaneously using the Inhaler Compliance Assessment device attached to the inhaler. The acoustic (amplitude) envelope was estimated from each inhalation audio signal. Using only one recording, linear and power law regression models were employed to determine which model best described the relationship between the inhalation acoustic envelope and flow signal. Each model was then employed to estimate the flow signals of the remaining 14 inhalation audio recordings. This process repeated until each of the 15 recordings were employed to calibrate single models while testing on the remaining 14 recordings. It was observed that power law models generated the highest average flow estimation accuracy across all participants (90.89±0.9% for power law models and 76.63±2.38% for linear models). The method also generated sufficient accuracy in estimating inhalation parameters such as peak inspiratory flow rate and inspiratory capacity within the presence of noise. Estimating inhaler inhalation flow profiles using audio based methods may be clinically beneficial for inhaler technique training and the remote monitoring of patient adherence.

Irregular and Ineffective: A Quantitative Observational Study of the Time and Technique of Inhaler Use

BACKGROUND

Cross-sectional observational studies suggest that between 50% and 60% of patients misuse a dry powder inhaler, whereas studies with electronic monitors indicate that patients sometimes overuse/underuse their inhalers. It is not known what impact errors and erratic use have on inhaler adherence.

OBJECTIVES

The purpose of this study was to longitudinally quantify when and how patients adhered to a twice-daily preventer treatment by using a novel acoustic recording device attached to an inhaler (INhaler Compliance Assessment).

METHODS

Patients with a history of asthma or chronic obstructive pulmonary disease (n = 123) from primary care and community pharmacies were given an INhaler Compliance Assessment-adapted inhaler for 1 month. Analysis of the audio files provided quantitative information on time and technique of inhaler use.

RESULTS

Data were available for 103 patients. Twenty-one patients (20%) used their inhaler in the correct manner at the correct interval. There were 5045 audio files with attempted inhalations, of which 1204 had technique errors (24%). Errors included inadequate flow (27%), drug priming without inhalation (19%), exhalation into the inhaler (18%), and multiple inhalations (25%). On average, participants made errors 20% of the time. Of 60 doses expected to be taken in a month per person, on average 49 doses (82%) were attempted and when errors were accounted for, the average number of actual doses taken was 34 doses (57%; P < .01) comparing attempted to actual doses.

DISCUSSION

These data highlight that ineffective and irregular inhaler use is common and when combined in a single calculation indicate that only 20% of participants used their inhaler correctly and on time.

Inhaler Errors in the CRITIKAL Study: Type, Frequency, and Association with Asthma Outcomes

BACKGROUND

Poor inhaler technique has been linked to poor asthma outcomes. Training can reduce the number of inhaler errors, but it is unknown which errors have the greatest impact on asthma outcomes.

OBJECTIVE

The CRITical Inhaler mistaKes and Asthma controL study investigated the association between specific inhaler errors and asthma outcomes.

METHODS

This analysis used data from the iHARP asthma review service-a multicenter cross-sectional study of adults with asthma. The review took place between 2011 and 2014 and captured data from more than 5000 patients on demographic characteristics, asthma symptoms, and inhaler errors observed by purposefully trained health care professionals. People with asthma receiving a fixed-dose combination treatment with inhaled corticosteroids and long-acting beta agonist were categorized by the controller inhaler device they used-dry-powder inhalers or metered-dose inhalers: inhaler errors were analyzed within device cohorts. Error frequency, asthma symptom control, and exacerbation rate were analyzed to identify critical errors.

RESULTS

This report contains data from 3660 patients. Insufficient inspiratory effort was common (made by 32%-38% of dry-powder inhaler users) and was associated with uncontrolled asthma (adjusted odds ratios [95% CI], 1.30 [1.08-1.57] and 1.56 [1.17-2.07] in those using Turbohaler and Diskus devices, respectively) and increased exacerbation rate. In metered-dose inhaler users, actuation before inhalation (24.9% of patients) was associated with uncontrolled asthma (1.55 [1.11-2.16]). Several more generic and device-specific errors were also identified as critical.

CONCLUSIONS

Specific inhaler errors have been identified as critical errors, evidenced by frequency and association with asthma outcomes. Asthma management should target inhaler training to reduce key critical errors.

Characteristics of patients making serious inhaler errors with a dry powder inhaler and association with asthma-related events in a primary care setting

OBJECTIVE

Correct inhaler technique is central to effective delivery of asthma therapy. The study aim was to identify factors associated with serious inhaler technique errors and their prevalence among primary care patients with asthma using the Diskus dry powder inhaler (DPI).

