(P-507) Suicide Risk in Schizophrenia Across the Lifespan

Background: Although adults with schizophrenia have a significantly increased risk of suicide, sample size limitations of previous research have hindered characterizations of suicide risk across the lifespan.

Objectives: To describe suicide mortality rates and correlates among adults with schizophrenia across the lifespan as well as standardized mortality ratios (SMR) compared to the US general population.

Methods: Setting: Retrospective cohort study among schizophrenia patients (ICD-9CM: 295.X or ICD-10: F20.X, F25.X) with US Medicare fee-for-service and prescription drug coverage (2007-2016).
Exposures: Socio-demographics, clinical characteristics (e.g., depression, anxiety, chronic pain), and measures of acute care service utilization (e.g.,mental health inpatient admission).
Study outcome: Death by suicide, defined as a recorded death with ICD-10 codes X60-X84 or Y87.0 as the underlying cause of death in the linked National Death Index file.
Analysis: For each age group (18-34, 35-44, 45-54, 55-64 and ≥65 years), suicide mortality rates per 100,000 person-years and adjusted hazard ratios (aHR) with 95% confidence intervals (CI) of suicide were determined (the latter from multivariate Cox models, with demographic, clinical, and utilization characteristics as independent variables, and time until suicide as outcome variable). In addition, suicide SMRs were estimated for the overall schizophrenia cohort and each age cohort standardized to the general population with respect to age, sex, and race/ethnicity.

Results: The cohort included 668,836 adults with schizophrenia, 2,997,308 years of follow-up, and 2,218 suicide deaths. Overall, the suicide rate per 100,000 person-years for adults with schizophrenia was 74.0 (SMR 4.5, 95%CI 4.4-4.7). The suicide rate declined with age from 142.0 (SMR 10.2, 95%CI 9.3-11.2) for patients aged 18-34 years to 24.01 (SMR 1.5, 95%CI 1.3-1.8) for patients aged ≥65 years. The corresponding declines in rates of suicide per 100,000 person-years were from 153.80 (18-34 years) to 34.17 (≥65 years) for men and from 115.70 (18-34 years) to 18.66 (≥65 years) for women. In the highest risk age group (18-34 years), suicide risk was associated with suicide attempt or self-injury (aHR 2.57, 95%CI 1.83-3.63), suicidal ideation (aHR 1.54, 95%CI 1.16-2.04), and comorbid drug use disorders (aHR 1.54, 95%CI 1.17-1.88), but not comorbid depressive disorders (aHR 0.99, 95%CI: 0.38-1.26).

Conclusions: In a large national cohort of adults with schizophrenia, suicide risk was elevated with the highest risk among young adult patients. These patterns support suicide prevention efforts with a focus on young people with schizophrenia, especially those with suicidal symptoms and substance use.