Medical, Psychiatric, and Sociodemographic Predictors of Clozapine Initiation at an Academic Medical Center

Abstract

Background and hypothesis: Clozapine is an effective yet underutilized treatment for treatment-resistant schizophrenia spectrum disorders. This study aimed to identify factors affecting clozapine prescribing patterns among patients with treatment-resistant schizophrenia and schizoaffective disorder at an academic medical center.

Study design: This retrospective combined cohort and case-control study examined demographic, socioeconomic, medical and psychiatric characteristics to determine predictors of clozapine initiation. Eligible patients had a diagnosis of schizophrenia or schizoaffective disorder with at least two prior antipsychotic trials and were admitted to a University of Utah inpatient psychiatric facility (1/2014-3/2021). Patients who did and did not receive clozapine during the index hospitalization were compared in cohort and case-control study arms.

Study results: Twelve percent (59/477) of the cohort received clozapine during the index admission. Among the cohort (n = 477), Black patients were twice as likely to receive clozapine than White and Hispanic patients (OR 2.18, 95% CI 1.20-3.97, p = 0.008). In the case-control analysis, patients with a greater number of previous psychiatric admissions (OR 1.14, p = 0.079) and antipsychotic trials (OR 1.40, p = 0.038) had greater odds of receiving clozapine. Homelessness was identified as a predictor against clozapine use (OR 2.77, p = 0.014).

Conclusions: This is the first study to identify homelessness as a predictor against clozapine use, which raises important clinical and ethical considerations. Our findings also add to the literature on clozapine prescribing discrepancies among ethnic-minority patients. Overall, clozapine remains underutilized as the gold-standard treatment for treatment-resistant schizophrenia-spectrum disorders, reinforcing a need to improve evidence-based prescribing.