Development and evaluation of the psychometric properties of a hypertension self-care questionnaire

BACKGROUND: There are a number of tools to assess self-care in hypertension (HTN), but they do not cover all the dimensions of self-care and do not have a good reliability and validity. This study was conducted to develop and evaluate the psychometric properties of a tool for self-care assessment in HTN. METHODS: This cross-sectional, methodological study was conducted in Isfahan, Iran. An expert panel was held to assess the qualitative face validity of the tool. The content validity ratio (CVR) and content validity index (CVI) were measured. The questionnaire was distributed among 20 patients to measure its internal reliability. After 14 days, it was re-distributed among the same patients, as a measure of external reliability. The questionnaire was completed by 203 patients with HTN and an exploratory factor analysis was performed in order to assess the construct validity of the tool. RESULTS: The items of the self-care tool were confirmed with a CVR ≥ 0.5, Kappa ≥ 0.71, I-CVI = 0.69, and intraclass correlation coefficient (ICC) = 0.952. The factor analysis showed that the 16-item questionnaire has 5 dimensions, including follow-up [3 items; factor loadings (FL) = 0.619 to 0.869, and Cronbach's alpha (α) = 0.737], healthy lifestyle (5 items; FL = 0.709 to 0.846, α = 0.703), promoting qualifications (4 items; FL = 0.610 to 0.791, α = 0.594), medication therapy (2 items; FL = 0.699 and 0.740, α = 0.717), and following recommendations (2 items, FL = 0.577 and 0.744, α = 0.701). These 5 dimensions explained 62.686% of the variance. The Cronbach's alpha coefficient of the final self-care assessment questionnaire was 0.833. CONCLUSION: The developed questionnaire proved to have appropriate psychometric properties for measuring self-care in patients with HTN.