The ARMS-D out performs the SDSCA, but both are reliable, valid, and predict glycemic control

Aims: The Adherence to Refills and Medications Scale (ARMS) has been associated with objective measures of adherence and may address limitations of existing self-report measures of diabetes medication adherence. We modified the ARMS to specify adherence to diabetes medicines (ARMS-D), examined its psychometric properties, and compared its predictive validity with HbA(1C) against the most widely used self-report measure of diabetes medication adherence, the Summary of Diabetes Self-Care Activities medications subscale (SDSCA-MS). We also examined measurement differences by age (<65 vs. >= 65 years) and insulin status. Methods: We administered self-report measures to 314 adult outpatients prescribed medications for type 2 diabetes and collected point-of-care HbA(1C). Results: One of the 12-item ARMS-D items was identified as less relevant to adherence to diabetes medications and removed. The 11-item ARMS-D had good internal consistency reliability (alpha = 0.86), maintained its factor structure, and had convergent validity with the SDSCA-MS (rho = -0.52, p < 0.001). Both the ARMS-D (beta = 0.16, p < 0.01) and the SDSCA-MS (beta = -0.12, p < 0.05) independently predicted HbA(1C) after adjusting for covariates, but this association did not hold among participants >= 65 years in subgroup analyses. There were no differences in ARMS-D or SDSCA-MS scores by insulin status, but participants on insulin reported more problems with adherence on two ARMS-D items (i.e., feeling sick and medicine costs). Conclusions: The ARMS-D is a reliable and valid measure of diabetes medication adherence, and is more predictive of HbA(1C) than the SDSCA-MS, but takes more time to administer. The ARMS-D also identifies barriers to adherence, which may be useful in research and clinical practice. (C) 2013 Elsevier Ireland Ltd. All rights reserved.