title: The ARMS-D out performs the SDSCA, but both are reliable, valid, and predict glycemic control.
abstract: OBJECTIVE
  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 HbA1C 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 HbA1C.
  
  
  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 (α=0.86), maintained its factor structure, and had convergent validity with the SDSCA-MS (rho=-0.52, p<0.001). Both the ARMS-D (β=0.16, p<0.01) and the SDSCA-MS (β=-0.12, p<0.05) independently predicted HbA1C 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 HbA1C 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.
authors.affiliation: Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37204, United States.
authors.forename: Lindsay S
authors.initials: LS
authors.lastname: Mayberry
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Gonzalez
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Wallston
authors.forename: Sunil
authors.initials: S
authors.lastname: Kripalani
authors.forename: Chandra Y
authors.initials: CY
authors.lastname: Osborn
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy*; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D007328:Insulin / Q000627:therapeutic use; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D012648:Self Care; D057566:Self Report; D011795:Surveys and Questionnaires
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D007328:Insulin
keywords: Diabetes; Glycemic control; Insulin; Medication adherence; Validity