Psychometric Evaluation of Hill-Bone Medication Adherence Subscale

ABSTRACT

PURPOSE: Medication adherence is an essential part of the management and control of high blood pressure (HBP). Although the Hill-Bone Medication Adherence (HBMA) scale is one of the most frequently used instruments for measuring HBP medication adherence, the psychometric properties of the scale have never been tested among Korean Americans, a population that experiences a disproportionately high prevalence of HBP. Therefore, the objective of this study is to validate a Korean version of the HBMA subscale (HBMA-K). METHOD: We used two, independent samples of Korean Americans (KAs) (combined n = 525) who participated in community-based intervention trials for HBP control. To develop the HBMA-K, the original scale was translated into Korean and then back translated into English. Reliability was assessed by calculating the Cronbach's alpha. Exploratory factor analysis (EFA) was done to assess construct validity. We also calculated the Pearson's correlation coefficients between the scale and theoretically driven variables such as blood pressure, knowledge, and HBP belief to test concurrent validity. RESULTS: The EFA revealed a one-factor solution with eight items, explaining 35.4% of the variance. Cronbach's alpha was .80. The 8-item HBMA-K scale was significantly associated with systolic blood pressure (BP) (r = .18, p < .01), diastolic BP (r = .24, p < .01), HBP knowledge (r = -.13, p < .01), and HBP belief score (r = -.18, p < .05). CONCLUSIONS: The 8-item HBMA-K scale is a valid and reliable instrument for measuring medication adherence among KAs with HBP. It can be easily administered at community and clinical settings to screen hypertensive patients with low medication adherence.