DISCRETE EVENT SIMULATION OF PATIENT ADMISSIONS TO A NEUROVASCULAR UNIT

Purpose: There is strong evidence that clinical outcomes are improved for stroke patients admitted to specialized stroke units, but little is known about the operational impact of creating a stroke unit.   Without additional resources, beds are typically taken from internal medicine, neurology, and neurosurgery services to make up the new Neurovascular Unit (NVU) to care for patients with stroke or acute neurovascular injury. Under resource-constrained conditions, the effects on the hospital-system are unknown.

Method: A discrete event simulation was developed to represent patient admissions, movement, length of stay (LOS), and cost given a variety of hypothetical NVU bed arrangements, and patient volumes.  Patient-level data for NVU-eligible patients at the Toronto Western Hospital (TWH) were used to model arrival rates, and LOS. Descriptive analysis and non-parametric testing was conducted to determine differences prior to and post NVU implementation.

Result: In the first year of operation, the NVU handled 77% of eligible patient volumes. Only 4% remained as GIM patients, dropping from 24% pre-NVU. With the introduction of the NVU, average cost per visit and per bed-day decreased by 5% and 12% respectively post-NVU for neurology patients with stroke and acute neurovascular injury. Acute LOS decreased by up to 16%. Scenario testing demonstrated that typical patient volumes seen at TWH would be appropriately satisfied with 20 beds with additional capacity for patient volume increases up to 20%.

Conclusion: The effects on hospital operations of re-organizing limited bed resources into an NVU is minimal.  An NVU was successfully implemented at a major acute care hospital with decreased acute LOS, and lower total cost per year for the care of NVU-eligible patients.