RESUMEN
BACKGROUND: To transfer a paper-version Chinese and Western medication adherence scale for CKD into an electronic scale, and evaluate its validity, internal consistency and clinical implementation, and assess whether the transition is feasible in clinic. METHODS: We built an e-version Chinese and Western medication adherence scale based on the Wen-JuanXing platform. CKD subjects' responses were applied to test the scale's validity and internal consistency. We retested some of the participants two weeks later randomly. We also tested the clinical application. RESULTS: Of the 434 recruited patients, 228 responded. In exploratory factor analysis (EFA), the Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy = 0.8 and Bartlett's approx. Chi-Square = 1340.0 (df = 105, p < 0.001). We extracted four common factors which could explain 61.47% of the variance. However, Item 15 "Have you changed a traditional Chinese medicine prescription yourself within the past month?" had factor loading = 0.3 and measure of sampling adequacy (MSA) = 0.5, meaning we could not enter it into the factor analysis. The internal consistency reliability for medication adherence was 0.9, with a Guttman split-half coefficient = 0.5 and a Spearman-Brown coefficient = 0.6. Cronbach's α was 0.9, 0.4 and 0.5 for the knowledge, belief and behavior domains, respectively. The correlation coefficient r of the test-retest reliability was -0.8 and was -0.8, 0.4, -0.3 in the knowledge, belief and behavior domains, respectively. Patients with comorbidities were more likely to respond. We detected no other significant differences in the clinical profiles between respondents and non-respondents. CONCLUSION: The e-version Chinese and Western medication adherence scales have undesirable construct validity and internal consistency. Thus, caution is needed in transitioning the paper-version scale into an e-version.
RESUMEN
PURPOSE: This study aimed to simplify the version-1 Chinese and Western medication adherence scale for patients with chronic kidney disease (CKD) to a version-2 scale using item response theory (IRT) analyses, and to further evaluate the performance of the version-2 scale. MATERIALS AND METHODS: Firstly, we refined the version-1 scale using IRT analyses to examine the discrimination parameter (a), difficulty parameter (b) and maximum information function peak (Imax). The final scale refinement from version-1 to version-2 scale was also decided upon clinical considerations. Secondly, we analyzed the reliability and validity of version-2 scale using classical test theory (CTT), as well as difficulty, discrimination and Imax of version-1 and version-2 scale using IRT in order to conduct scale evaluation. RESULTS: For scale refinement, the 26-item version-1 scale was reduced to a 15-item version-2 scale after IRT analyses. For scale evaluation using CTT, internal consistency reliability (total Cronbach α = 0.842) and test-rest reliability (r = 0.909) of version-2 scale were desirable. Content validity indicated 3 components of knowledge, belief and behaviors. We found meritorious construct validity with 3 detected components as the same construct of medication knowledge (items 1-9), medication behavior (items 13-15), and medication belief (items 10-12) based upon exploratory factor analysis. The correlation between the version-2 scale and Morisky, Green and Levine scale (MGL scale) was weak (Pearson coefficient = 0.349). For scale evaluation with IRT, the findings showed enhanced discrimination and decreased difficulty of most retained items (items 1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15), decreased Imax of items 1, 2, 3, 4, 6, 11, 14, as well as increased Imax of items 5, 7, 8, 9, 10, 12, 13, 14, 15 in the version-2 scale than in the version-1 scale. CONCLUSION: The original Chinese and Western medication adherence scale was refined to a 15-item version-2 scale after IRT analyses. The scale evaluation using CTT and IRT showed the version-2 scale had the desirable reliability, validity, discrimination, difficulty, and information providedoverall. Therefore, the version-2 scale is clinically feasible to assess the medication adherence of CKD patients.