Social Science & Medicine

The Diffusion of Health Care Fraud: A Network Analysis

Social Science & Medicine

A. James O’Malley, Thomas A. Bubolz, Jonathan S. Skinner

Many studies have examined the diffusion of health care innovations but less is known about the diffusion of health care fraud. In this paper, we consider the diffusion of potentially fraudulent Medicare home health care billing in the United States during 2002-16, with a focus on the 21 hospital referral regions (HRRs) covered by local Department of Justice anti-fraud “strike force” offices. We hypothesize that patient-sharing across home health care agencies provides a mechanism for the rapid diffusion of fraudulent strategies; we measure such activity using a novel bipartite mixture (or BMIX) network index. First, we find a remarkable increase in home health care activity between 2002 and 2009 in some but not all regions; average billing per Medicare enrollees in McAllen TX and Miami increased by $2,127 and $2,422 compared to a $289 increase in other HRRs not targeted by the Department of Justice. Second, we establish that the HRR-level BMIX (but not other network measures) was a strong predictor of above-average home care expenditures across HRRs. Third, within HRRs, agencies sharing more patients with other agencies were predicted to increase spending the following year. Finally, the initial 2002 BMIX index was a strong predictor of subsequent changes in HRR-level home health billing during 2002-9. These results highlight the importance of bipartite network structure in diffusion and in infection models more generally.

READ MORE

The Diffusion of Health Care Fraud: A Network Analysis

NBER Working Paper

A. James O’Malley, Thomas A. Bubolz, Jonathan S. Skinner

Many studies have examined the diffusion of health care innovations but less is known about the diffusion of health care fraud. In this paper, we consider the diffusion of potentially fraudulent Medicare home health care billing in the United States during 2002-16, with a focus on the 21 hospital referral regions (HRRs) covered by local Department of Justice anti-fraud “strike force” offices. We hypothesize that patient-sharing across home health care agencies provides a mechanism for the rapid diffusion of fraudulent strategies; we measure such activity using a novel bipartite mixture (or BMIX) network index. First, we find a remarkable increase in home health care activity between 2002 and 2009 in some but not all regions; average billing per Medicare enrollees in McAllen TX and Miami increased by $2,127 and $2,422 compared to a $289 increase in other HRRs not targeted by the Department of Justice. Second, we establish that the HRR-level BMIX (but not other network measures) was a strong predictor of above-average home care expenditures across HRRs. Third, within HRRs, agencies sharing more patients with other agencies were predicted to increase spending the following year. Finally, the initial 2002 BMIX index was a strong predictor of subsequent changes in HRR-level home health billing during 2002-9. These results highlight the importance of bipartite network structure in diffusion and in infection models more generally.

READ MORE

Measuring racial segregation in health system networks using the dissimilarity index

Social Science & Medicine
Austin AM, Carmichael DQ, Bynum JPW, Skinner JS.

Racial disparities in the end-of-life treatment of patients are a well observed fact of the U.S. healthcare system. Less is known about how the physicians treating patients at the end-of-life influence the care received. Social networks have been widely used to study interactions with the healthcare system using physician patient-sharing networks. In this paper, we propose an extension of the dissimilarity index (DI), classically used to study geographic racial segregation, to study differences in patient care patterns in the healthcare system. Using the proposed measure, we quantify the unevenness of referrals (sharing) by physicians in a given region by their patients' race and how this relates to the treatments they receive at the end-of-life in a cohort of Medicare fee-for-service patients with Alzheimer's disease and related dementias. We apply the measure nationwide to physician patient-sharing networks, and in a sub-study comparing four regions with similar racial distribution, Washington, DC, Greenville, NC, Columbus, GA, and Meridian, MS. We show that among regions with similar racial distribution, a large dissimilarity index in a region (Washington, DC DI = 0.86 vs. Meridian, MS DI = 0.55), which corresponds to more distinct referral networks for black and white patients by the same physician, is correlated with black patients with Alzheimer's disease and related dementias receiving more aggressive care at the end-of-life (including ICU and ventilator use), and less aggressive quality care (early hospice care).

READ MORE