Study design
An earlier population-based cross-sectional study [7] has validated the suitability of HLS-EU-Q47 for the Malaysian context. The present study also employed a cross-sectional design on the Malaysian population based on ethnic distribution to ensure that the short version instrument reflects the country’s varied ethnicities. Participants were between the age of 18 to 60 years old. Adapted measures from the HLS-EU-47 [8] validated in English and Malay in a previous study [7] were utilised. However, a 3-level face validation process was conducted and our researchers have restructured the sequence of some items to allow for better comprehension and reduce confusion for respondents. Some items were also reworded upon recommendation by health education experts through the face validation stage.
The survey was administered by well-trained interviewers working for the Ministry of Health Malaysia. Three states were selected (Selangor, Kuala Lumpur and Sarawak) to represent the distribution of multiple ethnicities, as well as the distribution of urban and rural areas. The selection of areas were made based on referral and advice by the District of Jurisdiction Malaysia, Rural Master Plan Malaysia, and previous literature [9].
Ethical Approval
This study was submitted for ethical review and received ethical approval from the National Medical Ethics Committee Malaysia which governs all medical/health related research in Malaysia. The National Medical Research Registration (NMRR) ID obtained for this study is 41882 and approval number is NMRR-18-1320/41882. The NMRR approval is the only ethical approval needed as this project was submitted under the Ministry of Health Malaysia and the National Medical Ethics Committee Malaysia is the Ministry’s Institutional Regulatory Board for Ethical Approval.
All respondents were above 18 years old and therefore involved no minors. All respondents also signed a written consent form clearly stating their rights and nature of participation in the study before being asked to answer the survey. This consent form was also submitted and approved by the National Medical Ethics Committee Malaysia.
Sampling method
Multi-stage random sampling was used in this study. Specifically, there were three stages involved, utilising several sampling techniques (quota sampling, cluster sampling and simple random sampling) to allow random data collection. The three stages are as in Figure 1. The researchers made the decision to prioritise an inclusive Malaysian sample based on ethnicity and urban/rural strata due to constraints in resources. This was to ensure that the smaller groups were adequately represented in the sample. The list of states, ethnicities and urban/rural distribution required for this study are as presented in Table 1.
In stage 1, quota sampling based on ethnicities and urban/rural distribution were used to select three Malaysian states. Ethnic distribution should be a standard in sampling multiracial populations to ensure inclusivity of the sample [10]. States from both Peninsular Malaysia and Borneo were selected to represent the diverse ethnicities in Malaysia. For the purpose of urban and rural distribution, Kuala Lumpur was selected to represent the urban area majority. This is justified as Kuala Lumpur has the highest urban population in Malaysia. Sarawak was selected to represent the rural distribution, as well as to give more balanced representation of the minority ethnic groups. Selangor represents both urban and rural areas and has a balanced ratio in ethnic group distribution. Selection of the three states was decided upon discussion between researchers and the Ministry of Health Malaysia.
In stage two, researchers utilised cluster sampling to determine districts of choice. District sampling for Selangor was determined based on the demographic distribution list published by the Selangor Economic Development Unit, as well as extant literature [9]. For selection of districts in Kuala Lumpur, researchers used data provided by the Department of Information, Ministry of Communications and Multimedia Malaysia; and for selection of districts in Sarawak, the selection of districts was guided by data provided by the State Director of the Fire and Rescue Department. The definitions of rural and urban were determined by the National Department of Statistics and The Rural Master Plan, published by the Ministry of Rural Development Malaysia.
In stage three, respondents were selected based on a simple random sampling technique based on several criteria (i.e., Malaysian, aged 18 and above, resident in the chosen state, able to make health decisions for themselves). This is also the same protocol criteria used by the Asian Health Literacy Consortium. Only one person was selected in each household, in which the eldest household member would be chosen if there was more than one person who met the respondent selection criteria (similar technique used in literature) [11].
Sample size was calculated based on the minimum requirement for CFA rule of ten [12]. Based on the 47 items, the study would need a minimum of N=470 in order to perform CFA with a 95% confidence level. However, the researchers decided to increase the number of respondents to improve the confidence interval, thereby reducing the margin of error [13].
Data collection was conducted between 25th June 2018 to 14th July 2018, involving 18 enumerators. Respondents took an average of 30-40 minutes to fill in the questionnaire.
Questionnaire and measurement
The health literacy survey questionnaire (HLS-EU-Q47) contained 47 items measuring health literacy. The perceived difficulty of each item was rated on a 4-point Likert scale which ranged from 1 = very difficult to 4 = very easy. The HLS-EU-Q47 was developed based on a conceptual model of health literacy which measures four individual competencies (the ability to access, understand, appraise, and apply health information) across three domains i.e: health care, disease prevention and health promotion [8].
Participant and data collection procedure
The enumerators went from house to house within the selected areas and provided the self-reported questionnaire to be answered. A consent form was filled in and obtained from each participant. Although the researchers aimed to collect responses from 800 respondents, a total of 866 complete responses with no missing data were obtained throughout the data collection period and analysed. All trained interviewers wore the Ministry of Health uniform and identity card to avoid misunderstanding and protect the interest of both researchers and respondents.
Data Analysis
Selection of items and validity analyses
The analysis procedures utilised in this study closely follow those conducted by previous studies [14,15,16] to allow for flexibility in exploring the relationships between variables in the model, not limited to model and item evaluation. To establish construct validity, CFA was conducted separately for the three health literacy domains of health care, disease prevention, and health promotion. The fit of the data to the model was examined using goodness-of-fit indices, including (i) absolute model fit: root mean square error of approximation (RMSEA) and goodness-of-fit index (GFI); (ii) incremental fit: adjusted goodness-of-fit index (AGFI), comparative fit index (CFI), incremental fit index (IFI), and normal fit index (NFI).
Reliability analyses
Internal consistency was tested with Cronbach's alpha, and values greater than or equal to 0.7 indicate satisfactory reliability.