Risk factors for non-adherence to antidepressant treatment in patients with mood disorders

Adherence to antidepressant therapy by patients with depressive disorders is essential not only to achieve a positive patient outcome but also to prevent a relapse. The aim of this study was to identify potential modelling factors influencing adherence to antidepressant treatment by patients with mood disorders in the community mental health care setting

A total of 160 consecutive psychiatric outpatients attending two Community Mental Health Centres on Tenerife Island between September 2011 and May 2012 were asked to participate in the study; of these, 145 accepted. The Morisky self-report scale was used to assess adherence. The potential predictors examined included socio-demographic, clinical and therapeutic variables. The Clinical Global Impression-Severity and -Improvement scales and the Beck Depression Inventory were used for clinical assessment. Drug treatment side-effects were assessed using the "Self-report Antidepressant Side-Effect Checklist." All participants were also asked to complete the "Drug Attitude Inventory" (DAI), "Beliefs about Medicine Questionnaire" (BMQ), and "Leeds Attitude towards concordance Scale". Discriminant analyses were performed to predict non-adherence.

There was no clear correlation between adherence and the socio-demographic variables examined, but adherence was related to a positive attitude of the patients towards his/her treatment (DAI) and low scores in the BMQ-Harm and -Concern subscales. Non-adherence was also related to an increasing severity of depression and to the presence and severity of side-effects.

Among our study cohort, the profiles of adherent patients to antidepressant treatment were more closely associated with each patient's attitudes and beliefs than to objective socio-demographic variables. The severity of depression played a relevant role in adherence, but whether this role is direct or an interaction with several concurrent factors is not yet clear. Side-effects were also closely related to adherence, as conditioned by frequent polypharmacy.