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Wong, Herbert

Authors: Zhan C, Miller MR, Wong H, et al.
Title: The effects of HMO penetration on preventable hospitalizations.
Publication: Health Serv Res 39(2):345-61.
Date: 2004
Abstract: Available on PubMed®
Topics: Access, Hospitals, Managed Care

Authors: Wong H., Hellinger F.
Title: Conducting Research on the Medicare Market: The Need for Better Data and Methods.
Publication: Health Serv Res 36(1 Part 2):291-308.
Date: 2001
Abstract: This study highlights data limitations, the need to improve data collection, the need to develop better analytic methods, and the need to use alternative data sources to conduct research related to the Medicare program. These objectives are achieved by reviewing existing studies on risk selection in Medicare HMOs, examining their data limitations, and introducing a new approach that circumvents many of these shortcomings. Data for 1995-97 for five States (Arizona, Florida, Massachusetts, New York, and Pennsylvania) from the HCUP State Inpatient Databases (SID), maintained by AHRQ and the Health Care Financing Administration's Medicare Managed Care Market Penetration Data Files and Medicare Provider Analysis and Review Files are used in this study. The authors analyzed hospital utilization rates for Medicare beneficiaries in the traditional fee-for-service Medicare and Medicare HMO sectors and examine the relationship between these rates and the Medicare HMO penetration rates. Medicare HMOs were found to have lower hospital utilization rates than their fee-for-service counterparts, differences in utilization rates vary across States, and that HMO penetration rates are inversely related to the rough measure of favorable selection. The authors conclude that substantial growth in Medicare HMO enrollment and the implementation of a new risk-adjusted payment system have led to an increasing need for research on the Medicare program. Improved data collection, better methods, new creative approaches, and alternative data sources are needed to address these issues in a timely and suitable manner.
Topics: Managed Care, Markets, Medicare.

Authors: Brooks JM, McClellan M, Wong HS.
Title: The marginal benefits of invasive treatments for acute myocardial infarction: Does insurance coverage matter?
Publication: Inquiry 37(1):75-90.
Date: 2000
Abstract: This paper applies instrumental variable (IV) techniques and estimates the average benefits of invasive surgical treatments for marginal acute myocardial infarction (AMI) patients by insurance coverage (i.e., Medicare, Medicaid, privately-insured non-HMO, privately-insured HMO, and self-pay) using data from Healthcare Cost and Utilization Project (HCUP), State Inpatient Database for the State of Washington, for 1988-93. The authors observed differences in average benefits for marginal patients across insurance subpopulations that cannot be explained by differences in measured clinical circumstances. The empirical results show that the insurance subpopulation with the greatest estimated marginal benefits are those with the lowest expected payment generosity to providers. Because of the relatively weak explanatory power of the instruments for three insurance subpopulations and because many of the parameter estimates across the insurance subpopulations are not statistically different from each other, policy recommendations should be approached cautiously, according to the authors. While more precise estimates are needed to make policy recommendations, application of IV estimation techniques to AMI patients demonstrates the usefulness of this approach to estimate treatment effects across patient populations (e.g., across types of insurance coverage) for medical conditions of interest to policymakers. These estimates may help determine whether treatments are over- or underutilized.
Topics: Hospitals, Insurance.
Availability: AHRQ Publication No. 00-R039 is available from the AHRQ Publications Clearinghouse.

Author: Hellinger FJ, Wong HS.
Title: Selection bias in HMOs: A review of the evidence.
Publication: Med Care Res Rev 57(4):405-39.
Date: 2000
Abstract: Many studies have examined the characteristics of persons who join HMOs to those of persons who join FFS plans, and several studies have reviewed findings regarding selection bias in HMOs. This article extends the findings of previous reviews by including information from studies published through 1999. This is important because of the rapid diffusion of HMOs in all markets and recent changes in the way public programs are organizing and paying for care from HMOs. This article also examines recent changes in how HMOs are paid. This is important because recent changes in payment methodologies may reduce, or eliminate, overpayments to HMOs resulting from selection bias. For example, changes in Medicare's risk adjustment system implemented in January 2000 unquestionably mitigate the impact of favorable selection on HMO payments.
Topics: Cost, Managed Care, Medicare.
Availability: AHRQ Publication No. 01-R026 is available from the AHRQ Publications Clearinghouse.

Authors: Fraser I, Wong H, Arent J, et al.
Title: Building Bridges IV: Managed care research comes of age.
Publication: Med Care Res Rev 56(Suppl 2):5-12.
Date: 1999
Abstract: This article describes and contrasts the challenges and objectives facing attendees of the May 1998 conference, "Building Bridges IV: Improving the Public's Health through Research Partnerships," with those facing conference attendees of the inaugural Building Bridges conference held in April 1995. The conference was cosponsored by the American Association of Health Plans, AHCPR, Centers for Disease Control, and HMO Research Network. A brief overview of the articles presented in the special issue of Med Care Res Rev demonstrates just how far managed care research has evolved. Five of the most notable changes since the first Building Bridges conference are highlighted: (1) The two worlds of managed care and research are no longer distinct and separate. (2) The conference and the parties to the dialogue have grown substantially. (3) We have moved from broad concern about the impact of managed care to looking inside the black box. (4) Researchers are questioning established theories about how markets do and will work, with particular emphasis on the role of consumers and purchasers. (5) Continued progress in conducting and implementing managed care research will require new bridges and partnerships.
Topics: Managed Care, Research Agenda.

