Frequency of postoperative delirium and its risk factors in patients with schizophrenia spectrum disorders: a retrospective cohort study

Patients with schizophrenia spectrum disorders (SSDs) have a high risk of physical illnesses that require surgery. Postoperative delirium (POD) is a common complication in patients with SSDs, often requiring psychiatric expertise for management. This study aimed to investigate the incidence and risk factors for POD in patients with SSDs undergoing surgery. A retrospective study was conducted at three tertiary hospitals in Japan, including 200 patients with SSDs who underwent surgery between April 2017 and March 2022. Patients admitted due to psychiatric crises were excluded. Data on demographics, psychiatric history, surgical details, and POD development were collected. Statistical analysis included chi-squared tests and logistic regression to identify risk factors. POD occurred in 10.5% of patients with SSDs, with only one requiring psychiatric ward admission. Most patients had schizophrenia (90.5%), and the mean age was 57.4 years. Significant risk factors for POD included age ≥ 65 years (adjusted odds ratio: 3.25) and smoking before admission (adjusted odds ratio: 2.97). Antipsychotic medication use or dose was not associated with POD. Most POD cases were managed with psychotropic drug adjustments, suggesting that patients with SSDs can be treated at general hospitals if psychiatric expertise is available.