Associations Between Psychiatric Comorbidities and Cardiovascular Readmissions in Heart Failure: A Nationwide Analysis With a Focus on Substance Use Disorder.

Background Psychiatric comorbidities are known to influence cardiovascular (CV) outcomes, but their specific impact on CV-specific readmissions following heart failure (HF) hospitalization remains unclear. Most prior research has focused on all-cause 30-day readmissions, limiting diagnosis-specific insight and long-term assessment. Methods We conducted a retrospective cohort study using the Nationwide Readmissions Database from 2016 to 2022. Adults (≥18 years) hospitalized with a primary diagnosis of HF were included. The psychiatric comorbidities of depression, anxiety, bipolar disorder, schizophrenia, post-traumatic stress disorder, and substance use disorder (SUD) were identified using ICD-10 codes. CV-specific readmissions at 30 days and one year were identified using ICD-10 codes for hypertension, HF or pulmonary edema, acute myocardial infarction, arrhythmias or conduction disorders, stroke or transient ischemic attack, pulmonary circulation disorders, and venous thromboembolism. Associations were evaluated using adjusted Cox regression models. Results Among 31,886,859 weighted hospitalizations, 6.1% (N = 1,945,098) had 30-day and 12.8% (N = 4,081,518) had one-year CV-specific readmissions. SUD was the only psychiatric condition independently associated with a higher hazard of CV-specific readmission at both time points: HR = 1.03 (95% CI: 1.02-1.03), p < 0.001 at 30 days, and HR = 1.02 (95% CI: 1.02-1.03), p < 0.001 at one year. All other psychiatric conditions were independently associated with a lower hazard of CV-specific readmission. Conclusion SUD may be a distinct risk factor for CV-specific readmissions following HF hospitalization and could benefit from targeted intervention. These findings emphasize the importance of diagnosis-specific transitional care and support the integration of psychiatric screening into CV risk stratification. While causality cannot be inferred due to the observational design, these results underscore the need for prospective studies to clarify underlying mechanisms.