Adaptation and Psychometric Validation of the EMPOWER-SUSTAIN Usability Questionnaire (E-SUQ) among Patients with Metabolic Syndrome in Primary Care

Self-management support is one of the most important components of the Chronic Care Model (CCM). The EMPOWER-SUSTAIN Global Cardiovascular Risks Self-Management Booklet© was developed for patients with Metabolic Syndrome (MetS), inspired by the CCM. Assessing usability of a self-management tool is important in chronic disease management. However, there was no available instrument to assess usability of a self-management booklet, as most instruments were developed to assess usability of mobile application. Therefore, this study aimed to adapt Skala Kebolehgunaan Aplikasi Mudah Alih (SKAMA) into the EMPOWER-SUSTAIN Usability Questionnaire (E-SUQ) and to determine its validity and reliability in assessing usability of a self-management booklet. A cross-sectional validation study was conducted among patients with MetS attending a university primary care clinic in Selangor, Malaysia. Content validation, adaptation and face validation of E-SUQ were performed according to recommended guidelines. It underwent two rounds of content validation as major revision was required for item 5. Subsequently, the revised E-SUQ was face-validated by 10 participants. Psychometric evaluation was conducted using principal component analysis with varimax rotation to determine the underlying structure of E-SUQ. Internal consistency reliability was assessed using Cronbach's α coefficient and the test-retest reliability was assessed using intraclass correlation coefficient (ICC (2,k)). A total of 205 patients participated in the study. The item-level content-validity-index (I-CVI) for item 5 improved from 0.57 to 1.0 after the second round of content validation. The final S-CVI/Ave value for ESUQ was >0.90. The item-level face-validity-index (I-FVI) ranged between 0.9 and 1.0. Kaiser-Meyer-Olkin value of 0.871 and Bartlett's test of sphericity p-value of <0.05 indicated good sample adequacy for factor analysis. Two factors with eigenvalues of >1 were extracted according to the Kaiser's Criteria. The two extracted factors explained 60.6% of the cumulative percentage of variance. The elbow of the scree plot occurred between the second and third component, suggesting two factors to be retained. The two factors were consistent with "Positive" and "Negative" tone model. The overall Cronbach's α coefficient was 0.77, indicating good internal reliability. The overall ICC was 0.85, indicating good reproducibility. The E-SUQ is shown to be valid, reliable and stable to measure the usability of a self-management booklet among patients with MetS in a university primary care clinic in Malaysia.