Table 1.

Baseline characteristics of individuals by Affordable Care Act Medicaid expansion status*

Characteristics	Expansion states (n=11 708)	Non-expansion states (n=8448)	P value
Mean (SD) age (years	38.4 (15.7)	38.0 (16.0)	0.40
Female (%)	55.6	56.8	0.31
Race/ethnicity (%):			0.02
White, non-Hispanic	44.2	45.9
Hispanic	29.2	25.4
Black, non-Hispanic	17.0	24.0
Other	9.5	4.7
Education (%):			0.03
<High school	29.1	27.8
High school or some college	60.7	64.4
Bachelor's degree	8.0	6.6
>Bachelor's degree	2.1	1.3
Employed (%)	43.6	46.8	0.04
Married (%)	31.1	33.6	0.22
Mean (SD) family size	2.8 (2.2)	2.8 (2.2)	0.82
Number of children aged ≤18 (%):			0.64
0	51.5	51.8
1	16.6	17.5
2 or more	31.9	30.7
Mean family income ($)	15256	15076	0.55
Health insurance (%)†:
Private insurance (%)	22.6	27.1	0.01
Medicaid (%)	42.7	25.1	<0.001
Uninsured (%)	31.7	44.1	<0.001
Study outcomes ($):
Out-of-pocket spending‡	429	538	0.01
Premium contributions§	688	827	0.09
Out-of-pocket plus premium spending§	1418	1770	0.009
Catastrophic financial burden¶	18.8	21.5	0.04

SD=standard deviation. $1=£0.77; €0.90.

^*Values are weighted to be nationally representative of individuals aged 19-64 years with family incomes lower than 138% of the federal poverty level based on the pooled data of Medical Expenditure Panel Survey 2010-13. US dollars are adjusted for inflation to 2017 using the consumer price index.

^†Definitions of health insurance variables shown in appendix section 2.

^‡Out-of-pocket spending includes deductibles, copayments, and coinsurance paid by each individual.

^§Family level premium contributions were assigned to each individual in the family. Similarly, family level out-of-pocket plus premium spending were calculated by summing out-of-pocket spending paid by all family members and family level premium contributions, and then assigning the value to each member of the family.

^¶Defined as annual out-of-pocket plus premium spending exceeding 40% of post-subsistence income.