Institutional members access full text with Ovid®

Share this article on:

Access is Not Enough: Characteristics of Physicians Who Treat Medicaid Patients

Geissler, Kimberley H. PhD; Lubin, Benjamin PhD; Marzilli Ericson, Keith M. PhD

doi: 10.1097/MLR.0000000000000488
Original Articles

Background: Access to physicians is a major concern for Medicaid programs. However, little is known about relationships between physician participation in Medicaid and the individual-level and practice-level characteristics of physicians.

Methods: We used the 2011 Massachusetts All Payer Claims Database, containing all commercial and Medicaid claims; we linked with data on physician characteristics. We measured Medicaid participation intensity (fraction of the physician’s patient panel with Medicaid) for primary care physicians (PCPs) and medical specialists. We measured influence of physicians within a patient referral network using eigenvector centrality. We used regression models to associate Medicaid intensity with physician individual-level and practice-level characteristics.

Findings: About 92.6% of physicians treated at least 1 Medicaid patient, but the median physician’s panel contained only 5.7% Medicaid patients. Medicaid intensity was associated with physician training and influence for PCPs and specialists. For medical specialists, a 1 percentage point increase in Medicaid intensity was associated with a lower probability of being board certified (−0.22 percentage points; 95% CI, −0.30, −0.14), lower probability of attending a domestic medical school (−0.14 percentage points; 95% CI, −0.22, −0.05), having attended a less well-ranked domestic medical school (0.23 ranks; 95% CI, 0.15, 0.30), and having slightly less influence in the referral network. PCPs displayed similar results but high Medicaid intensity physicians had substantially less influence in the referral network.

Conclusions: Medicaid participation intensity shows substantial variation across physicians, indicating limits of binary participation measures. Physicians with more Medicaid patients had characteristics often perceived by patients to be of lower quality.

Supplemental Digital Content is available in the text.

*University of Massachusetts—Amherst School of Public Health and Health Sciences, Amherst

Questrom School of Business, Boston University, Boston

National Bureau of Economic Research, Cambridge, MA

Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Website,

Supported by a research grant from the National Institute of Health Care Management (NIHCM) Foundation and by the Boston University Questrom School of Business.

The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIHCM Foundation.

An earlier version of this work was presented as a poster presentation at the 2015 AcademyHealth Annual Research Meeting.

The authors declare no conflict of interest.

Reprints: Kimberley H. Geissler, PhD, University of Massachusetts—Amherst School of Public Health and Health Sciences, 325 Arnold House, 715 North Pleasant Street, Amherst, MA 01003. E-mail:

Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.