TABLE 1.

Summary of Descriptive Variables of Respondent Organizations and Statistically Significant Differences Between the Target Population and Survey Respondents

ACO Characteristic	Groupings	ACO Database n = 847 (%)	NPC Survey n = 49 (%)	Significant Differencesa
Provider type	Hospital systemb	27.4	28.6
	Physician groupc	42.7	24.5	≤ 0.05
	Integrated systemd	30.0	47.0	≤ 0.05
Percentage in rural arease	None	6.1	2.0
	< 50%	59.5	63.3
	≥ 50%	34.4	34.7
Estimated ACO member volumef	Fewer than 5,000	41.4	2.0	≤ 0.01
	5,001 to 20,000	43.6	20.4	≤ 0.01
	20,001 to 100,000	5.7	51.0	≤ 0.01
	100,001 or more	9.3	26.5	≤ 0.01
CMS programsg	Yes	56.6	55.0

^aSignificant P values are listed.

^bHospital systems are ACOs that are hospitals or hospital systems.

^cPhysician groups are ACOs comprising physicians or physician groups.

^dIntegrated systems are ACOs comprising both hospitals and physician groups.

^eRural areas were defined as the number of nonurban areas as defined by the U.S. Census Bureau ZIP codes covered in the hospital referral region.³⁶

^fACO member volume was defined as the number of patients for whom the ACO is responsible.

^gACOs were considered CMS ACOs if they participated in the Pioneer, Medicare Shared Savings Program, Next Generation ACO Model, or the Oncology Care Model.

ACO = accountable care organization; CMS = Centers for Medicare & Medicaid Services; NPC = National Pharmaceutical Council.