Abstract
Background: Adherence to medication is the cornerstone to achieve the best treatment outcome. Pharmacists are healthcare professionals found in pivotal positions to assess asthmatic patient’s adherence to medication. A brief, reliable, and valid measure of patient adherence is useful to enable the pharmacists to deliver that vital service. This study aims to develop a reliable and valid adherence assessment tool for asthmatic patients.
Methods : The Adherence to Asthma Medication Questionnaire (AAMQ-13) was developed based on an extensive literature review, followed by applying the Delphi technique, and then it was pilot-tested by 55 patients. The final AAMQ-13 was completed by 213 patients. Psychometric evaluation was assessed including reliability, criterion validity, and construct validity.
Results : The AAMQ-13 is a feasible 13 item questionnaire, as it can be completed within an average of two minutes. It has high internal validity (Cronbach’s alpha= 0.87). Criterion-concurrent validity was established by comparing the AAMQ-13 to the Test of the Adherence to Inhaler (TAI) and the pharmacy refill records. Criterion-convergent validity was established by comparing the AAMQ-13 to the Asthma Control Test (ACT) questionnaire and the Positive Health Behaviors Scale (PHBS). Construct validity was established through AAMQ-13 factor analysis which revealed two factors explaining 51.76% of the variance.
Conclusion : The AAMQ-13 is a reliable and valid questionnaire with several desirable characteristics as it has a high internal validity, good criterion validity, and strong construct validity. The AAMQ-13 is a suitable questionnaire that can identify non-adherent patients and reveal the reasons behind their non-adherence (intentional or unintentional non-adherence).
Keywords: Asthma, Adherence to medication, Compliance, Questionnaire, Self-report.

Introduction

Asthma is a controllable, but not curable disease affecting patients’ respiratory system. It is characterized by recurrent attacks of breathlessness and wheezing, which vary in severity and frequency from patient to patient (1). Over 300 million individuals worldwide live with asthma (2). The main treatments for asthma are inhalable formulations of anti-inflammatory medications (preventers) which are needed long-term and bronchodilators medications (relievers) recommended for relief only when required (1).
Data from recent studies show that asthma is still a poorly controlled condition (3). One reason for uncontrolled asthma is patients’ non-adherence to their preventer medications. This has been demonstrated repeatedly in real-life observational studies published globally during the previous 15 years; such studies highlight low rates of adherence to asthma preventer medications ranging between 14% and 50% (4).
Low adherence to inhalers results in poor asthma control, increased hospitalizations, increased mortality rates, and an increase in costs (5). Adherence is commonly defined as the degree to which patients correctly follow medical advices and take their medications in accordance with the way prescribed by the healthcare team (6).
Experts believe that non-adherence is underpinned by different reasons, and hence categorize non-adherence into different types. The two main types include: 1) intentional non-adherence (deliberate non-adherence which is associated mainly with patient beliefs) and 2) unintentional non-adherence (unplanned behavior which is mainly associated with lack of resources) (7,8).
To date, no method has been nominated as a universal gold standard method for measuring adherence. As objective measures are often costly or inconvenient; subjective measures such as patient self-reports are used more frequently in clinical or research settings. Self-report measures offer several advantages, including low cost, ability to differentiate between intentional and unintentional non-adherence, non-invasiveness, flexible to accommodate various conditions, and ease of administration. If devised well, self-report questionnaires can also provide valuable information such as the reasons behind non-adherence, beliefs about medications, and patient understanding of medications regimens (8–10). A well devised adherence questionnaire should be reasonably applicable to the patient as they attempt to respond; in the case of asthma, given inhaled medications are the mainstay of treatment, the questionnaire should refer to inhaled medications, for example, also, adherence to when required relievers is not important, hence the word ‘preventer’ medications is important to specify. These nuances make generic adherence questionnaires less applicable or relevant to asthma patients.
Some published questionnaires are long consist of 30 items (11,12), were developed with relatively small sample size (n= 43-66) (13–16), were published without a reported sensitivity and specificity (14,17–19), were published without a reported reliability (15), have a reliability below 0.7 (13,20), and were only published in English language. Therefore, there is a clear need for a reliable and valid instrument that can be used to assess asthma patients’ adherence to preventer therapy and reasons for non-adherence. Such tools are especially important for primary healthcare professionals such as pharmacists who have the opportunity to provide adherence support at the point of supply.
This study aimed to develop and validate a new self-administrable asthma adherence assessment questionnaire for use with adult patients. The purpose of the proposed tool, named as the Adherence to Asthma Medication Questionnaire (AAMQ-13), is to provide a brief, patient-friendly method of assessing adult asthma patients’ adherence to preventer medications in any healthcare setting.