Pneumonia Risk, Antipsychotic Dosing, and Anticholinergic Burden in Schizophrenia

IMPORTANCE: Antipsychotic drugs (particularly clozapine) have been associated with pneumonia in observational studies. Despite studies of the associations between antipsychotic use and incident pneumonia, it remains unclear to what degree antipsychotic use is associated with increased risk of pneumonia, whether dose-response associations exist, and what agents are specifically associated with incident pneumonia. OBJECTIVE: To estimate pneumonia risk associated with specific antipsychotics and examine whether polytherapy, dosing, and receptor binding properties are associated with pneumonia in patients with schizophrenia. DESIGN, SETTING, AND PARTICIPANTS: This cohort study identified patients with schizophrenia or schizoaffective disorder (hereafter, schizophrenia) aged 16 years or older from nationwide Finnish registers from 1972 to 2014. Data on diagnoses, inpatient care, and specialized outpatient care were obtained from the Hospital Discharge Register. Information on outpatient medication dispensing was obtained from the Prescription Register. Study follow-up was from 1996 to 2017. Data were analyzed from November 4, 2022, to December 5, 2023. EXPOSURES: Use of specific antipsychotic monotherapies; antipsychotics modeled by dosage as low (