Serious mental illness, other mental health disorders, and outpatient health care as predictors of 30-day readmissions following medical hospitalization

Objective: Prior research has not addressed whether both serious mental illness (SMI) and other mental health (OMH) disorders affect the likelihood of 30-day readmissions after medical hospitalizations, or whether post-discharge use of outpatient medical, mental health, and pharmacy services is associated with readmission likelihood. Methods: Using the Truven Health Analytics MarketScan (R) Medicaid Multi-State Database, we studied 43,817 Medicaid beneficiaries, age 18-64, following discharge from medical hospitalizations in 2011. Logistic regression models compared all-cause, 30-day readmissions among those with SMI, OMH, and no psychiatric diagnosis, and examined associations of 30-day outpatient service use with 30-day readmissions. Results: Thirty-day readmission rates were 15.9% (SMI), 13.8% (OMH), and 11.7% (no mental illness). In multivariable analysis, compared to patients without mental illness, odds of readmission were greater for those with SMI (aOR = 1.43, 95%CI:1.32-1.51) and OMH (aOR = 1.21, 95%CI:1.12-1.30), and lower among those using outpatient mental health services (aOR = 0.50, 95%CI: 0.44-0.56). Conclusion: The adult Medicaid population disproportionately includes patients with SMI and OMH disorders, both of which were found to be associated with 30-day hospital readmissions. Receiving outpatient mental health services after hospital discharge may be protective against readmission following medical hospitalizations, suggesting the need for further research on these topics.