Depressive residual symptoms are associated with lower adherence to medication in bipolar patients without substance use disorder: results from the FACE-BD cohort.

BACKGROUND: Poor adherence to medication is frequent in Bipolar Disorder (BD). It is associated with illness severity and increases total medical cost. Several factors are associated with poor adherence but previous studies included heterogeneous cohorts of patients with and without current mood episode, with and without SUD.
METHODS: We conducted a cross-sectional study, based on the Fondamental Advanced Centers of Expertise in Bipolar Disorders. 382 patients diagnosed with BD (type I, II or NOS) according to DSM-IV, with partial or complete remission and without comorbid SUD, were included. All patients had a large standardized clinical evaluation with structured interview and self reports. Side effects were evaluated with Patient Rated Inventory of Side Effects (PRISE). Adherence behavior was measured by a self reported scale, Medication Adherence Rating Scale (MARS). Univariate analyses and linear regression models were undertaken to determine factors associated with adherence.
RESULTS: Residual depressive symptoms (β=-0.155, p=0.004), and side effects (β=-0.142, p=0.008) were the main factors associated with adherence behavior in linear regression model. We found no association with residual manic symptoms, age at assessment, marital status, number of past mood episodes as well as past psychotic symptoms. LIMITATION: We used no other assessment than self-rating scale for adherence behavior evaluation. We had no information concerning treatment regimen and patient/family knowledge about BD.
CONCLUSIONS: Adherence behavior in bipolar patients appears to be mainly influenced by the presence of residual depressive symptoms in patients without SUD. Improvement in diagnosis and pharmacotherapy of residual depressive symptoms has to be kept in mind to face low adherence to medication.