METHODS

This was a historical, multinational, cross-sectional study (2011-2013) using the iHARP database, an international initiative that includes patient- and healthcare provider-reported questionnaires from eight countries. Patients with asthma were observed for serious inhaler errors by trained healthcare providers as predefined by the iHARP steering committee. Multivariable logistic regression, stepwise reduced, was used to identify clinical characteristics and asthma-related outcomes associated with ≥1 serious errors.

RESULTS

Of 3681 patients with asthma, 623 (17%) were using a Diskus (mean [SD] age, 51 [14]; 61% women). A total of 341 (55%) patients made ≥1 serious errors. The most common errors were the failure to exhale before inhalation, insufficient breath-hold at the end of inhalation, and inhalation that was not forceful from the start. Factors significantly associated with ≥1 serious errors included asthma-related hospitalization the previous year (odds ratio [OR] 2.07; 95% confidence interval [CI], 1.26-3.40); obesity (OR 1.75; 1.17-2.63); poor asthma control the previous 4 weeks (OR 1.57; 1.04-2.36); female sex (OR 1.51; 1.08-2.10); and no inhaler technique review during the previous year (OR 1.45; 1.04-2.02).

CONCLUSIONS

Patients with evidence of poor asthma control should be targeted for a review of their inhaler technique even when using a device thought to have a low error rate.

Randomized equivalence trial: A novel multidose dry powder inhaler and originator device in adult and adolescent asthma

BACKGROUND

Guideline-defined asthma control can be achieved and maintained in patients by treatment with fluticasone propionate-salmeterol (FP-Sal).

OBJECTIVE

To compare the efficacy and safety of FP-Sal delivered via a novel multidose dry powder inhaler (mDPI) versus an originator device in adolescent and adult patients with moderate-to-severe persistent asthma.

METHODS

Patients ages 12-65 years (N = 555) were randomized to treatment with FP-Sal novel mDPI 100 μg-50 μg or 500 μg-50 μg, or originator device 100 μg-50 μg or 500 μg-50 μg in a double-blind, double-dummy, parallel-group, multicenter study. Primary efficacy measures were absolute change in forced expiratory volume in 1 second (FEV1) from baseline and the area under the 12-hour serial FEV1 curve at the end of 12 weeks of treatment. Secondary end points included mean changes in FEV1; FEV1 % predicted; morning predose peak expiratory flow; daytime, nighttime, total asthma symptom scores; rescue medication use; percentage of patients with guideline-defined controlled asthma; global efficacy evaluation; patients' device preference; and safety.

RESULTS

FP-Sal mDPI and originator device-mediated increases in FEV1 from baseline to the end of treatment were not significantly different, difference in least squares mean, -0.065 L (95% confidence interval, -0.154 to 0.024 L) at 100 μg-50 μg, and -0.032 L (95% confidence interval, -0.121 to 0.057 L) at 500 μg-50 μg). Both doses of FP-Sal mDPI improved FEV1 area under the 12-hour serial FEV1 curve from baseline and all secondary efficacy measures with no significant differences from the originator device at equivalent doses, with similar safety profiles.

CONCLUSIONS

FP-Sal mDPI demonstrated equivalent efficacy and safety profile to the originator device and is an alternative in this patient group.

Minimal inspiratory flow from dry powder inhalers according to a biphasic model of pressure vs. flow relationship

Inhalation therapy using the dry powder inhaler (DPI) is now the first choice for obstructive pulmonary diseases. We previously measured relationships between inspiratory pressure (PI) and flow rate of almost all of the DPIs available in Japan, and described an importance of inspiratory efforts. In the present study, we further analyzed the data obtained in the previous study. Although there were linear relationships between PI and flow2, the slope became steeper when PI was less than a certain value (critical PI, existed between 15-20 cmH2O). When PI was less than critical PI, linear rather than parabolic regression between PI and flow yielded better fits (r > 0.90, p < 0.001). Inspiratory flows at the critical PI were 53.9 (Diskus), 65.8 (Diskhaler), 45.9 (Turbuhaler for Pulmincort), 48.6 (Turbuhaler for Symbicort) and 38.0 l/min (Twisthaler). These findings suggested that flow through the DPI becomes laminar rather than turbulent flow in the range below critical PIs. We suggest that patients should inhale from the DPIs with inspiratory pressure higher than critical PI.