Adherence to antipsychotic drug treatment in early-episode schizophrenia: A six-month naturalistic follow-up study

Background: The Health Belief Model states that medication adherence is primarily determined by beliefs (i.e., perceptions of: adherence costs and benefits, susceptibility, and outcome severity), yet little is known regarding the model's longitudinal utility. Aims: To examine the longitudinal utility of the Health Belief Model in explaining non-adherence with antipsychotic medication in clinical settings in early-episode schizophrenia. Method: Participants (n = 112) with a DSM-IV diagnosis of schizophrenia (n = 84, 75%) or schizoaffective disorder (n = 28, 25%) participated in a four wave six month study. Participants were assessed on adherence (Visual Analog Scale for Assessing Treatment Adherence), symptom severity indices, the Drug Attitudes Inventory, and extrapyramidal side-effects. Results: Unlike non/partially adherent participants, adherent participants showed statistically significantly (p<.05) more: insight into illness, awareness of the need for medication, positive perceptions of trust in the doctor-patient therapeutic alliance, perceived family involvement in pharmacological treatment, positive attitudes towards medication in the family and fewer adverse events. Adherence rates at endpoint did not differ between typical, atypical and mixed antipsychotic medication groups. Structural equation modeling showed that over 6 months symptom severity, awareness for the need of medication and attitudes to medication predicted adherence. Awareness of the need of medication, awareness of social consequences, participant's perceived trust in physician and the severity of negative symptoms all predicted attitudes to medication that in turn predicted adherence. Conclusions: The current results partly support the adherence Health Belief Model, and emphasize the role of attitudes toward medication as a predictor of adherence. (C) 2011 Elsevier B.V. All rights reserved.