Factors associated with medication non-adherence in patients suffering from schizophrenia: a cross-sectional study in a universal coverage health-care system

Objective: To quantify the factors associated with non-adherence to medication among stable patients suffering from schizophrenia in the context of universal access to care. Methods: This naturalistic, multicentric study was conducted in 15 French public hospitals in a region of south-eastern France during a 1 week period in 2008. All consecutive outpatients with stable schizophrenia were recruited. Adherence was assessed with the 10-item Drug Attitude Inventory (DAI). Measures included socio-demographic characteristics, clinical characteristics, insight using the Scale to assess Unawareness of Mental Disease (SUMD), and therapeutic alliance using the Patient Session Questionnaire (PSQ). Regression models were used to identify the risk factors associated with non-adherence. Results: The study included 291 patients, 30% of whom were considered to be non-adherent. Non-adherence increased with duration of untreated psychosis (DUP) (OR = 1.12, 95%CI = 1.03-1.22), lack of insight only for the dimension 'effect of medication' (OR = 3.23, 95%CI = 1.05-9.89), and a low level of therapeutic alliance (OR = 0.45, 95%CI = 0.32-0.64). Individuals prescribed atypical antipsychotic drugs were more likely to be adherent than those prescribed typical antipsychotics (OR = 0.37, 95%CI = 0.13-1.0). Conclusions: DUP, prescription of typical antipsychotics, therapeutic alliance and insight were the most important features associated with non-adherence. This study also suggests that economic factors such as the service delivery system should not be neglected in public strategies aimed at addressing problems of non-adherence in non-universal coverage health systems.