Factors Associated with All-Cause Mortality in a Western State Prison System, 1999-2020.

Introduction: Incarceration is linked to mortality, yet specific factors associated with death during imprisonment remain poorly understood, limiting efforts to identify vulnerable populations and develop effective prevention strategies in carceral settings.

Methods: Administrative records were analyzed from 91,979 adults who served any portion of their sentence in a Western US state prison system between 1999 and 2020. Complementary log-log regression was used to identify demographic, criminal history, institutional, and behavioral health-related factors associated with all-cause mortality in prison.

Results: Of incarcerated individuals (mean age 35.83 years at admission; 86.3% male), 839 (0.91%) died in prison. Self-harm incidents (HR 15.19; 95% CI 10.50-21.98) and sentences of 21+ years (HR 16.84; 95% CI 10.49-27.03 vs. ≤1 year) were most strongly associated with mortality. Variety of correctional programs completed was a protective factor (HR 0.78; 95% CI 0.74-0.82), and foreign-born status (HR 0.41; 95% CI 0.26-0.65), Black race (HR 0.73; 95% CI 0.59-0.91 vs. White), and violent infractions (HR 0.91; 95% CI 0.88-0.95) had inverse associations with mortality. Mortality risk increased substantially with age, with individuals aged 55+ years at admission having over 11 times the risk of death compared to those aged 24 and under (HR 11.79; 95% CI 8.75-15.88). Male sex, prior incarcerations, higher custody levels, drug infractions, mental health needs, academic needs, and criminogenic needs were also associated with increased mortality risk.

Conclusions: This study identified new risk factors for mortality during imprisonment. The findings highlight directions for future research and actionable intervention points for reducing mortality in incarcerated populations.