Importance: Although adults with schizophrenia have an increased risk of suicide, sample size limitations of previous research have hindered characterizations of suicide risk across the life span.
Objective: To describe suicide mortality rates and correlates among adults with schizophrenia across the life span and standardized mortality ratios (SMRs) for suicide compared with the general US population.
Design, setting, and participants: Five national retrospective longitudinal cohorts of patients with schizophrenia in the Medicare program from January 1, 2007, to December 31, 2016, were identified by age: 18 to 34, 35 to 44, 45 to 54, 55 to 64, and 65 years or older. Death record information was obtained from the National Death Index. The total cohort included 668 836 Medicare patients with schizophrenia, 2 997 308 years of follow-up, and 2218 suicide deaths. Data were analyzed from September 30, 2020, to March 10, 2021.
Main outcomes and measures: For each age group, suicide mortality rates per 100 000 person-years and adjusted hazard ratios (aHRs) with 95% CIs of suicide were determined. Suicide SMRs were estimated for the total cohort and by sex and age cohorts standardized to the general US population by age, sex, and race/ethnicity.
Results: The study population of adults 18 years and older included 668 836 Medicare recipients with schizophrenia (52.5% men, 47.5% women). The total suicide rate per 100 000 person-years was 74.00, which is 4.5 times higher than that for the general US population (SMR, 4.54; 95% CI, 4.35-4.73) and included a rate of 88.96 for men and 56.33 for women, which are 3.4 (SMR, 3.39; 95% CI, 3.22-3.57) and 8.2 (SMR, 8.16; 95% CI, 7.60-8.75) times higher, respectively, than the rates for the general US population. Suicide rates were significantly higher for men (aHR, 1.44; 95% CI, 1.29-1.61) and those with depressive (aHR, 1.32; 95% CI, 1.17-1.50), anxiety (aHR, 1.15; 95% CI, 1.02-1.30), drug use (aHR, 1.55; 95% CI, 1.36-1.76), and sleep disorders (aHR, 1.22; 95% CI, 1.07-1.39), suicidal ideation (aHR, 1.41; 95% CI, 1.22-1.63), and suicide attempts or self-injury (aHR, 2.48; 95% CI, 2.06-2.98). The adjusted hazards of suicide were lower for Hispanic patients (aHR, 0.66; 95% CI, 0.54-0.80) or Black patients (aHR, 0.29; 95% CI, 0.24-0.35) than White patients. The suicide rate declined with age, from 141.95 (SMR, 10.19; 95% CI, 9.29-11.18) for patients aged 18 to 34 years to 24.01 (SMR, 1.53; 95% CI, 1.32-1.77) for patients 65 years or older. The corresponding declines per 100 000 person-years were from 153.80 (18-34 years of age) to 34.17 (65 years or older) for men and from 115.70 (18-34 years of age) to 18.66 (65 years or older) for women. In the group aged 18 to 34 years, the adjusted hazards of suicide risk were significantly increased for patients with suicide attempt or self-injury (aHR, 2.57; 95% CI, 18.20-2.04) and with comorbid drug use disorders (aHR, 1.48; 95% CI, 1.17-1.88), but not with comorbid depressive disorders (aHR, 0.99; 95% CI, 0.38-1.26) during the year before the start of follow-up.
Conclusions and relevance: In this cohort study of adult Medicare patients with schizophrenia, suicide risk was elevated, with the highest absolute and relative risk among young adults. These patterns support suicide prevention efforts with a focus on young adults with schizophrenia, especially those with suicidal symptoms and substance use.