When Coverage Expands

Children's Health Insurance Program as a Natural Experiment in Use of Health Care Services

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The Issue:
Expanding health insurance coverage aims to reduce financial barriers to primary care and improve care efficiency by minimizing emergency department (ED) use. This study examines emergency and outpatient department use after the Children’s Health Insurance Program (CHIP) coverage expansion. The study compared adolescents, a major target group for CHIP, to young adults.

Key Findings

  • The mean number of population-adjusted outpatient visits increased by 299 visits per 1,000 among adolescents from the pre-CHIP to CHIP period.

  • The mean population-adjusted annual number of ED visits for young adults increased by 48 visits per 1,000 from the pre-CHIP to CHIP period.

  • The ratio for outpatient-to-ED visits for adolescents increased significantly by 1.04 over the time period, while the ratio for young adults decreased significantly by -0.53.

Conclusion:
This study shows that since the implementation of CHIP, overall visits to outpatient settings among adolescents have significantly increased and ED visit rates remained relatively unchanged.

About the Study:
This was a retrospective cohort study using data from the National Ambulatory Medical Care Survey (NAMCS) and the National Hospital Ambulatory Medical Care Survey (NHAMCS). Data for the years 1992 to 1996 provided a baseline, and was compared to use patterns after the CHIP launch, from 1999-2009.