Emergency department use by adult medicaid patients after implementation of managed care

Objective: To determine whether the advent of a mandatory Medicaid managed care (MMC) plan had any effect on emergency department (ED) utilization by adult Medicaid patients at an urban teaching hospital. Methods: This was a retrospective cohort study using four years of ED records encompassing the year prior to initiation of MMC (1994-95), the enrollment year (1995-96), a nd two years after the program had matured (1996-98). Results: Total ED cen sus declined slightly, then returned to 1995 levels. Emergency department u se by MMC patients declined steadily, with the 1998 figure of 5,888 represe nting a 40% decline over the pre-MMC volume of 9,849. Visits by MMC patient s with acute illness or injury declined by 29%; MMC low-acuity visits decre ased by 43%. Medicaid managed care low-acuity after-hours/weekend visits de clined by 19%, then leveled off. The MMC enrollment was stable throughout t he study period. Conclusions: Mandatory managed care can be associated with considerable diminution in ED use by Medicaid patients. This decline is mo st pronounced in low-acuity triage categories, and least evident after hour s and on weekends.