The Impact of the Affordable Care Act (ACA) Medicaid Expansion on Visit Rates for Diabetes in Safety Net Health Centers

Nathalie Huguet; Rachel Springer; Miguel Marino; Heather Angier; Megan Hoopes; Heather Holderness; Jennifer E. DeVoe

doi:10.3122/jabfm.2018.06.180075

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Table 1.

Characteristics of Community Health Centers and Patients in the Accelerating Data Value Across a National Community Health Center Network Clinical Data Research Network from 2012 to 2015

	Nonexpansion States	Expansion States
	Community health center/state-level covariates
States	FL, KS, MO, NC	CA, HI, MD, NM, OH, OR, RI, WA, WI
No. eligible CHCs	67	131
No. rural CHCs (%)	3 (4.5)	23 (17.6)
No. urban CHCs (%)	64 (95.5)	108 (82.4)
Marketplace type, n (%)
Federally supported, state-based	0	75 (57.3)
Federal	67 (100)	13 (9.9)
State	0	43 (32.8)
Minimum wage, 2013, mean $/h	$7.73	$8.26
Unemployment rate, 2013, mean %	7.26%	7.91%
Adult uninsured rate, 2013, mean %	25.07%	17.62%

Patient-level covariates
Count	Diabetes	Prediabetes	No Diabetes	Diabetes	Prediabetes	No Diabetes
Total no. patients	48,382	69,476	270,608	58,205	87,020	338,687
Established patient visit count pre-ACA, n	217,063	238,129	476,218	379,394	414,318	806,398
Established patient visit count post-ACA, n	168,026	198,079	310,978	332,773	384,859	583,975
New patient visit count pre-ACA, n	8,928	9,389	11,578	29,895	11,998	13,134
New patient visit count post-ACA, n	58,028	73,017	167,133	298,178	76,325	105,671
Female, n (%)	27,485 (56.8)	42,546 (61.2)	173,390 (64.1)	31,250 (53.7)	46,312 (53.2)	191,485 (56.5)
Age group, n (%)
19 to 25 y	1,375 (2.8)	3,745 (5.4)	59,453 (22.0)	1,923 (3.3)	5,867 (6.7)	81,296 (24.0)
26 to 39 y	7,834 (16.2)	16,511 (23.8)	101,157 (37.4)	11,043 (19.0)	24,507 (28.2)	132,408 (39.1)
40 to 64 y	39,173 (81.0)	49,220 (70.8)	109,998 (40.6)	45,239 (77.7)	56,646 (65.1)	124,983 (36.9)
Household income, n (%)
⩽100% FPL	33,779 (69.8)	46,543 (67.0)	181,044 (66.9)	33,721 (57.9)	50,324 (57.8)	182,657 (53.9)
100% to 138% FPL	4,912 (10.2)	6,856 ( 9.9)	27,891 (10.3)	7,199 (12.4)	11,004 (12.6)	37,128 (11.0)
⩽138% FPL	5,834 (12.1)	9,329 (13.4)	32,457 (12.0)	8,099 (13.9)	13,304 (15.3)	52,517 (15.5)
Unknown	3,857 (8.0)	6,748 (9.7)	29,216 (10.8)	9,186 (15.8)	12,388 (14.2)	66,385 (19.6)
Race/ethnicity, n (%)
Hispanic	16,935 (35.0)	27,100 (39.0)	101,690 (37.6)	22,230 (38.2)	28,572 (32.8)	98,218 (29.0)
NH non-white	17,165 (35.5)	21,070 (30.3)	71,111 (26.3)	9,431 (16.2)	12,800 (14.7)	48,178 (14.2)
NH white	12,461 (25.8)	18,481 (26.6)	85,897 (31.7)	24,294 (41.7)	42,040 (48.3)	173,868 (51.3)
Unknown	1,821 (3.8)	2,825 (4.1)	11,910 (4.4)	2,250 (3.9)	3,608 (4.1)	18,423 (5.4)

ACA, Affordable Care Act; CHC, community health center; FPL, federal poverty level; NH, non-Hispanic.

