A Method to Calculate Adherence to Inhaled Therapy that Reflects the Changes in Clinical Features of Asthma

Abstract

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

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

“…This method of adherence calculation was previously described in detail by Sulaiman et al 31 Initially, the AUC was calculated for the patient's 'attempted adherence'. This method of adherence calculation was previously described in detail by Sulaiman et al 31 Initially, the AUC was calculated for the patient's 'attempted adherence'.…”

“…[3][4][5][6][7][8][9] For respiratory patients, some scholars argue for the incorrect use of inhalers to be a form of poor adherence or non-adherence. 9,10 Whereas a third group of scholars [27][28][29][30][31] highlight that the notion of what is called true adherence incorporates two distinct components namely adherence and competence, with competence mainly being related to the patient's ability to use a medication in a correct and effective way, which is also commonly referred to as technique. 9,10 Whereas a third group of scholars [27][28][29][30][31] highlight that the notion of what is called true adherence incorporates two distinct components namely adherence and competence, with competence mainly being related to the patient's ability to use a medication in a correct and effective way, which is also commonly referred to as technique.…”

Severe asthma in children

“…Even electronic monitoring does not prove the medication was correctly inhaled, and the addition of an audio signal reveals that actual adherence is less than that determined by simple electronic signals. 62 Managing non-adherence remains one of the biggest challenges of the severe asthma clinic. If all else fails, consideration should be given to directly observed therapy (described below).…”

‘We can’t diagnose asthma until <insert arbitrary age>’

“…The report highlighted the numerous social and environmental traits that were treatable but not addressed, in particular adherence to ICS, overuse of bronchodilators and failure to attend review appointments 2. Adherence is a particularly important aspect that the Commission discusses; we cannot rely on asking the patient—we have to use more objective measures 40. Thus, the Commission proposes a new and broader definition of severe asthma.…”