Abstract
Background Rational drug use literacy is an ultimate goal in healthcare system of Thailand. It
is necessary to analyze the characteristics of the target group for the design of measures or
activities to be specific and effective for the particular target group. This study aims to develop
a tool to measure the rational drug use literacy for diabetic and hypertensive patients to be
used as a screening tool for the rational drug use literacy of patients receiving services at a
hospital, to know the situation of the rational drug use literacy of diabetic and hypertensive
patients, and to analyze the factors affecting the rational drug use literacy. Therefore, medical
personnel and healthcare service agencies can use it to promote the rational drug use literacy
of patients.
Methods This study is divided into 2 phases: Phase 1 is the development and validation of
the modified version of the rational drug use literacy tool (MF-RDUL). Both qualitative and
quantitative research methods were used, including, factor analysis and relationship between
questions, and cognitive interviews along with an expert meeting. Then, the validity and
reliability of the MF-RDUL tool were tested with sample in 5 provinces. In the final step, the
proposals of potential users were listened to before being used in a national survey. Phase 2
was to survey the norms of rational drug use literacy in diabetic and hypertensive patients in
13 provinces from 13 health area across Thailand. The factors affecting rational drug use
literacy were analysed. The independent variables were age, education level, chronic diseases,
and residential area. The dependent variable was rational drug use literacy.
Resul t s The results of the phase 1 study showed that the developed MF-RDUL14 had
satisfactory reliability, validity, sensitivity, and specificity. The questions of the MF-RDUL14
were adapted from the LF-RDUL (Rational Medicine Knowledge Assessment Scale). Cluster
principal component analysis was used to confirm the construct validity. The overall
Cronbach's alpha reliability was 0.671, the AUC (Area under the curve) was 0.793, and the cutoff value between those with and without knowledge was 9.5 (total score of 14). The results of the study in phase 2 found that the dimensions found to have a problem of insufficient
rational drug use literacy were the dimension of understanding about the importance and
benefits of taking medicine continuously and the dimension of searching for information about
herbs or supplements and the precautions and side effects of the medicine used.
Conclusion The MF-RDUL14 tool can be used as a screening tool for diabetic or hypertensive
patients who have insufficient rational drug use literacy. It is recommended to use the entire
tool, which is 14 questions to measure drug use literacy in all dimensions