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Table 2.

Visit Rates Before and After Affordable Care Act, Accelerating Data Value Across a National Community Health Center Network Clinical Data Research Network from 2012 to 2015^*

Patient Information	Unadjusted Visit Rate				Covariate Adjusted Visit Rate
	Nonexpansion State		Expansion State		Nonexpansion State		Absolute Rate Difference	Expansion State		Absolute Rate Difference
	Pre-ACA	Post-ACA	Pre-ACA	Post-ACA	Pre-ACA	Post-ACA	Absolute Rate Difference	Pre	Post	Absolute Rate Difference
Uninsured
Diabetes	61.2	52.0	75.3	33.2	43.2	36.7	−6.5	63.1	27.8	−35.3
Prediabetes	52.6	45.1	52.4	25.2	39.8	34.1	−5.7	50.1	24.1	−26.0
No diabetes	30.2	24.6	31.4	14.7	27.6	22.5	−5.1	37.2	17.4	−19.8
Medicaid
Diabetes	37.4	37.1	80.0	125.6	35.8	35.5	−0.3	62.7	98.4	35.7
Prediabetes	29.4	31.4	70.4	120.0	27.9	29.9	2.0	48.9	83.5	34.6
No diabetes	15.0	15.0	31.7	50.6	20.6	20.5	−0.1	36.5	58.3	21.8
Privately insured
Diabetes	9.7	26.9	34.0	37.5	16.0	44.2	28.2	19.2	21.2	2.0
Prediabetes	9.9	31.5	31.3	34.5	18.0	57.0	39.0	20.2	22.3	2.1
No diabetes	4.7	12.6	18.4	19.5	12.0	32.3	20.3	14.5	15.4	0.9
Other public
Diabetes	36.4	28.8	39.9	43.2	47.7	37.7	−10.0	21.6	23.4	1.8
Prediabetes	28.7	24.1	26.9	28.0	48.3	40.5	−7.8	15.8	16.4	0.6
No diabetes	13.2	9.7	7.8	7.0	29.6	21.7	−7.9	6.1	5.5	−0.6
Total Visits
Diabetes	144.8	144.8	229.2	239.5	169.9	169.9	0.0	177.8	185.8	8.0
Prediabetes	120.6	132.1	181.0	207.7	148.8	163.0	14.2	140.2	160.9	20.7
No diabetes	63.1	61.9	89.3	91.9	99.1	97.2	−1.9	90.9	93.6	2.7
Primary care visits
Diabetes	122.6	120.6	190.1	195.8	132.9	130.7	−2.2	140.7	144.9	4.2
Prediabetes	103.6	111.6	152.8	173.6	120.9	130.2	9.3	118.0	134.1	16.1
No diabetes	54.8	52.7	75.4	76.6	90.8	87.4	−3.4	86.2	87.7	1.5
Preventive care visits
Diabetes	4.7	5.9	4.1	4.6	6.6	8.3	1.7	2.9	3.2	0.3
Prediabetes	7.0	9.4	5.2	6.8	10.2	13.8	3.6	4.5	5.9	1.4
No diabetes	5.8	7.0	4.6	5.1	9.9	11.9	2.0	4.3	4.7	0.4
Glucose testing
Diabetes	67.4	81.9	76.6	87.6	65.4	79.5	14.1	78.2	89.5	11.3
Prediabetes	36.3	45.0	35.8	44.2	33.9	42.0	8.1	35.3	43.6	8.3
No diabetes	12.2	14.7	11.1	14.3	18.5	22.3	3.8	19.3	24.8	5.5
HbA1c screening
Diabetes	52.3	76.3	65.5	82.7	53.8	78.4	24.6	70.9	89.5	18.6
Prediabetes	16.0	28.0	10.2	20.3	14.4	25.3	10.9	10.4	20.7	10.3
No diabetes	2.6	4.3	1.3	3.0	3.2	5.5	2.3	2.3	5.2	2.9

