Table 1.

Sample Characteristics of Medicare Beneficiaries Based on Admission to ACO and Non-ACO Hospitals from 2010 to 2013

	Admission to pre-ACO	Admission to post-ACO	Non-ACO pre 01/01/2013	Non-ACO post 01/01/2013
Unique benificiaries	927,180	363,468	8,155,756	2,237,169
Total number of admissions	2,146,586	786,678	18,779,688	4,789,864
Age, mean (SD)	79.18 (7.72)	79.20 (7.77)	79.00 (7.69)	79.06 (7.75)
Male (%)	41.87	42.08	41.91	42.21
Race (%)
Black	8.44	8.36	9.74	9.67
White	87.90	87.88	85.37	85.21
Hispanic	1.40	1.30	1.95	1.90
Other	2.26	2.46	2.94	3.22
Elixhauser comorbidity score (SD)	8.77 (7.90)	9.56 (8.45)	8.64 (7.81)	9.49 (8.34)
Dual eligible (%)	21.16	19.04	23.54	22.53
Primary diagnosis % (top 5)
Major joint replacement of lower extremity	4.75	5.44	4.86	5.42
Heart failure and shock	5.00	4.96	5.19	5.17
Simple pneumonia and pleurisy	3.67	3.78	4.07	4.26
Septicemia or severe sepsis	3.48	4.39	3.75	4.83
COPD	3.49	3.23	3.80	3.71
Comorbidity % (top 5)
Hypertension	49.38	51.69	49.87	51.58
Hyperlipidemia	38.51	46.01	37.37	44.12
Coronary atherosclerosis	35.60	38.46	34.99	37.30
Cardiac arrthymia	31.40	34.66	30.29	33.39
Fluid or electrolyte disorder	28.38	31.43	29.21	32.3
Urban zipcode (%)	94.45	94.12	91.62	91.68
Discharge location (%)
SNF	26.41	26.72	23.65	24.42
IRF	3.93	4.14	3.64	3.81
Home with services (HHA)	12.68	13.34	11.84	12.78
Home	55.67	54.33	59.37	57.36
Other	1.31	1.47	1.50	1.63
30-day readmission rate	16.76	15.60	16.44	15.75
30-day mortality rate	4.69	4.73	4.92	5.03

ACO accountable care organization, SD standard deviation, SNF skilled nursing facility, IRF inpatient rehabilitation facility, HHA Home Health Agency, PAC post-acute care