Substance use disorder, psychiatric illness, and suicide risk among hospitalized incarcerated adults: A retrospective study using National Inpatient Sample (NIS) database

BACKGROUND AND OBJECTIVES: Hospitalization offers a limited but important opportunity to address medical and psychiatric needs among incarcerated adults, who have high burdens of substance use disorder (SUD), mental illness, and suicide-related risk. National comparative data by SUD status remain sparse. METHODS: We conducted a retrospective study using the National Inpatient Sample (2016-2021) of hospitalized adults with ICD-10 codes indicating incarceration to evaluate the association between SUD and psychiatric comorbidity, suicidality, and hospitalization outcomes in the United States. RESULTS: Among 92,715 (N) hospitalized incarcerated adults, 40.4% had SUD. Patients with SUD were younger (40.7 ± 11.4 vs. 48.4 ± 13.9 years) and more frequently female (22.2% vs. 12.6%). SUD was strongly associated with suicidal ideation (75.4% vs. 38.6%; adjusted odds ratio [aOR] 3.73; p < .001). Multivariable analyses demonstrated higher odds of major depressive disorder (aOR 1.43), schizophrenia-spectrum disorders (aOR 1.61), bipolar disorder (aOR 1.66), anxiety disorders (aOR 2.07), trauma-related disorders (aOR 1.90), and personality disorders (aOR 1.63) (all p < .001). Despite this, SUD was associated with lower in-hospital mortality and total charges, with no significant difference in length of stay. DISCUSSION AND CONCLUSIONS: SUD is highly prevalent and independently associated with increased psychiatric burden and suicide-related risk in hospitalized incarcerated adults. These findings support prioritizing integrated inpatient approaches to address co-occurring addiction and mental health conditions in this vulnerable population. SCIENTIFIC SIGNIFICANCE: These findings identify SUD as a significant factor associated with psychiatric morbidity and suicidality among incarcerated patients, highlighting hospitalization as an important opportunity for integrated screening, assessment, and care delivery.