ACA, Affordable Care Act.
↵* Nonexpansion states: FL, KS, MO, and NC; expansion states: CA, HI, MD, NM, OH, OR, RI, WA, and WI. Visit rates were by dividing the number of visits in a given interval (ie, pre-ACA or post-ACA period) by the total number of adult patients seen in a clinic over the study period, scaled to 1000 patients per month. Total visits: Current Procedural Terminology (CPT) 99201 to 99205, 99212 to 99215, 99241 to 99245, 99381 to 99384, 99385 to 99387, or 99391 to 99397 with MD, DO, NP, PA, midwife, or resident with no specialty listed. Generalized estimating equation Poisson models adjusted for clinic-level demographic distributions (sex, age, federal poverty level, primary language, race, and ethnicity), state-level factors (marketplace type, 2013 minimum wage and unemployment rates, and 2013 uninsured rate), and 2013 state-level CHCs diabetes prevalence (https://bphc.hrsa.gov/datareporting/index.html) clustered by facility to account for within-facility correlation.

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Table 3.

Adjusted Rate Ratios and Difference-in-Difference in Visit Rates by Diabetes Status and Medicaid Expansion Status, Accelerating Data Value Across a National Community Health Center Network Clinical Data Research Network from 2012 to 2015^*

Patient Information	Nonexpansion	Expansion	Expansion vs Nonexpansion
	Post-ACA vs Pre-ACA	Post-ACA vs Pre-ACA	Expansion vs Nonexpansion
	RR (95% CI)	RR (95% CI)	DD Ratio (95% CI)
Uninsured
Diabetes	0.85 (0.76–0.94)	0.44 (0.39–0.49)	0.52 (0.44–0.60)
Prediabetes	0.86 (0.76–0.95)	0.48 (0.42–0.54)	0.56 (0.47–0.65)
No diabetes	0.82 (0.74–0.89)	0.47 (0.42–0.52)	0.57 (0.50–0.65)
Medicaid
Diabetes	0.99 (0.92–1.07)	1.57 (1.43–1.71)	1.58 (1.40–1.77)
Prediabetes	1.07 (0.98–1.16)	1.71 (1.53–1.88)	1.59 (1.38–1.80)
No diabetes	1.00 (0.91–1.09)	1.60 (1.46–1.73)	1.60 (1.40–1.80)
Privately insured
Diabetes	2.77 (1.79–3.75)	1.10 (0.96–1.25)	0.40 (0.25–0.55)
Prediabetes	3.17 (2.03–4.31)	1.10 (0.90–1.31)	0.35 (0.21–0.49)
No diabetes	2.70 (2.02–3.38)	1.06 (0.94–1.18)	0.39 (0.28–0.50)
Other public
Diabetes	0.79 (0.66–0.92)	1.08 (0.97–1.20)	1.37 (1.10–1.64)
Prediabetes	0.84 (0.65–1.03)	1.04 (0.86–1.22)	1.24 (0.89–1.59)
No diabetes	0.73 (0.59–0.87)	0.90 (0.77–1.04)	1.24 (0.94–1.53)
Total visit
Diabetes	1.00 (0.93–1.07)	1.05 (0.99–1.09)	1.04 (0.95–1.14)
Prediabetes	1.10 (1.00–1.19)	1.15 (1.09–1.20)	1.05 (0.94–1.16)
No diabetes	0.98 (0.91–1.06)	1.03 (0.98–1.08)	1.05 (0.95–1.15)
Primary care
Diabetes	0.98 (0.91–1.06)	1.03 (0.98–1.07)	1.05 (0.96–1.14)
Prediabetes	1.08 (0.98–1.17)	1.14 (1.08–1.19)	1.05 (0.95–1.16)
No diabetes	0.96 (0.88–1.04)	1.02 (0.96–1.07)	1.06 (0.95–1.16)
Preventive Care
Diabetes	1.26 (1.03–1.50)	1.12 (1.02–1.23)	0.89 (0.71–1.08)
Prediabetes	1.35 (1.13–1.58)	1.31 (1.19–1.42)	0.96 (0.79–1.14)
No diabetes	1.20 (1.04–1.37)	1.11 (1.01–1.20)	0.92 (0.77–1.07)
Glucose testing
Diabetes	1.22 (1.11–1.32)	1.14 (1.09–1.20)	0.94 (0.84–1.04)
Prediabetes	1.24 (1.13–1.35)	1.23 (1.17–1.30)	0.99 (0.89–1.09)
No diabetes	1.20 (1.09–1.31)	1.29 (1.21–1.37)	1.07 (0.95–1.19)
HbA1c screening
Diabetes	1.46 (1.35–1.56)	1.26 (1.21–1.31)	0.87 (0.80–0.94)
Prediabetes	1.76 (1.56–1.95)	2.00 (1.80–2.19)	1.14 (0.87–1.40)
No diabetes	1.70 (1.45–1.96)	2.26 (1.97–2.56)	1.33 (1.09–1.57)

