Table 1.

Characteristics associated with remaining in the ACO for 24 months vs. leaving earlier

	<24 months in the ACO	24+ months in the ACO	OR	95% CI	95% CI
Number of Subjects	145,905	192,823
Female (%)	53.0%	54.3%	1.02	1.01	1.04
Aged <18 years	15.3%	17.8%	0.70	0.68	0.72
Aged 18–25 years	12.2%	11.2%	0.67	0.65	0.69
Aged 26–35 years	25.0%	14.1%	0.49	0.48	0.50
Aged 36–45 years	15.7%	16.0%	0.88	0.86	0.91
Aged 46–55 years	14.8%	19.6%	1.14	1.11	1.17
Aged 56–64 years	16.9%	21.4%	reference
Mean HHS-HCC risk score in ACO entry year	1.22	1.24	0.990	0.988	0.992
Percentage of medical spending on care performed within the ACO in the first quarter	55.8%	66.4%	1.003	1.003	1.004
Plan type – HMO	47.9%	39.7%	reference
Plan type – PPO	49.4%	57.3%	1.14	1.12	1.16
Plan type - POS	2.7%	2.9%	1.17	1.12	1.22

Notes: ACO: accountable care organization; OR: odds ratio; CI: confidence interval; HHS-HCC: refers to a measure of predicted medical spending, i.e., the Department of Health and Human Services-Hierarchical Condition Categories; HMO: health maintenance organization; PPO: preferred provider organization; POS: point of service. Logistic regression models adjusting for insurance plan, year of entry, primary physician practice group.