title: The agreement of patient-reported versus observed medication adherence in type 2 diabetes mellitus (T2DM).
abstract: OBJECTIVE
  Medication adherence in type 2 diabetes mellitus (T2DM) improves glycemic control and is associated with reduced adverse clinical events, and accurately assessing adherence assessment is important. We aimed to determine agreement between two commonly used adherence measures-the self-reported Morisky Medication Adherence Scale (MMAS) and direct observation of medication use by nurse practitioners (NPs) during home visits-and determine the relationship between each measure and glycated hemoglobin (HbA1c).
  
  
  METHODS
  We evaluated agreement between adherence measures in the Southeastern Diabetes Initiative (SEDI) prospective clinical intervention home visit cohort, which included high-risk patients (n=430) in 4 SEDI-participating counties. The mean age was 58.7 (SD 11.6) years. The majority were white (n=210, 48.8%), female (n=236, 54.9%), living with a partner (n=316, 74.5%), and insured by Medicare/Medicaid (n=361, 84.0%). Medication adherence was dichotomized to 'adherent' or 'not adherent' using established cut-points. Inter-rater agreement was evaluated using Cohen's κ coefficient. Relationships among adherence measures and HbA1c were evaluated using the Wilcoxon rank-sum test and c-statistics.
  
  
  RESULTS
  Fewer patients (n=261, 61%) were considered adherent by self-reported MMAS score versus the NP-observed score (n=338; 79%). Inter-rater agreement between the two adherence measures was fair (κ=0.24; 95% CI 0.15 to 0.33; p<0.0001). Higher adherence was significantly associated with lower HbA1c levels for both measures, yet discrimination was weak (c-statistic=0.6).
  
  
  CONCLUSIONS
  Agreement between self-reported versus directly observed medication adherence was lower than expected. Though scores for both adherence measures were significantly associated with HbA1c, neither discriminated well for discrete levels of HbA1c.
authors.affiliation: Department of Advanced Clinical Practice , Duke University Health System , Durham, North Carolina , USA.
authors.forename: Katherine
authors.initials: K
authors.lastname: Kelly
authors.affiliation: Duke Clinical Research Institute , Durham, North Carolina , USA.
authors.forename: Maria V
authors.initials: MV
authors.lastname: Grau-Sepulveda
authors.affiliation: Duke Clinical Research Institute , Durham, North Carolina , USA.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Goldstein
authors.affiliation: Department of Medicine , Duke University School of Medicine , Durham, North Carolina , USA.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Spratt
authors.affiliation: Duke Clinical Research Institute , Durham, North Carolina , USA.
authors.forename: Anne
authors.initials: A
authors.lastname: Wolfley
authors.affiliation: Williamson Memorial Hospital Diabetes Management Clinic , Williamson, West Virginia , USA.
authors.forename: Vicki
authors.initials: V
authors.lastname: Hatfield
authors.affiliation: Department of Community Health , Cabarrus Health Alliance , Kannapolis, North Carolina , USA.
authors.forename: Monica
authors.initials: M
authors.lastname: Murphy
authors.affiliation: University of Mississippi Medical Center, School of Health Related Professions , Jackson, Mississippi , USA.
authors.forename: Ellen
authors.initials: E
authors.lastname: Jones
authors.affiliation: Duke University Health System, School of Nursing , Durham, North Carolina , USA.
authors.forename: Bradi B
authors.initials: BB
authors.lastname: Granger
keywords: Adherence to Medications; Self-Reported Regimen Adherence