Are Illness Concepts a Powerful Predictor of Adherence to Prophylactic Treatment in Bipolar Disorder?

Background: Predicting and preventing premature discontinuation of medication would substantially improve prophylactic treatment of bipolar disorder. Patients’ concepts regarding illness proved to have an impact on noncompliance in a retrospective study of patients with affective or schizoaffective illness treated with lithium. The present study is the first to prospectively investigate the influence of illness concepts on adherence of bipolar patients to different medications.

Method: 171 bipolar patients (DSM-IV) were randomly assigned to receive either lithium (N = 86) or carbamazepine (N = 85) and observed for a maintenance period of 2.5 years (Multicenter Study of Affective and Schizoaffective Psychoses). The total score and 7 dimensions of illness concepts and treatment expectations of the Illness Concept Scale (ICS) were calculated for 141 patients with completed questionnaires and used to predict time to dropout (Cox regression). Analyses were corroborated by further multivariate analyses with sex, age, and premorbid personality as covariates.

Results: With lithium treatment, but not carbamazepine treatment, the total ICS score at study entry was associated with a longer time to study dropout (p = .001 and p = .224, respectively). The relevant ICS subscales affecting time to dropout in patients treated with lithium were trust in medication, trust in the treating physician, and absence of negative treatment expectations. Multivariate analyses suggested that the impact of these variables on adherence to lithium was largely independent of sociodemographic, clinical, and psychological variables. Our data indicate that the stronger impact of illness concepts with lithium as compared with carbamazepine treatment might be related to the drugs’ different side effect profiles.

Conclusion: As trust in drug treatment and trust in the treating physician had a clear impact on adherence to prophylactic lithium, patients’ illness concepts and treatment expectations might be promising targets for psychoeducation and psychotherapy in the treatment of bipolar disorder.