State-level variability in discharge to inpatient rehabilitation after severe traumatic injuries

INTRODUCTION Rehabilitation at inpatient rehabilitation facilities (IRFs) has been shown to improve seriously injured patients' long-term functional independence. However, not all patients with severe injuries are discharged to an IRF. The aim of this study is to examine differences in the proportion of severely injured patients discharged to IRFs across US states and assess the association between the regional supply of IRFs and the likelihood of IRF discharge. METHODS We performed a retrospective analysis of 2021 Healthcare Cost and Utilization Project State Inpatient Databases across 13 states. We included severely injured (ISS >15) adult patients who survived to hospital discharge. We calculated the marginal probability of discharge to IRF, skilled nursing facility, home health agency, or home without services across states using a multinomial logistic regression model to control for patient demographics, insurance type, injury severity, medical comorbidities, and trauma center level. We also performed a mixed-effects logistic regression to evaluate the association between the supply of IRFs within individual states with the likelihood of discharge to IRF. RESULTS We identified 104,017 severely injured patients. Across all 13 included states, 13% of patients were discharged to IRFs. There was considerable variation in the adjusted probability of discharge to an IRF across states, ranging from 6.4% in Oregon (95% confidence interval CI, 5.6–7.1%) to 22.1% in Kentucky (95% CI, 20.8–23.4%), after controlling for potential confounders. The state-level supply of IRFs ranged from 0.49 to 8.63 per 1,000,000 population in Maryland and Arkansas, respectively. Each additional IRF per 1,000,000 population was associated with 11% increased odds of discharge to IRF (95% CI, 1.01–1.21; p = 0.024). CONCLUSION Severely injured patients face substantial differences in accessing high-level rehabilitation care at an IRF depending on their state of residence. Increasing the availability of IRFs within underserved states may improve access to specialized rehabilitation care for trauma patients. LEVEL OF EVIDENCE Therapeutic/Care Management; Level III.