Exhibit 1.

Baseline characteristics of patients at index admission, by insurance and condition type, 2010–14

	Medicare (n = 15,135,169)		Medicaid (n = 5,960,797)		Private (n = 9,881,632)		Other (n = 3,856,608)
	Target Conditions (n = 2,500,282)	Control conditions (n = 12,634,887)	Target Conditions (n = 297,543)	Control conditions (n = 5,663,254)	Target Conditions (n = 654,399)	Control conditions (n = 9,227,233)	Target conditions (n = 285,365)	Control conditions (n = 3,571,243)
Patient-level demographic characteristics
Mean age (years)	79.1	78.1	49.7	37.1	57.7	55.0	54.0	43.7
Female (%)	52.9	59.0	47.4	69.7	38.8	63.8	34.3	45.2
Clinical comorbidity with high prevalence in study population (%)a
Anemias	29.84	24.09	23.03	14.79	17.33	11.81	16.64	11.96
Congestive heart failure	11.41	15.46	5.90	2.94	4.65	2.65	4.05	2.72
Chronic pulmonary disease	38.63	21.84	38.77	13.56	26.38	9.95	28.31	10.81
Depression	9.99	11.31	11.24	8.74	8.84	8.57	7.27	8.73
Diabetes	38.45	31.38	38.01	13.62	32.48	13.94	30.64	14.32
Fluid and electrolyte disorders	31.71	32.88	28.67	16.09	24.57	16.65	25.41	21.46
Hypertension	72.74	70.38	59.12	25.04	59.91	31.37	58.44	32.63
Hypothyroidism	18.21	17.86	7.10	4.20	9.48	7.36	6.08	4.45
Peripheral vascular disease	12.77	9.66	5.17	1.47	6.00	2.12	4.72	1.70
Hospitalization characteristics
Mean length-of-stay (days)	5.5	5.4	5.5	4.7	4.6	3.8	4.6	4.3
Mean cost of index hospitalization ($)	12,378.7	10,944.4	14,167.2	8,498.7	15,228.8	8,783.1	13,675.8	8,861.7
Mean cost of readmission ($)	13,607.1	12,832.4	15,282.3	11,253.9	17,126.5	12,350.6	14,919.7	10,682.7

SOURCE Authors’ analysis of data for 2010–14 from the Nationwide Readmissions Database. NOTES The target conditions were acute myocardial infarction, heart failure, and pneumonia. All patients were discharged alive from the hospital. “Other” includes self-pay and uninsured patients.

^aPrevalence greater than 10 percent among patients in at least one insurance type.