Exhibit 4.

Change in readmission rates after implementation of the Hospital Readmissions Reduction Program (HRRP) for target conditions, compared to control conditions

	Change (% per quarter)
	Target condition(s)	Control conditions	Difference
ALL THREE TARGET CONDITIONS COMBINED
Medicare	−0.018	0.032	−0.049****
Medicaid	−0.112	−0.068	−0.044****
Private	0.013	−0.017	0.030****
Other	0.022	−0.014	0.036****
ACUTE MYOCARDIAL INFARCTION
Medicare	0.007	0.032	−0.025****
Medicaid	−0.166	−0.068	−0.098****
Private	0.010	−0.017	0.027****
Other	0.027	−0.014	0.041****
HEART FAILURE
Medicare	−0.046	0.032	−0.077****
Medicaid	−0.098	−0.068	−0.030**
Private	−0.057	−0.017	−0.040****
Other	0.150	−0.014	0.164****
PNEUMONIA
Medicare	−0.032	0.032	−0.064****
Medicaid	−0.147	−0.068	−0.079****
Private	0.076	−0.017	0.093****
Other	−0.041	−0.014	−0.027**

SOURCE Authors’ analysis of data for 2010–14 from the Nationwide Readmissions Database NOTES “Control conditions” are those other than the three target conditions, as explained in the text. “Other” includes self-pay and uninsured patients.

^**p < 0:05

^****p < 0:001