title: Validity of medication adherence self-reports in adults with type 2 diabetes.
abstract: OBJECTIVE
  To assess the validity of self-report measures of diabetes medication adherence and evaluate the effect of depression on the validity of these reports.
  
  
  METHODS
  Adults with type 2 diabetes, treated with oral medications, completed a set of medication adherence self-reports that varied response scales and time frames, were administered structured clinical interviews for depression, and provided blood samples for HbA(1c) as part of a screening for an intervention study. A subsample of participants with HbA(1c) ≥7.0% and clinically significant depression received Medication Event Monitoring System (MEMS) bottle caps to record adherence. Analyses examined relationships between adherence measures and HbA(1c) and, in the subsample, MEMS. Moderated linear regression evaluated whether depression severity modified relationships with HbA(1c).
  
  
  RESULTS
  Participant (n = 170, 57% men, 81% white, mean HbA(1c) 8.3% [SD, 1.7]) adherence self-reports were significantly (r = -0.18 to -0.28; P < 0.03) associated with lower HbA(1c). In the subsample (n = 88), all self-reports were significantly (r = 0.35 to 0.55; P ≤ 0.001) associated with MEMS-measured adherence. Depression significantly moderated the relationship between three of six self-reports and HbA(1c); at high levels of depression, associations with HbA(1c) became nonsignificant.
  
  
  CONCLUSIONS
  Results support the validity of easily administered self-reports for diabetes medication adherence. One-month, percentage-based ratings of adherence had the strongest associations with MEMS and HbA(1c); those requiring the report of missed doses had weaker associations. One-week self-ratings and measures that require respondents to record the number of missed doses appear to be vulnerable to bias from depression severity.
authors.affiliation: Ferkauf Graduate School of Psychology, Yeshiva University, Bronx, New York, USA. jeffrey.gonzalez@einstein.yu.edu
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Gonzalez
authors.forename: Havah E
authors.initials: HE
authors.lastname: Schneider
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Wexler
authors.forename: Christina
authors.initials: C
authors.lastname: Psaros
authors.forename: Linda M
authors.initials: LM
authors.lastname: Delahanty
authors.forename: Enrico
authors.initials: E
authors.lastname: Cagliero
authors.forename: Steven A
authors.initials: SA
authors.lastname: Safren
mesh_terms: D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000378:metabolism; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged
chemical_list: D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents