Test of the Thai Health Literacy Assessment Based on Ability to Use Nutrition Label and Health Literacy among Clients in Public Hospitals within Nakhon Si Thammarat

Abstract

Objective: To test validity and reliability of the Thai Health Literacy Assessment Instrument: Nutrition Label (THLA-N8), to determine cut-off used to interpret the HL level measured by the THLA-N8 and to find the percentage of clients with inadequate HL in outpatient departments in hospitals under the Ministry of Public Health in Nakhon Si Thammarat. Methods: Test of validity and reliability of the THLA-N8 was conducted in a total of 1,003 patients (503 from a community hospital and 500 from a general hospital). Validity was tested by determining the difference of average THLA-N8 scores among subjects with different education levels, and assessing relationship between the THLA-N8 and the ability to understand health documents and the HL-related questions taken from the Thai Health Literacy Skills Instrument (THLA-S). The study used the receiver operating characteristics (ROC) curve analysis to find the cut-off for interpreting scores by using the ability to understand health documents as the first gold standard (GS1) and sum of the ability to understand health documents and the score from 4 questions of the THLA-S as GS2. The study estimated the percentage of clients with inadequate HL in 1,100 subjects in outpatient department of 23 hospitals under the Ministry of Public Health in Nakhon Si Thammarat. Results: Cronbach coefficient of the THLA-N8 was 0.71. The test was valid i.e., those with higher education levels having a higher THLA-N8 scores than those with lower education levels (P <0.001). THLA-N8 had statistically significant and positive correlations with 2 HL indicators i.e., understanding of health documents and sum of 4 questions from the THLA-S (r = 0.52 and 0.47 respectively). ROC curve analysis showed that the THLA-N8 had the area under the curve of 0.76 and 0.82 when using GS1 and GS2 as gold standard, respectively, implying that the test could well discriminate those with adequate and inadequate HL. THLA-N8 score less than or equal to 4.83 indicated inadequate HL. The test’s sensitivity were 0.75 and 0.80, with specificity of 0.67 and 0.74 when using GS1 and GS2 as gold standard, respectively. When using cut-off point of the THLA-N at 4.83 to screen the subjects, in overall there were 51.90% of subjects with inadequate HL. 51.72 to 100.00 per cent of those with primary school to high school education and vocational certificate in all age groups (20 to 80 years) were considered having inadequate HL. 36.08 - 49.21 percent of those with a higher vocational certificate, college degree or higher in all age groups (20 to 80 years) were considered having inadequate HL. Conclusion: Overall, the THLA-N8 is valid, reliable, sensitive and specific at a satisfactory level, similar to the findings in previous research. The THLA-N8 can be used to screen service clients in the health system. Percentage of people with grade 10-12 or vocational certificate or lower in all age groups with inadequate HL was about 50.00 percent or more. Problems are more common in the elderly.