Table 2.

Associations Between 2014 Accountable Care Organization (ACO) Savings Rate and Beneficiary, ACO, and Service Area Characteristics

Service Area Social Deprivation index
    Quartile 1 (least deprived)Reference categoryReference category
    Quartile 2−1.32[−2.74, 0.10]−1.06[−2.42, 0.31]
    Quartile 3−1.40[−2.97, 0.18]−2.68[−4.23, −1.14]
    Quartile 4 (most deprived)0.05[−1.44, 1.55]−2.29[−3.97, −0.61]
Organization characteristics
    Number of assigned beneficiaries
        <10,000Reference category
        10,000∼29,999−0.55[−1.78, 0.69]
        ≥30,000−0.68[−2.23, 0.87]
    Entry Year
        2012Reference category
        2013−1.12[−2.41, 0.18]
        2014−1.85[−3.01, −0.69]
        NortheastReference category
        Midwest1.26[−0.22, 2.74]
        South2.44[0.76, 4.12]
        West−1.78[−3.62, 0.07]
    Track 24.43[2.29, 6.58]
    Historical benchmark in quartiles
        Quartile 1Reference category
        Quartile 21.27[−0.06, 2.6]
        Quartile 33.31[1.81, 4.81]
        Quartile 45.07[2.96, 7.17]
    % PCP0.00[−0.03, 0.03]
Beneficiary characteristics
    % Aged 85 and older−0.26[−0.51, 0.00]
    % Female0.11[−0.18, 0.41]
    % White0.03[−0.03, 0.08]
    % Aged dual eligibles0.05[−0.02, 0.13]
    % Disabled0.08[−0.01, 0.17]
    HCC score−2.95[−13.09, 7.19]
  • CI, confidence interval; HCC, Hierarchical Condition Category; PCP, primary care physician.

  • Sources: Accountable Care Organizations (ACOs) were identified using the 2014 Shared Savings Program (SSP) ACO Provider File. Their beneficiaries were identified using the 2014 SSP Beneficiary File. The beneficiary ZIP codes were from the 2014 Master Beneficiary Summary File. ACO savings rate and characteristics were from the 2014 SSP ACO Public Use File. Service area characteristics were from the American Community Survey.

  • To generate the ACO service area, we summed the number of beneficiaries per ZIP code tabulation area (ZCTA), rank ordered those ZCTAs from most to least, and identified those ZCTAs comprising 70%.

  • The social deprivation index (SDI) is a measure of social and material deprivation, constructed by combining a variety of established publicly available socioeconomic measures into a composite measure using a latent variable approach. We conducted regression where the savings rate was the dependent variable.