Psychometric properties of the Taiwanese version of the Illness Concept Scale: relation of health beliefs to psychopathology and medication compliance

Purpose This paper describes the development of a Taiwanese version of the Illness Concept Scale (ICS) and assesses the psychometric properties of this instrument. The ICS is one of the few tools available to measure a global level of illness concepts or health beliefs and has been widely used in a range of clinical and research settings. The ICS has already been translated into several languages, but there is no validated Taiwanese version. Methods The English version of the ICS was translated into Taiwanese (ICS-T) and applied in this study. A total of 192 participants with and without psychoses completed the ICS-T and additional evaluations to assess psychopathology and medication compliance. Psychometric properties (factor structures and various types of reliability and validity) were assessed for this translated questionnaire. Results Overall, the ICS-T showed good reliability and stability over time. Its scale is comprised of a seven-factor solution, as in the original ICS. Following the validation of the internal structure of this scale, we obtained the total ICS-T score, representing the measurement of an individual’s illness concepts by subtracting the scores of the guilt, idiosyncratic assumption, and negative expectation subscales from those of the trust in medication, trust in physician, susceptibility, and chance control subscales. In comparison analyses, the differences in mean total scores between individuals with and without psychoses were not significant. No significant association was found between the ICS and psychopathology. However, both the total and six out of seven subscales of the ICS-T showed a significant connection with compliance. Conclusions In light of these findings, we believe that the ICS-T is a valid and reliable instrument for the assessment of illness concepts in research and clinical settings.