Phase four: Psychometric analysis (Reliability and Validity).
The reliability, criterion (concurrent and convergent validity), construct validity, sensitivity, and specificity were assessed in this phase. The final version of the developed questionnaire was made available to another set of participants with asthma. To be included in this phase of the study, participants should be diagnosed with asthma by a specialist, prescribed regular inhaled corticosteroid inhalers for the last six months at least, and above the age of 18. The participants were asked about these inclusion criteria at the beginning of the questionnaire and were noted to only complete the questionnaire if they met these inclusion criteria. Participants were targeted through emails and social media (Facebook and WhatsApp).
Demographic information (gender, age, living place, marital status, education, employment, and smoking) were requested from the participants (22). All the questionnaires used in this phase (AAMQ-13, TAI, ACT, and PHBS) were translated from English to Arabic by qualified experts with many years of experience in translation. These experts were native speakers of the target language; they had a comprehensive knowledge of the relevant terminology and used a professional-related website in translation to ensure the accuracy of the terminologies used (27). Afterward, the translation was validated by colleagues (n= 2) who were experts in the clinical research field and in language translation. Their comments and feedback provided were considered by the research team and then incorporated where appropriate.
The reliability was assessed through the Cronbach’s alpha coefficient. The construct validity was assessed through AAMQ-13 factor analysis. The criterion-concurrent validity was assessed through subjectivemeasure (comparing the AAMQ-13 to the Test of the Adherence to Inhaler (TAI)) (28). The TAI is a validated 10-item questionnaire used to assess the adherence to inhalers in patients with asthma or COPD. It has a score range from 10 to 50 (each item has a score from 1 to 5, where 1 represents the worst possible score and 5 represents the best possible score). The cut-offs for TAI were 50 for adherent patients, 46-49 for intermediate adherent patients, and ≤ 45 for non-adherent patients (28). The criterion-convergent validity was assessed through comparing the AAMQ-13 to the Asthma Control Test (ACT) questionnaire (29), and the Positive Health Behaviors Scale (PHBS) (30). The hypothesis behind using the ACT and PHBS was that participants with higher AAMQ-13 scores were expected more than the low-scoring ones to have well-controlled asthma. In addition, participants with higher AAMQ-13 scores were more expected to score higher in the PHBS, indicating that adherent patient generally have a better lifestyle.