Authors: Wong H, Smithen L.
Title: A case study of point-of-service medical use in a managed care plan.
Publication: Med Care Res Rev 56(Suppl 2):85-110.
Date: 1999
Abstract: This study examines the extent of point-of-service use in a managed care plan using 1990 and 1991 proprietary claims data (excluding pharmacy claims) from a large, well-established IPA with a point-of-service option. Our results show that approximately 12 percent of all claims were made by out-of-network providers, representing about 9 percent of the dollar value of all claims. This is about $131 per enrollee per year. While younger enrollees (i.e., 6-24 years) use fewer medical resources than do older enrollees, they tend to receive a greater share of their medical services from out-of-network providers. There is little difference between point-of-service use by males and females. Mental illness is the most common diagnosis for out-of-network claims, accounting for about 25 percent of the dollar value of out-of-network claims. 96 percent of the out-of-network claims for this diagnosis category were made by providers with a specialty in psychiatry.
Topics: Managed Care, Mental Health.

Authors: Brooks J, Dor A, Wong H.
Title: Hospital-insurer bargaining: An empirical investigation of appendectomy pricing.
Publication: Journal of Health Economics 16:417-34.
Date: 1997
Abstract: Employers' increased sensitivity to health care costs has forced insurers to seek ways to lower costs through effective bargaining with providers. What factors determine the prices negotiated between hospitals and insurers? The hospital-insurer interaction is captured in the context of a bargaining model, in which the gains from bargaining are explicitly defined. Appendectomy was chosen because it is a well defined procedure with little clinical variation. The authors' results show that certain hospitals' institutional arrangements (e.g., hospital affiliations), HMO penetration, and greater hospital concentration improve hospitals' bargaining position. Furthermore, hospitals' bargaining effectiveness has diminished over time and varies across States.
Topics: Cost, Hospitals, Insurance, Markets, Purchasing.
Availability: AHCPR Publication No. 97-R089 is available from the AHRQ Publications Clearinghouse.

Authors: Brooks J, Dor A, Wong H.
Title: The impact of physician payments on hospital-insurer bargaining in the U.S.
Publication: In Governments and Health Systems: Implications of Differing Involvements, edited by Chinitz D, Cohen J. New York (NY): John Wiley and Sons, Ltd.
Date: 1997
Abstract: While there has been considerable research on the impact of hospital competition on the insurers' ability to extract price discounts from hospitals, the role physicians play in the hospital-insurer bargaining process has been largely ignored. The hospital-insurer interaction can be thought of as a two-player bargaining game in which financial pressures from physicians can alter incentives. An application of the Nash-bargaining game leads to an empirical specification of hospital pricing in which payments to physicians are explicitly recognized. The authors' results show that certain hospital institutional arrangements (e.g., ownership type and hospital affiliations) and greater hospital concentration improve hospitals bargaining position. Although the new estimation strategy does effect the results somewhat, they provide added confidence to the notion that price competition is on the rise among U.S. hospitals.
Topics: Hospitals, Insurance, Markets.

Authors: Dor A, Duffy S, Wong H.
Title: Expense preference behavior and contract-management: Evidence from U.S. hospitals.
Publication: Southern Economic Journal 64(2):542-54.
Date: 1997
Abstract: This article reports on a study of expense preference behavior in a conditional sample of hospitals (before and after adoption of contract-management arrangements), using an extension of Mester's (1989) test. Expense preference theory maintains that managers of firms that possess market power and in which ownership is separate from control will employ an input mix that deviates from the cost minimizing input mix. Based on this test, contract managers do not appear to be cost minimizers, although they tend to exhibit lower expense preference behavior than salaried managers.
Topics: Cost, Hospitals, Markets, Methods.

Authors: Miller M, Welch W, Wong H.
Title: Exploring the relationship between inpatient facility and physician services.
Publication: Med Care 1997;35(2):114-27.
Date: 1997
Abstract: Available on PubMed®
Topics: Hospitals, Markets, Medicare.
Availability: AHCPR Publication No. 97-R045 is available from the AHRQ Publications Clearinghouse.

Author: Wong H.
Title: Market structure and the role of consumer information in the physician services industry: An empirical test.
Publication: Journal of Health Economics 15:139-60.
Date: 1996
Abstract: This article uses the Panzar and Rosse econometric test of market structure to evaluate the market for physician services. The article tests the hypothesis that an increase in the number of physicians causes consumer "informational confusion."
Topics: Markets, Methods.
Availability: AHCPR Publication No. 97-R005 is available from the AHRQ Publications Clearinghouse.

Current as of February 2003

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