การพัฒนาแบบวัดทักษะที่บ่งบอกความแตกฉานทางสุขภาพสำหรับคนไทย ตามวิธีการของ Health literacy skills instrument

Abstract

This study aimed to develop a reliable and valid measure called the Thai Health Literacy Skill Assessment (THLA-S) using the approach in the Health Literacy Skills Instrument (HLSI), and to determine the cut-off value to interpret the level of health literacy (HL). The initial scale consisted of 26 items. After revision according to the opinion of 6 experts, the THLA-S was tested with 522 accidentally selected outpatients and relatives in a hospital. The subjects completed the THLA-S questionnaires on various HL indicators, including Thai Health Literacy Assessment Using Nutrition Label (THLA-N). Item analysis found that less than 6 percent of subjects correctly answered the questions 24 (calculation using data from nutrition labels) and 26 (reading and calculation from bar graphs). The study therefore eliminated these question because of their poor discriminating ability on HL. While item 3 (understanding the information about cholesterol) exhibited a correlation of 0.199 with the total score of THLA-S and therefore was eliminated as well. The remaining 23 items of the THLA-S were consistent to the structure of the HLSI. The scale measured print literacy (10 items), document literacy (such as tables) (10 items), speaking-listening skills (4 items) and internet skills for seek information (2 items). The skills measured by the THLA-S included identification and understanding of health information (6 items), interpretation of health information (11 items), summarizing information or applying data to a particular situation (5 items), calculation (2 item) and using the internet to seek information (2 items). The content of the test consisted of 3 domains including health promotion-disease prevention (17 items), treatment and utilization of health services (5 items) and access to services in health systems (4 items). The THLA-S showed a satisfactory Cronbach's alpha of 0.815. The THLA-S measurement was valid because 1) those reporting that the performing of 6 activities (from all 8 activities) was easy or very easy (such as calculating numbers, remembering data, seeking information, etc.) had a higher level of the THLA-S score than those reporting the tasks as very difficult or difficult 2) those with a higher education levels showed a higher level of the THLA-S scores 3) the relationship of the THLA-S score and HL indicators was positive and statistically significant. The relationship between the THLA-S and self-assessment of ability to read, the ability to read measured by the cloze test, the ability to screening tests for inadequaete health literacy, the ability to use nutrition labels and the THLA-N were 0.336, 0.398, 0.156, 0.634 and 0.606, respectively. Analysis of the receiver operating characteristic curve using the THLA-N as a gold standard revealed that the THLA-S had an AUC of 0.838, indicating that the ability of the measurement to separate those with adequate and inadequate HL was at the moderate to high level. Those with the THLA-S score less than or equal to 13 were considered to have inadequate HL. At this cut-off, the scale had a sensitivity of 75.0 percent, specificity of 78.4 percent, PPV of 79.12 percent and NPV of 74.19 percent, with LR+ and LR- of 3.47 and 0.32 respectively. Overall, the scale is valid, reliable, sensitive, and specific with an accurate discriminating power of HL. However, the THLA-S still needs further improvement because of its lengthy number of items.