The Validity of Medication Adherence Self-Reports in AdultsWith Type 2 Diabetes

Abstract

OBJECTIVEdTo assess the validity of self-report measures of diabetes medication adherence and evaluate the effect of depression on the validity of these reports. RESEARCH DESIGN ANDMETHODSdAdults 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 HbA1c as part of a screening for an intervention study. A subsample of par-ticipants with HbA1c $7.0 % and clinically significant depression received Medication Event Monitoring System (MEMS) bottle caps to record adherence. Analyses examined relationships between adherence measures and HbA1c and, in the subsample, MEMS. Moderated linear re-gression evaluated whether depression severity modified relationships with HbA1c. RESULTSdParticipants ’ (n = 170, 57 % men, 81 % white, mean HbA1c = 8.3 % [SD, 1.7]) adherence self-reports were significantly (r =20.18 to 20.28; P, 0.03) associated with lower HbA1c. 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 relation-ship between three of six self-reports and HbA1c; at high levels of depression, associations wit