On inclusion criteria, participants will be recruited for this study if they are (a) at least 18 years old, (b) diagnosed with hypertension defined as persistent elevation of systolic blood pressure of 130 mmHg or greater and/or diastolic blood pressure of 80 mmHg or greater, or currently prescribed with anti-hypertensive drugs, (c) have received anti-hypertensive drug treatment for at least 6 months, and (d) able to communicate in English language or Malay language. Psychiatric patients are eligible, if they are (a) aged at least 18 years old, (b) able to give consent independently, and (c) have no suicidal tendency at the time of study recruitment. Written consent forms, patient information sheets describing the study, and the ethical approval letters will be provided to the participants who agree to participate to the study.
On exclusion criteria, no participants will be recruited for this study if they are diagnosed with (a) secondary hypertension such as parenchymal kidney disease, renovascular disease, primary aldosteronism, Cushing syndrome, and phaeochromocytoma, (b) malignancies, (c) cognitive impairment and mental health disorders such as schizophrenia, major depressive disorder, generalised anxiety disorder, and dementia, and (d) pregnant. Patient history and medical record will be used to establish exclusion criteria.
A semi-structured interview schedule will be developed with reference to the Capability, Opportunity, Motivation, and Behaviour (COM-B) model so as to explore the experience of taking anti-hypertensive drugs, including the determinants of them being non-compliant towards the prescribe medications (Appendix A). The COM-B model consists of 3 main domains namely capability, opportunity, and motivation. The interplay of capability, opportunity, and motivation could affect individuals’ behaviour of taking medication . In particular, we will use the four-step Interview Protocol Refinement (IPR) Framework to develop the interview schedule to ensure validity and reliability . In Step 1, we will design a series of open-ended questions in the interview schedule in line with our research objective as described above. In Step 2, we will construct all interview schedule questions in an inquiry-based conversation fashion (e.g., can you please share with me regarding your experience with high blood pressure?) and in English so that participants from different sociodemographic subgroups can easily comprehend the questions. In Step 3, we will invite two members of the supervisory committee and an external primary care physician to independently review the interview schedule and provide feedback. In Step 4, we will test the newly developed interview schedule with two hypertensive patients, one from each health clinic. Subsequently, an independent translator will translate the validated interview schedule into Malay and Mandarin.
All interview sessions will be conducted in a quiet meeting room at the clinics. We will begin our interviews by discussing the purposes of the interview. In an effort to build rapport, participants will be asked to introduce themselves. They will also be encouraged to freely share their own thoughts and ideas. We will elicit the themes of compliance and non-compliance towards anti-hypertensive drugs among the participants through all questions in the interview schedule. We aim to complete the interviews within 45 minutes. All interviews will end with the interviewer’s reflection. All interviews will be audiotaped and transcribed verbatim. Recruitment of participants will proceed until the point of thematic saturation. All data collected will remain private and confidential.
After each interview, we will save the audio files in a password-secured laptop and transcribe verbatim the audio using NVIVO software. Transcripts will be then checked against the audio recording of each interview to ensure accuracy. Participant names will be replaced with coded names for confidentiality purpose. Should the interviews be conducted in Malay or Mandarin, we will translate the recordings back into English. A constant comparative method will be used for analysis. Specifically, we will read through the transcripts before extracting and coding the meaning units. Then, we will categorize the codes. We will ensure the quality and rigor of the qualitative inquiry through the tests of credibility, transferability, dependability, and confirmability.
We aim to achieve the credibility of the current study through triangulation and member checks. In the process of triangulation, two independent investigators will analyse the same set of data independently and to compare findings. Member checks will also be performed by taking the analysed data back to the hypertensive patients for verification. We will ensure dependability through peer review and researcher reflexivity. Peer review will be done by inviting a qualitative researcher to go through part of the raw data and to examine whether the research findings are plausible in accordance to the interview data. In addition, the interviewers will also clearly mention their dispositions, biases, worldview, assumptions, theoretical orientation, and relationship to the study that may affect the investigation. We aim to achieve transferability through rich and thick description of the study setting and the characteristics of the participants (e.g., age, gender, ethnicity, & level of education of the hypertensive patients). Confirmability will be ensured through the provision of verbatim .
All audio recordings will be de-identified, and there will be no mention of personal identifying information (e.g., names, identification card number, and address) during the interview. All audio recordings are for transcription purposes and will not be copied or transferred to any other parties or used for any other purposes. After transcription, the audio recordings will be disposed securely. We will store all audio recordings in the form of voice recording MP3 until the completion of transcription, while the transcription will be saved as Microsoft Word format in a password-secured computer. Only the principle investigator and coordinator investigator will have access to the data.
We will conduct a quantitative study to develop and validate the Malaysian Anti-hypertensive Agents Compliance Scale (MAACS) in a sample of hypertensive patients. This quantitative study is cross-sectional by design.
The preliminary version of the MAACS will consist of themes that generated from Study 1, which aimed at identifying determinants of hypertension treatment compliance. Based on these themes, we will create the preliminary MAACS items. Thirty participants will be asked to individually and independently evaluate and score each preliminary MAACS item for its appropriateness, representativeness, and explicitness using a 4-point Likert scale ranging from 1 (irrelevant and should be deleted) to 4 (relevant, clear, and precise). Statistically, only items with a mean score of 3.0 or above will be retained. The decision about whether to retain any preliminary MAACS items scoring below 3.0. rests with the experts. An experts’ panel meeting will be conducted by A.I.N.M.N., K.A.T., S.Q.Y, and A.B. for determining the appropriateness of either deleting or retaining each item. Hence, the preliminary version of the MAACS.
The Pilot Version
Pilot testing helps to ensure that items are meaningful to the Malaysian hypertensive population. The pilot study is needed to minimise misunderstanding and subsequent measurement error , and to eliminates poorly worded items . We will conduct cognitive interviews with 5 to 15 hypertensive patients. During the interview, participants will have chance to augment, clarify, and modify each preliminary MAACS item so that the item is clear, culturally accepted, and not time consuming. This process will result in the pilot version of the MAACS.
In Study 2, data collection and participant recruitment will also take place at the two participating health clinics located in Kuala Lumpur as in Study 1. A random sampling will be conducted to select eligible hypertensive patients who attend these two clinics from December 2019 to December 2020.
As for sample size calculation, we would require at least 200 participants when taking structural equation modelling into consideration . Hence, a final sample of 400 participants will be recruited. Of these, data from 200 participants (serving as the calibration sample) will be subjected to exploratory factor analysis (EFA) and data from 200 participants (serving as the validation sample) will be subjected to confirmatory factor analysis (CFA). All participants will be selected according to the same inclusion and exclusion criteria as described in Study 1.
Participants will complete a research questionnaire containing sociodemographic items (e.g., age, gender, ethnicity, level of education, marital status, employment status, duration of hypertension, blood pressure, & medication use), the pilot version of the MAACS, and the TAQPH.
Data Analytic Plan
The Modified Version
We will examine the factor structure of the pilot version of the MAACS with the calibration sample. A principal-component analysis with promax rotation will be conducted to determine the factor structure of the pilot version of the MAACS. In particular, the following criteria will be used to determine the number of factors in the instrument: eigenvalues > 1, and items with loadings of .4 or greater on any one factor. When this was done, we will obtain the modified version of the MACCS.
The Final Version
We will examine the factor structure of the modified version of the MACCS with the validation sample. CFA will be performed to examine the goodness-of-fit of the MACCS measurement model. In particular, The MACCS measurement model will be evaluated by chi-square (χ2) test, Goodness of Fit Index (GFI), Adjusted Goodness of Fit Index (AGFI), Comparative Fit Index (CFI), Root Mean Squared Error of Approximation (RMSEA), Non-Normed Fit Index (NNFI) and Standard Root Meansquare Residual (SRMR). Acceptable model fit is indicated by χ2/df < 3.0, RMSEA < .08 and SRMR < .8. The values of GFI, AGFI, CFI, and NNFI indices should be .90 or greater . This will result in the final version of the MAACS.
Test for Validity
To establish concurrent validity, we will examine the Pearson’s r correlations between the final version of the MAACS and the TAQPH . The 28-item TAQPH is a self-report scale designed to identify determinants of compliance and non-compliance towards anti-hypertensive medications . Participants rate items on a 4-point Likert scale ranging from 1 (never) to 4 (all of the time). The TAQPH has 2 domains: medication and lifestyle. Scores on these domains are summed to obtain a total score with higher scores representing better compliance.
Test for Reliability
The internal consistency of the final version of the MAACS will be measured by Cronbach’s alpha coefficient. An alpha coefficient > .80 is referred to as high .