Sex Difference in Risk and Protective Factors of State Psychiatric Hospital Readmissions among Non-forensic Psychiatric Patients in the United States in 2020—2023: Discrete-Time Hazard Models Applied To the National Mental Health Client-Level Data

Researchers and policymakers use hospital readmission rates as measures of health care quality and cost. This study used the Mental Health Client-Level Data (MH-CLD) to document hospital readmission rates and determinants of readmission for female and male patients discharged from state psychiatric hospitals across 36 U.S. states and Puerto Rico between 2020 and 2023. The results show that the readmission rate was significantly higher among males than among females at 30 days (7.8% vs. 7.1%) and throughout the 26-week post-discharge observation period. Based on discrete-time hazard models applied to discharge-week panel data constructed from discharge data from 110,353 unique patients, the most important common risk factors for both sexes were being Hispanic, a diagnosis of schizophrenia or other psychotic disorders or bipolar disorder, co-occurring substance use problems, and having a serious mental illness (SMI). However, a diagnosis of depressive disorders increased the likelihood of re-hospitalization only among males and a diagnosis of bipolar disorder increased the likelihood of re-hospitalization more substantially for males than females. Being married was a common protective factor for both sexes, but its effect was significantly greater for males. Other significant sex differences included Black male patients having a higher likelihood of readmission than their White counterparts, but this was not observed among Black female patients. Involuntary admission had opposite effects by sex: it increased the likelihood of readmission for females but decreased it for males. Consideration of the types and length of treatment at hospitals and post-discharge care may provide insight into these sex differences.