ACA, Affordable Care Act; RR, rate ratio; CI, confidential interval; DD, difference-in-difference testing post-period versus pre-period in expansion versus non-expansion states.
↵* Nonexpansion states: FL, KS, MO, and NC; expansion states: CA, HI, MD, NM, OH, OR, RI, WA, and WI. Visit rates were by dividing the number of visits in a given interval (ie, pre-ACA or post-ACA period) by the total number of adult patients seen in a clinic over the study period, scaled to 1000 patients per month. Boldfaced values indicate statistically significant difference, P < .05. Total visits: CPT 99201 to 99205, 99212 to 99215, 99241 to 99245, 99381 to 99384, 99385 to 99387, or 99391 to 99397 with MD, DO, NP, PA, midwife, or resident with no specialty listed. Generalized estimating equation Poisson models adjusted for clinic-level demographic distributions (sex, age, federal poverty level, primary language, race, and ethnicity), state-level factors (marketplace type, 2013 minimum wage and unemployment rates, 2013 uninsured rate), and 2013 state-level CHCs diabetes prevalence (https://bphc.hrsa.gov/datareporting/index.html) clustered by facility to account for within-facility correlation. DD estimates obtained from linear combinations of time × expansion status interaction.

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Appendix:

Community Health Center Visit Rates Before and After Affordable Care Act in Expansion and Nonexpansion States, Accelerating Data Value Across a National Community Health Center Network Clinical Data Research Network from 2012 to 2015

