Adherence to depot versus oral antipsychotic medication in schizophrenic patients during the long-term therapy

Abstract

There is a high rate of schizophrenic patients who do not adhere to their prescribed therapy, despite the implementation of antipsychotic long-acting injections and the introduction of atypical antipsychotics. The aim of this study was to investigate the differences in sociodemographic, clinical and medication adherence variables between the two groups of schizophrenic patients on maintenance therapy with depot antipsychotic fluphenazine decanoate and oral antipsychotics only as well as a correlation between the medication adherence and other examined variables. A total of 56 patients of both genders, aged < 60 years, with the diagnosis of schizophrenia (F20) (ICD-10, 1992) clinically stable for at least 6 months were introduced in this cross-sectional study. The patients from the depot group (n = 19) were on classical depot antipsychotic fluphenazine decanoate administering intramuscularly every 4 weeks (with or without oral antipsychotic augmentation) and the patients from the oral group (n = 37) were on oral therapy alone with classical or atypical antipsychotics, either as monotherapy or combined. The Positive and Negative Syndrome Scale (PANSS) was used to assess symptom severity. Item G12 of the PANSS was used to assess insight into the illness. The patients completed the Medical Adherence Rating Scale (MARS) was used to assess adherence to the therapy. A higher MARS score indicates behavior [Medical Adherence Questionnaire (MAQ subscale)] and attitudes toward medication [Drug Attitude Inventory (DAI subscale)] that are more consistent with treatment adherence. The exclusion criteria were determined. The Pearson's chi2 test was used to compare categorical variables, Student's t-test to compare continuous variables and Pearson's correlation to test the correlation significance; p = 0.05. Significant between-group differences in age, illness duration, chlorpromazine equivalents, PANSS score and DAI subscore were found. Item G12 of the PANSS subscore and MARS score correlated significantly negatively. A significant positive correlation between receiving depot antipsychotic and DAI subscore as well as between illness duration and both DAI subscore and MARS score were also found. Schizophrenic patients on classical depot antipsychotic maintenance therapy might present subpopulation of patients with significantly longer illness duration, more favorable medication attitude and outcome in relation to those on oral antipsychotics alone.