Table 1.

Practice Attributes by Ownership Structure

Ownership Structurea
IndependentMedical GroupbSimpleb SystemComplexb SystemP Valuec
Sample attributes
Practices, n366.0246.0223.0575.0NA
Percent of sample  26.0  17.4  15.8  40.8NA
Unique systems, n        NA158.0130.0145.0NA
Total no. of physicians, mean (SD)        NA123.6 (241.8)462.7 (498.8)3,734.9 (4,947.3)<.001
Total no. of hospitals, mean (SD)        NA  NA4.0 (6.4)33.2 (39.4)<.001
Practice attributes
Practice size based on number of clinicians in practice, mean (SD)
    Physicians plus other cliniciansd  9.1 (8.3)15.3 (19.9)13.0 (20.8)19.9 (142.2)<.001
    Physicians onlyc  6.0 (6.4)11.1 (15.6)  9.7 (17.3)17.0 (134.2)<.001
Practices with pediatric-trained primary care physicians, %
    All pediatric-trained primary care92.595.393.693.3  .754
    Family medicine practitioners89.693.592.491.1  .592
    OB-GYN physicians10.225.615.415.5  .007
    Med-Peds physicians  2.3  5.9  7.6  8.9  .002
Practices with physicians with potential to provide pediatric behavioral health advice, % with ≥1
    General psychiatristc  1.9  6.0  8.3  5.0  .007
    Child psychiatristc  1.4  1.7  0.9  1.2  .899
    General pediatricianc16.029.323.021.4  .043
    Specialist pediatricianc,e  6.611.5  6.1  8.8  .401
Percentage of annual practice revenue by source, mean (SD)
    Commercial39.4 (22.2)42.1 (23.8)36.2 (20.6)44.4 (18.2)  .001
    Medicaidc20.2 (20.3)19.9 (21.9)24.0 (20.8)17.8 (15.4)  .072
    Self-pay and other13.3 (14.2)10.4 (9.3)10.1 (9.3)  9.3 (9.0)  .048
    Medicare27.1 (15.2)27.7 (16.9)29.7 (14.6)28.6 (12.3)  .544
Practice oriented toward socioeconomically vulnerable populations, %
    Share of revenue from Medicaid in top quartile across practicesc27.322.330.816.0  .006
    Federally qualified health centerc22.627.418.011.1  .001
    Rural zip codec26.713.935.115.1<.001
Practice currently participates in a delivery system or payment reform initiative, %
    Primary care improvement programs43.666.659.457.0<.001
    Pay for performance52.775.763.868.1<.001
    Capitated commercial contracts31.653.847.349.3<.001
    Commercial ACO contract31.948.542.856.8<.001
    CMS Comprehensive Primary Care+c,f  .005
    Medicaid ACO contractc27.339.337.845.2<.001
Practice location by United States census region, %g
    Northeast19.617.425.611.6  .016
    South33.319.121.323.3  .009
    West28.241.616.825.6  .015
  • ACO = accountable care organization; CMS = Centers for Medicare and Medicaid Services; Med-Peds = Medicine-Pediatrics; NA = not applicable; OB-GYN = obstetrics-gynecology.

  • aOwnership structures: independent practices do not have any ownership relationships beyond the practice itself. Systems include medical group practices owned by an organization that owns other practices but no hospital, simple system practices owned by an organization that owns other practices and ≥1 hospital, and complex system practices owned by an organization that itself owns a medical group or another system (ie, a system within a system).

  • bDenotes independent variables included in models estimating adjusted predictors of difficulty obtaining care for children with behavioral health disorders (see Table 2). These comprise pre-determined independent variables (and model specifications) that were based on our hypotheses regarding practice ownership structure, Medicaid ACO participation, and a parsimonious set of controls in these descriptive cross-sectional models. Other practice attributes in Table 1 are offered for descriptive context only.

  • cDesign-based Wald c for categorical variables; F-statistic for continuous variables.

  • dOther clinicians could be any of the following: physician assistants, nurse practitioners, clinical nurse specialists, clinical social workers, counselors, marriage and family therapists, or psychologists but were most frequently physician assistants or nurse practitioners with further specification about the role they might be playing clinically.

  • eIncludes pediatric specialists who also prescribe psychotropic medications (eg, developmental-behavioral pediatricians, pediatric neurologists, neurodevelopmental pediatricians).

  • fVia CMS Comprehensive Primary Care Plus participation lists. Note that these practices overlap with practices reporting participation in primary care improvement programs.

  • gInstead of controlling for census region in models used to obtain adjusted estimates, we controlled for state in which the practice is located.