OBJECTIVES: Evaluate the prevalence and likelihood of hospital admission and readmission based on age and insurance type in two cohorts of patients with severe mental illness (SMI).

METHODS: Retrospective analysis using a large sample of private commercial, managed Medicare, and managed Medicaid claims from 2011 to 2016. Cohort definitions: early episode (EE) included patients with six-months of pre-index enrollment with no antipsychotic treatment or SMI diagnosis; recently discharged (RD) included patients with ≥1 SMI related hospitalization. Logit regression was used to model likelihood of hospital admission and readmission. The index event was the first claim with SMI diagnosis or antipsychotic fill. Inclusion criteria: 1)enrolled with medical and pharmacy benefits for ≥180 days before and ≥365 days after index; 2)≥1 inpatient or ≥2 outpatient claims with SMI diagnosis and ≥1 antipsychotic fill; 3)were ≥18 and <65 years old on index. Study population: EE=40,655; RD=11,050; female(63%; 62%); age 18-25(12%; 9%), 26-45(39%; 35%), 46-64(49%; 56%); Medicaid(68%; 65%), Medicare(22%; 20%), commercial(20%; 15%).

RESULTS: EE cohort mean rate of admissions=120 per 1,000, 70 psychiatric related; RD rate of all-cause readmissions=130 per 1,000, 80 psychiatric related. Females were less likely to be admitted(OR=0.94,P=0.02) or readmitted(OR=0.87,P=0.00). EE patients age 18-25(OR=0.86,P=0.00) and 26-45(OR=0.95,P=0.08) were less likely to be admitted, while RD patients age 26-45(OR=1.10,P=0.04) were most likely to be readmitted. Newly diagnosed patients with Medicaid(OR=1.25,P<0.001) or commercial(OR=1.12,P=0.01) insurance were more likely to have an initial hospitalization, but less likely to be readmitted(OR=0.92,P=0.11; OR=0.66,P=0.03).

CONCLUSIONS: Females and newly diagnosed patients age ≤45 are less likely to be hospitalized compared to males and patients age 46+, but SMI patients age 26-45 with a recent hospitalization have the highest likelihood of readmission. Patients with Medicaid or commercial insurance are more likely to be hospitalized following diagnosis, but less likely to be readmitted, suggesting better follow-up care following an inpatient stay.