Journal of General Internal Medicine

, Volume 28, Issue 3, pp 459–465

Patient Sharing Among Physicians and Costs of Care: A Network Analytic Approach to Care Coordination Using Claims Data

  • Craig Evan Pollack
  • Gary E. Weissman
  • Klaus W. Lemke
  • Peter S. Hussey
  • Jonathan P. Weiner
Original Research



Improving care coordination is a national priority and a key focus of health care reforms. However, its measurement and ultimate achievement is challenging.


To test whether patients whose providers frequently share patients with one another—what we term ‘care density’—tend to have lower costs of care and likelihood of hospitalization.


Cohort study


9,596 patients with congestive heart failure (CHF) and 52,688 with diabetes who received care during 2009. Patients were enrolled in five large, private insurance plans across the US covering employer-sponsored and Medicare Advantage enrollees


Costs of care, rates of hospitalizations


The average total annual health care cost for patients with CHF was $29,456, and $14,921 for those with diabetes. In risk adjusted analyses, patients with the highest tertile of care density, indicating the highest level of overlap among a patient’s providers, had lower total costs compared to patients in the lowest tertile ($3,310 lower for CHF and $1,502 lower for diabetes, p < 0.001). Lower inpatient costs and rates of hospitalization were found for patients with CHF and diabetes with the highest care density. Additionally, lower outpatient costs and higher pharmacy costs were found for patients with diabetes with the highest care density.


Patients treated by sets of physicians who share high numbers of patients tend to have lower costs. Future work is necessary to validate care density as a tool to evaluate care coordination and track the performance of health care systems.


care coordination performance measure provider social networks care density 

Supplementary material

11606_2012_2104_MOESM1_ESM.docx (48 kb)
ESM 1(DOCX 47 kb)

Copyright information

© Society of General Internal Medicine 2012

Authors and Affiliations

  • Craig Evan Pollack
    • 1
    • 2
  • Gary E. Weissman
    • 3
  • Klaus W. Lemke
    • 2
  • Peter S. Hussey
    • 4
  • Jonathan P. Weiner
    • 2
  1. 1.Johns Hopkins University School of MedicineBaltimoreUSA
  2. 2.Johns Hopkins Bloomberg School of Public HealthBaltimoreUSA
  3. 3.Internal Medicine Residency ProgramHospital of the University of PennsylvaniaPhiladelphiaUSA
  4. 4.RAND CorporationArlingtonUSA

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