Depression affects adherence measurement but not the effectiveness of an adherence intervention in heart failure patients

Abstract

Objectives: To assess the influence of depressive symptoms on adherence with heart failure medications and to determine whether the effect of a pharmacy-based intervention to improve heart failure medication adherence is modified by depressive symptoms.

Design: Secondary analysis of data from a randomized controlled trial.

Setting: University-affiliated ambulatory care practice.

Patients: Patients 50 years or older with congestive heart failure randomly assigned to usual care (n = 192) or intervention (n = 122).

Intervention: Pharmacist-provided intervention to improve heart failure medication adherence.

Main outcome measures: Medication adherence was measured via patient self-report and using electronic prescription lids; depressive symptoms were measured using the Geriatric Depression Scale. General linear models examined the main effect of depressive symptoms on medication adherence and whether depressive symptoms modified the effectiveness of the intervention.

Results: At baseline, 37% (n = 117) of participants screened positive for depression. In the usual care group, mean adjusted self-reported adherence was 75% for depressed participants and 81% for nondepressed participants (P = 0.04); mean adjusted adherence measured electronically was 71% for depressed participants and 69% for nondepressed participants (P = 0.65). INTERVENTION effectiveness did not differ for depressed compared with nondepressed participants.

Conclusion: The effectiveness of a pharmacy-based intervention to improve adherence does not appear to be influenced by depression. However, the method used to measure adherence (electronically measured versus self-reported) influences the interpretation of the relationship between depression and heart failure medication adherence.