Table 1.

Patient, health system, and community characteristics by ACO participation, level of informal clinical integration

	Lower integration		Moderate integration		Higher integration		Overall p-value	Non-ACO		ACO Pre-Joining		ACO Post-Joining		Overall p-value
Variable	Mean	SD	Mean	SD	Mean	SD		Mean	SD	Mean	SD	Mean	SD
Beneficiary characteristics
Patient mortality (90-day)	0.08	0.27	0.07	0.25	0.05	0.22	<0.01	0.07	0.25	0.07	0.25	0.07	0.25	0.94
Charlson score	2.05	1.97	1.96	1.92	1.71	1.75	<0.01	1.91	1.89	1.99	1.93	2.16	2.04	<0.01
Emergent surgery	0.19	0.39	0.21	0.41	0.23	0.42	<0.01	0.22	0.41	0.19	0.4	0.19	0.39	<0.01
Died 3 days post-CABG (0 = No, 1 = Yes)	0.01	0.12	0.01	0.11	0.01	0.12	0.63	0.01	0.12	0.01	0.12	0.01	0.11	0.99
Sex (0 = Male, 1 = Female)	0.30	0.46	0.30	0.46	0.29	0.45	0.07	0.3	0.46	0.3	0.46	0.28	0.45	0.31
White (0 = No, 1 = Yes)	0.93	0.25	0.94	0.24	0.95	0.22	<0.01	0.94	0.24	0.94	0.24	0.94	0.24	1.00
Black (0 = No, 1 = Yes)	0.04	0.20	0.04	0.19	0.03	0.16	<0.01	0.04	0.19	0.04	0.19	0.04	0.19	0.94
Age	75.00	5.92	74.84	5.83	74.62	5.69	<0.01	74.78	5.81	75.03	5.88	75.01	5.96	<0.01
Lives in a rural area	0.01	0.08	0.01	0.08	0.01	0.08	1.00	0.01	0.09	0.01	0.08	0.00	0.05	0.86
% living below federal poverty line (mean)	14.19	3.92	14.87	3.76	15.70	4.23	<0.01	15.18	3.91	13.88	3.92	13.88	4.17	<0.01
% with a bachelor’s degree (mean)	27.55	7.33	26.02	6.99	24.36	6.86	<0.01	25.16	6.85	27.99	7.23	31.59	7.31	<0.01
Health system characteristics
Total CABG beneficiaries (mean)	25.20	18.83	19.35	13.75	13.89	9.17	<0.01	19.22	14.7	24.19	18.55	21.68	16.23	<0.01
Total physicians caring for CABG (mean)	175.16	145.17	111.63	73.21	64.10	37.72	<0.01	113.34	93.84	162.36	151.83	152.04	111.71	<0.01
Proportion of cross-specialty ties	0.53	0.06	0.56	0.06	0.61	0.06	<0.01	0.57	0.07	0.55	0.06	0.54	0.06	<0.01
Proportion of beneficiaries from outside the CBSA	0.59	0.24	0.61	0.24	0.58	0.26	<0.01	0.59	0.24	0.6	0.25	0.62	0.25	<0.01
Academic hospital (0 = No, 1 = Yes)	0.73	0.44	0.64	0.48	0.56	0.50	<0.01	0.6	0.49	0.78	0.42	0.77	0.42	<0.01
Government hospital (0 = No, 1 = Yes)	0.08	0.27	0.08	0.26	0.08	0.27	0.11	0.1	0.31	0.03	0.18	0.01	0.11	<0.01
For-profit hospital (0 = No, 1 = Yes)	0.09	0.29	0.11	0.32	0.13	0.34	<0.01	0.15	0.35	0.03	0.18	0.03	0.16	<0.01
Electronic health records (0 = No, 1 = Yes)	0.97	0.16	0.97	0.17	0.97	0.18	0.06	0.96	0.19	0.98	0.13	1.00	0.05	<0.01
Health system integration	0.01	0.02	0.04	0.01	0.09	0.03	<0.01	0.04	0.04	0.03	0.03	0.03	0.03	<0.01
Pioneer ACO (0 = No, 1 = Yes)	0.02	0.13	0.01	0.09	0.01	0.07	<0.01	0.00	0.00	0.03	0.16	0.06	0.25	<0.01
Joined ACO (0 = No, 1 = Yes)	0.08	0.26	0.06	0.23	0.05	0.21	<0.01	0.00	0.00	0.00	0.00	1.00	0.00	<0.01
Community characteristics
Total resident population (log)	6.13	1.02	5.90	0.95	5.55	0.84	<0.01	5.9	1.01	5.97	0.89	5.96	1	<0.01
Total black population (log)	3.90	1.78	3.48	1.77	2.71	1.73	<0.01	3.48	1.88	3.57	1.71	3.4	1.72	<0.01
Total Hispanic population (log)	3.72	1.59	3.30	1.54	2.86	1.45	<0.01	3.33	1.62	3.49	1.44	3.53	1.65	<0.01
Acute care hospital beds per 1,000 residents	1.99	0.48	1.97	0.48	2.00	0.52	0.01	2.02	0.51	1.92	0.44	1.86	0.38	<0.01
PCPs per 100,000 residents	72.58	18.16	69.09	15.38	65.93	14.10	<0.01	68.01	16.26	73.39	16.34	75.39	17.67	<0.01
Medical specialists per 100,000 residents	55.99	18.10	50.38	14.26	44.87	11.32	<0.01	49.71	15.26	54.98	16.61	57.52	18.99	<0.01
Surgeons per 100,000 residents	37.01	7.97	36.19	7.78	34.87	7.62	<0.01	36.09	7.97	36.54	7.71	36.71	7.38	<0.01

ACO: accountable care organization; CBSA: core-based statistical area; PCP: primary care physician

p-values from Kruskal-Wallis test except for categorical variables (χ² test)