Psychiatric inpatient bed capacity and suicide mortality in Sweden: a nationwide ecological study.

Background: Suicide is a leading cause of premature mortality worldwide, but the impact of system-level mental health resources remains unclear despite the central role of psychiatric inpatient care and declining bed capacity. Prior research has yielded inconsistent findings with limited control for confounding. We aimed to estimate the effect of psychiatric inpatient bed availability on suicide mortality in a universal, publicly dominated mental health-care system. Methods: We conducted a nationwide ecological study using data from 20 Swedish counties between 2015 and 2024. Suicide mortality was obtained from the Cause of Death Register. Psychiatric inpatient bed availability and county-level healthcare budget allocation were extracted from Swedish Municipalities and Regions. Pooled cross-sectional quasi-Poisson regression models, fixed effects models, and Bayesian hybrid mixed-models were used to estimate effects between and within counties. The primary effect estimate was the percentage change in suicide mortality associated with a 10-bed increase per 100,000 inhabitants. Findings: Psychiatric bed capacity declined nationwide from approximately 30.6 beds per 100,000 inhabitants in 2015 to 24.2 in 2024. The overall between-county effect was estimated to 0.892 (95% CI: 0.827-0.961). In the primary analysis of within-county effects, each 10-bed increase per 100,000 inhabitants was associated with a 7.6% reduction in suicide mortality (rate ratio 0.924, 95% CI: 0.881-0.969; p = 0.001). In the Bayesian within-between decomposition models, only the within-county effect of psychiatric bed capacity was fully within the credible intervals (95% credible interval 0.852-0.994). Interpretation: Greater psychiatric bed availability was associated with lower suicide rates, highlighting the inverse association of inpatient care availability and suicide mortality in a high-income country. Extrapolating to Sweden's population of 10.6 million in 2024, a return to the psychiatric bed capacity of 2015 would correspond to approximately 83 fewer suicides annually, assuming that the association is causal. Safeguarding timely access to inpatient psychiatric care may be an important component of national suicide-prevention strategies. Funding: USVE grants.