Study objective: Federal policy changes and tightened state budgets may reduce Medicaid enrollment in many states. In March 2003, the Oregon Health Plan (Oregon's Medicaid expansion program) made substantial changes in its benefit package that resulted in the disenrollment of more than 50,000 beneficiaries. We sought to study the impact of these Oregon Health Plan policy changes on statewide emergency department (ED) use.
Methods: In this observational study, hospital billing data on 2,680,954 visits to 26 Oregon EDs were obtained, sampled up to 24 months before and 24 months after the cutbacks. These visits represent approximately 62% of all visits to Oregon's 58 EDs. We ascertained counts of ED visits by payer group before and after the Oregon Health Plan cutback date, plus hospital admissions from the ED as a measure of acuity.
Results: After the Oregon Health Plan policy changes, ED visits by the uninsured underwent an abrupt and sustained increase, from 6,682 per month in 2002 to 9,058 per month in 2004. Oregon Health Plan-sponsored and commercially insured visits decreased, resulting in a slight decrease in overall ED visits. Multivariable models adjusting for secular trends and seasonality showed a 20% (95% confidence interval 13% to 28%) increase in uninsured ED visits, whereas the adjusted number of Oregon Health Plan-sponsored visits decreased. The proportion of uninsured ED visits resulting in hospital admission increased (odds ratio 1.50; 95% confidence interval 1.39 to 1.62).
Conclusion: Oregon's Medicaid cutbacks were followed by increases in ED use and hospitalizations by the uninsured. Recent federal legislation facilitating similar Medicaid changes in other states may lead to replication of these events elsewhere.