Insight and medication adherence in schizophrenia: An analysis of the CATIE trial

Adherence to antipsychotic medication is critical for the treatment of patients with schizophrenia. Impaired insight into illness is one of the principal drivers of medication nonadherence, which contributes to negative clinical outcomes. The aims of this study were to examine the relationships between impaired insight and (1) rates of antipsychotic medication nonadherence, and (2) time to medication nonadherence using data from the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) study. Insight was assessed using the Positive and Negative Syndrome Scale (PANSS) item G12 (lack of judgment and insight). Patients were divided into 3 groups based on their degree of insight impairment, i.e. no impairment (PANSS G12 = 1), minimal impairment (PANSS G12 = 2-3), and moderate-to-severe insight impairment (PANSS G12 ≥ 4). Medication nonadherence was defined as taking less than 80% of monthly pill counts. Kaplan-Meier survival and Cox regression analyses were performed to examine differences in time to medication nonadherence between insight groups. There were significant differences between insight groups in the percentage of nonadherent patients at 6 months (χ²(2) = 8.80, p = 0.012) and 18 months (χ²(2) = 10.04, p = 0.007) after study initiation. Moderate-to-severe insight impairment was associated with earlier nonadherence compared to minimal (χ² = 4.70, p = 0.030) or no impairment (χ² = 11.92, p = 0.001). The association remained significant after adjustment for illness severity, substance use, attitudes toward medication, cognition, level of hostility, and depression. The results of this study indicate a strong link between impaired insight and antipsychotic medication nonadherence. Interventions to enhance insight early during treatment may help improve medication adherence, and in turn, long-term clinical and functional outcomes in patients with schizophrenia. This article is part of the issue entitled 'Special Issue on Antipsychotics'.