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. Author manuscript; available in PMC: 2018 Aug 17.
Published in final edited form as: Forum Health Econ Policy. 2016 May 31;19(2):201–259. doi: 10.1515/fhep-2015-0027

Table B1:

Preliminary Findings of Effects of ACA on Coverage for Young Adults.

Study Data source(s) Study design Findings
Antwi et al. (2013) SIPP - Difference-in-differences model with state fixed effects
- Study period: 2008–2011
- Treatment group: ages 19–25; comparison group: ages 16–18 and 27–29
- 2.6 million young adults added parental ESI after ACA implementation
- Parental ESI rates rose prior to law taking effect
Antwi et al. (2015a) NIS - Difference-in-differences model with year, seasonality, and hospital fixed effects
- Study period: 2007–2011
- Treatment group: ages 19–25; comparison group: ages 27–29
- 12.5% reduction in uninsurance rate among hospitalized young adults ages 19-25
Chua and Sommers (2014) MEPS - Difference-in-differences
- Study period: 2002–2011
- Treatment group: ages 19-25; comparison group: ages 26–34
- 7.2pp increase in probability of insurance coverage among 19- to 25-year-olds as compared to 26- to 34-year-olds
Cohen and Martinez (2015) NHIS - 2014 NHIS coverage estimates - Number of uninsured young adults ages 19–25 fell from 26.5% in 2013 to 20.0% in 2014
Collins et al. (2012) Commonwealth Fund
Health Insurance Tracking
Survey
- Survey results weighted to correct for sample design and nonresponse
- Survey period: November 2010–November 2011
- 13.7 million young adults remained on or joined parent's health insurance plan between November 2010 and November 2011, and 6.6 million would not have been able to do so prior to the ACA
- 39% of young adults ages 19–29 were uninsured at some point in 2011
- 70% of young adults with incomes below 133% FPL were uninsured atsome point in 2011
Collins et al. (2014) Commonwealth Fund
Health Insurance Tracking
Survey
- Survey results weighted to correct for sample design and nonresponse
- Survey periods: July–September 2013, April–June 2014
- 5.7 million fewer uninsured young adults ages 19–34 in April to June 2014 cohort than July to September 2013 cohort
- Uninsurance rate declined from 28% to 18% during this time
Depew (2013) SIPP - Difference-in-differences model with state and year fixed effects
-Study period: 2001–2011
- Treatment group: ages 19–25; comparison group: ages 26–29
- Females ages 19–25 were 3.2pp more likely to have health insurance after the ACA than females ages 26–29
- Similar males 4.7pp more likely to be insured
Lloyd et al. (2014) CPS - Difference-in-differences
- Study period: pre-ACA 2004–2009; post-ACA2010-2011
- Treatment group: ages 19–23 (excluding students) and ages 24–25 (all); comparison group: ages 27–30 (all)
-Percentage of young adults age 26 and under with non-spousal insurance rose 7.2pp between pre-ACA period (2004–2009) and period immediately after implementation (2010–2011)
- Percentage of uninsured young adults decreased 4.5pp
Kotagal et al. (2014) BRFSS
NHIS
- Difference-in-differences
- Study period: pre-ACA 2009; post-ACA 2012
- Treatment group: ages 19–25; comparison group: ages 26–34
- 68.3% to 71.1% increase in coverage for young adults ages 19–25 between 2009 and 2012
Martinez and Cohen (2014) NHIS - NHIS coverage estimates - 4.5 million young adults gained coverage between the implementation of the dependent coverage provision and second quarter of 2014
McMorrow et al. (2015) NHIS - Examined temporal coverage trends
- Study period: 2009–2014
- Uninsurance rate among 19–25 year-olds fell from 30% in 2009 to 19% in second quarter of 2014
- Dependent coverage expansion disproportionately affected higher-income young adults
- Largest reductions in Medicaid expansion states
Mulcahy et al. (2013) IMS Health CDM Database - Difference-in-differences model
- Study period: 2009–2011
- Treatment group: ages 19–25; comparison group: ages 26–31
- 1.7pp decrease in proportion of ED visits by uninsured young adults ages 19–25 between January 2009 and December 2011 compared to adults ages 26–31
- 3.1 pp increase in private coverage rates of nondiscretionary ED visits by young adults
O'Hara and Brault (2013) ACS - Difference-in-differences model with state effects
- Study period: 2008–2011
- Treatment group: ages 19–25; comparison group: ages 26–29
- Private insurance rate increased 4.6pp from 2010–2011 for young adults ages 19–25, corresponding to net increase in coverage of 1.4 million individuals and net decrease in uninsurance of 1.3 million
Scott et al. (2015) National Trauma Data
Bank
- Difference-in-differences model with facility-level fixed effects
- Study period: pre-ACA 2007–2009; post-ACA 2011-2012
- Study population: individuals with trauma experience
- Treatment group: ages 19–25; comparison group: ages 26–34
- Uninsurance rate decreased 3.4pp amongyoung adult trauma patients ages 19–25, as compared to similar adults ages 26-34
- Largest decrease among men and non-Hispanic Whites
Slusky (2012) CPS - Difference-in-differences model with age, state, and time fixed effects
- Study period: pre-ACA 2005–2009; post-ACA 2011
- Treatment group: ages 19–25; comparison group: ages 16–18 and 27–29
- Insurance coverage rate rose 3pp to 4pp for young adults ages 19–25
- Parental insurance coverage rates rose by 7pp–9pp and self-coverage fell by 4pp–5pp
Sommers et al. (2013) NHIS CPS ASEC - Difference-in-differences
- Study period: 2005–2010
- Treatment group: ages 19–25; comparison group: ages 26–34
- 6.7pp increase in proportion of young adults ages 19–25 gaining dependent coverage between September 2011 and September 2012, as compared to adults ages 26–35
Wallace and Sommers (2015) BRFSS - Difference-in-differences model with state and time fixed effects
- Study period: 2005–2012
- Treatment group: ages 19–25; comparison group: ages 26–34
- 6.6pp increased likelihood of having health insurance post-reform foryoung adults ages 19–25, as compared to adults ages 26–34