Primary care quality and cost for privately insured patients in and out of US Health Systems: Evidence from four states

Health Serv Res. 2020 Dec;55 Suppl 3(Suppl 3):1098-1106. doi: 10.1111/1475-6773.13590. Epub 2020 Oct 29.


Objective: To characterize physician health system membership in four states between 2012 and 2016 and to compare primary care quality and cost between in-system providers and non-system providers for the commercially insured population.

Data sources: Physician membership in health systems was obtained from a unique longitudinal database on health systems and matched at the provider level to 2014 all-payer claims data from Colorado, Massachusetts, Oregon, and Utah.

Study design: Using an observational study design, we compared physicians in health systems to non-system physicians located in the same state and geography on average cost of care (risk-adjusted using the Johns Hopkins' Adjusted Clinical Grouper), five HEDIS quality measures, one measure of developmental screening, and two Prevention Quality Indicator Measures.

Data collection/extraction methods: Patients in commercial health plans were attributed to a primary care physician accounting for the plurality of office visits. A cohort for each quality measure was constructed based on appropriate measure specifications.

Principal findings: The share of physicians in health systems increased steadily from 2012 to 2016 and ranged from 48% in Colorado to 63% in Utah in 2016. Compared to physicians not in a system, system physicians performed similarly on most HEDIS quality metrics compared to non-system physicians. Patients attributed to in-system physicians had about 40% higher rates (P < .05) of Ambulatory Care Sensitive Admissions (measured in admissions per 100 000:921.33 in-system vs 674.61 not-in-system for acute composite; 2540.91 in-system vs 1972.17 for chronic composite In-system providers were associated with $29 (P < .05) higher average per member per month costs (453.37 vs 432.93). Overall, differences in performance by system membership were relatively small compared to differences across states and geography.

Conclusion: A growing share of physicians is part of a health system from 2012 to 2016. Providers in health systems are not delivering primary care more efficiently than non-system providers for the commercially insured.

Keywords: cohort studies; geography; health care cost; ownership; primary care; quality of health care.

Publication types

  • Observational Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Female
  • Health Expenditures / statistics & numerical data
  • Health Services Research
  • Humans
  • Insurance, Health / statistics & numerical data*
  • Primary Health Care / economics
  • Primary Health Care / organization & administration*
  • Primary Health Care / standards
  • Private Sector / statistics & numerical data*
  • Quality Indicators, Health Care / statistics & numerical data
  • Quality of Health Care / statistics & numerical data*