Patient Information	Model Excluding State-Level Factors^*				Model Adjusting for State-Level Factors Excluding DM Prevalence^{^†}				Model Adjusting for State-Level Factors and State DM Prevalence^{^‡}
	Nonexpansion Visit Rate		Expansion Visit Rate		Nonexpansion Visit Rate		Expansion Visit Rate		Nonexpansion Visit Rate		Expansion Visit Rate
	Pre	Post	Pre	Post	Pre	Post	Pre	Post	Pre	Post	Pre	Post
Uninsured
DM	50.1	42.6	62.9	27.8	43.2	36.7	63.1	27.8	46.6	39.6	61.9	27.3
Pre-DM	44.8	38.4	45.4	21.8	39.8	34.1	50.1	24.1	42.8	36.7	48.6	23.3
No DM	36.5	29.8	40.1	18.8	27.6	22.5	37.2	17.4	29.4	23.9	35.7	16.7
Medicaid
DM	32.9	32.7	67.8	106.3	35.8	35.5	62.7	98.4	37.0	36.7	62.8	98.5
Pre-DM	25.2	27.0	53.6	91.4	27.9	29.9	48.9	83.5	28.6	30.7	48.5	82.7
No DM	19.1	19.1	40.0	63.9	20.6	20.5	36.5	58.3	20.8	20.7	35.9	57.3
Privately insured
DM	9.4	26.0	27.8	30.7	16.0	44.2	19.2	21.2	16.6	46.0	19.2	21.2
Pre-DM	10.4	33.1	30.8	34.0	18.0	57.0	20.2	22.3	18.6	58.9	19.9	22.0
No DM	6.0	16.1	19.5	20.6	12.0	32.3	14.5	15.4	12.1	32.8	14.1	15.0
Other public
DM	27.5	21.7	32.1	34.8	47.7	37.7	21.6	23.4	49.2	38.8	21.4	23.2
Pre-DM	26.3	22.1	23.5	24.4	48.3	40.5	15.8	16.4	49.7	41.6	15.6	16.2
No DM	15.0	11.0	8.0	7.2	29.6	21.7	6.1	5.5	30.4	22.2	6.0	5.4
Total visit
DM	139.1	139.1	210.0	219.5	169.9	169.9	177.8	185.8	180.6	180.7	176.7	184.7
Pre-DM	116.8	128.0	160.5	184.1	148.8	163.0	140.2	160.9	157.0	171.9	137.3	157.6
No DM	74.9	73.4	99.4	102.3	99.1	97.2	90.9	93.6	102.6	100.6	87.7	90.3
Primary care
DM	109.1	107.3	162.9	167.7	132.9	130.7	140.7	144.9	140.3	138.0	140.3	144.5
Pre-DM	96.4	103.8	134.5	152.7	120.9	130.2	118.0	134.1	126.6	136.4	116.0	131.7
No DM	70.4	67.8	94.8	96.3	90.8	87.4	86.2	87.7	93.5	90.0	83.5	84.9
Preventive care
DM	4.7	5.9	4.1	4.7	6.6	8.3	2.9	3.2	7.1	8.9	2.9	3.2
Pre-DM	6.6	8.9	6.0	7.8	10.2	13.8	4.5	5.9	10.8	14.7	4.4	5.7
No DM	5.6	6.7	4.8	5.3	9.9	11.9	4.3	4.7	10.4	12.5	4.1	4.5
Glucose testing
DM	71.6	87.0	71.5	81.8	65.4	79.5	78.2	89.5	64.0	77.8	78.6	89.8
Pre-DM	38.3	47.5	33.2	40.9	33.9	42.0	35.3	43.6	33.2	41.2	35.6	43.9
No DM	20.9	25.2	18.2	23.5	18.5	22.3	19.3	24.8	18.2	21.9	19.5	25.1
HbA1c screening
DM	58.8	85.7	68.5	86.4	53.8	78.4	70.9	89.5	57.3	83.5	70.3	88.7
Pre-DM	15.7	27.6	9.9	19.8	14.4	25.3	10.4	20.7	15.2	26.7	10.1	20.2
No DM	3.4	5.9	2.2	5.0	3.2	5.5	2.3	5.2	3.3	5.7	2.2	5.1

ACA, Affordable Care Act; DM, diabetes mellitus; pre, pre-ACA; post, post-ACA.
↵* Adjusted for clinic-level distributions of sex, age, race/ethnicity, and federal poverty level, urban vs. rural clinic location.
↵† Adjusted for clinic-level distributions of sex, age, race/ethnicity, and federal poverty level, urban vs. rural clinic location, and state-level factors (type of health insurance marketplace [state-run or federally facilitated], 2013 minimum wage, 2013 uninsured rate, and 2013 unemployment rate).
↵‡ Adjusted for clinic-level distributions of sex, age, race/ethnicity, and federal poverty level, urban vs. rural clinic location, and state-level factors (type of health insurance marketplace [state-run or federally facilitated], 2013 minimum wage, 2013 uninsured rate, and 2013 unemployment rate), state-level 2013 CHCs DM prevalence (source, HRSA, Health Center Data & Reporting, https://bphc.hrsa.gov/datareporting/index.html).