Exhibit 4.

Performance among Medicare ACOs with and without management partners

	Includes Partner	No Partner	p-value on difference
Cost performance
Achieved savings in year 1	23%	17%	n/s
Achieved savings in year 2	23%	25%	n/s
Gross savings per beneficiary in year 1	$72 ($72)	$6 ($52)	n/s
Gross savings per beneficiary in year 2	$117 ($69)	$27 ($71)	n/s
Quality composite score(out of 100 possible points)
Year 1 mean score	63	64	n/s
Year 2 mean score	67	68	n/s
N	56	92

Source: authors’ analysis of the National Survey of ACOs, Waves 1–3

n/s not significant; *p<0.05; **p<0.01; ***p<0.001