Development and psychometric validation for evaluating written medicine information in Thailand: The Consumer Information Rating Form

Objective To translate and validate the consumer information rating form (CIRF) for use in Thai populations. Design The development of the CIRF was carried out in two phases: translation process and cognitive interview, and psychometric testing. Setting A university hospital and a tertiary hospital in northeast Thailand. Participants 150 outpatients from medicine department: 30 for phase 1 and 120 patients for phase 2 study. Methods The CIRF was translated with cultural adaptation into Thai using cognitive interview technique in a sample of outpatients. A larger sample of outpatients then completed the CIRF in relation to either a package insert (PI) or a patient information leaflet (PIL) for one of three medicines: atorvastatin, celecoxib and metformin. Construct validity was assessed using principal component analysis (PCA) and internal consistency using Cronbach's alpha coefficient. Known group validity was assessed by comparing mean consumers' ratings for PIs and PILs. Results Thirty participants engaged in the cognitive interview and 120 participants completed the CIRF. The PCA found the 17 items of the CIRF were extracted into three factors: comprehensibility, utility and design quality scales, mirroring the original. Cronbach's alpha for the overall scale (0.904) indicated good internal consistency. Known-group validity demonstrated significant differences in consumers' rating between PIs and PILs for almost all items (p<0.001). Conclusion Thai version of CIRF had acceptable validity and reliability for Thai consumers' ratings of written medicine information. The CIRF could be of practical use in the process of developing medicine information to ensure consumers' comprehension and their usefulness.