# Leveraging Physician Networks to Improve Care and Outcomes for Low-Income Populations

> **NIH NIH R01** · YALE UNIVERSITY · 2020 · $515,989

## Abstract

Project Summary
Cardiovascular disease (CVD) remains one of the most prevalent diseases among the adult population and
disproportionately affects low-income populations. Medicaid, the primary source of health insurance for low-
income adults, plays a critical role in facilitating care for adults with CVD. Medicaid beneficiaries have
traditionally had difficulty obtaining timely access to specialists. To improve access to physicians and health
services, state Medicaid agencies have increasingly contracted with managed care organizations (MCO), who
in turn contract with networks of physicians to facilitate access to care. While regulations have standardized
the benefits, formularies, and cost sharing rules that plans must adhere to in Medicaid; MCOs have
considerable latitude to design and modify their physician networks. Consequently, the volume of cardiologists
and amount of physician turnover (churn) vary considerably across plans in the same market. We hypothesize
that these two features of networks, (1) network breadth and (2) network churn, are particularly impactful in
influencing patterns of care and outcomes for Medicaid managed care beneficiaries with CVD. Cardiac patients
in narrower networks may have to travel further, wait longer for appointments, and find a doctor they like from a
smaller set of options. Network churn may disrupt the relationships between patients with complex conditions
who are actively engaged in care and their primary care physicians or cardiologists. Although design of
physician networks directly influences how low-income populations access care for cardiovascular conditions,
there has been no investigation on how they impact the receipt of recommended care and outcomes. To date,
network adequacy regulations have been uninformed by the way that beneficiaries experience care and
disconnected from health care outcomes. Our objective, in this application, is to estimate the causal impact of
cardiovascular network design on health care outcomes for Medicaid patients with CVD. We propose to do this
via two innovations. First, we use a novel dataset which merges detailed physician network data with
administrative Medicaid data from several states. Second, we leverage the fact that a substantial fraction of
Medicaid enrollees that don't actively choose a plan are randomly-assigned to health plans, allowing us to
estimate the impact of physician network design on cardiovascular care and outcomes using a randomized-
controlled design, the gold standard in social science research. Specifically, our aims are to (1) Use patient
random- assignment to estimate the causal effect of network breadth on patterns of treatment, use and
outcomes for patients newly diagnosed with CVD, (2) Determine how physician exits impact patterns of
treatment, use and outcomes for patients with previously diagnosed (existing) CVD, and (3) Use simulation
models to inform adequacy standards for specialty physician networks of Medicaid MCOs. Our proje...

## Key facts

- **NIH application ID:** 9859452
- **Project number:** 5R01HL144644-02
- **Recipient organization:** YALE UNIVERSITY
- **Principal Investigator:** Chima Ndumele
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $515,989
- **Award type:** 5
- **Project period:** 2019-02-01 → 2022-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9859452

## Citation

> US National Institutes of Health, RePORTER application 9859452, Leveraging Physician Networks to Improve Care and Outcomes for Low-Income Populations (5R01HL144644-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9859452. Licensed CC0.

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