Antipsychotic nonadherence measured by electronic adherence monitoring in stabilized chronic schizophrenia: Clinical implications

Background: There have been a number of studies investigating antipsychotic adherence measured by electronic adherence monitoring (EAM) in patients with schizophrenia. However, no study has looked at overall adherence and both baseline and endpoint illness/symptom severity. Methods: We performed a secondary analysis of our previous study to examine antipsychotic adherence, as measured by EAM, and illness/symptom severity at baseline and endpoint in patients with schizophrenia. Adherence rates were defined as the proportion of adherent days over 3 months. Adherent days were defined as the subject having taken the medication at the prescribed time, with 2 tolerance margins operationally defined i.e., ±3 h and ±12 h. In addition, a dichotomous version of adherence was defined i.e., if he/she was adherent greater than 80% of the days. Illness severity and symptom severity were assessed using the Brief Psychiatric Rating Scale (BPRS) total score and the Clinical Global Impression – Severity of illness (CGI-S) scale score, respectively. Results: A total of 111 patients were enrolled in the study. Neither continuous or dichotomous adherence rates were significantly associated with baseline or endpoint illness/symptom severity (all Ps ≥ 0.05). The results remained unchanged when adjusting for clinico-demographic characteristics. Conclusion: Antipsychotic adherence, as measured by EAM, was not associated with illness/symptom severity at baseline and endpoint in patients with chronic schizophrenia, whose clinical status and adherence pattern were stabilized. This suggests that individuals may be able to achieve clinical stability in the face of maintenance antipsychotic treatment despite variations in adherence.