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Did the HMO Revolution Cause Hospital Consolidation?


  • Robert Town
  • Douglas Wholey
  • Roger Feldman
  • Lawton R. Burns


During the 1990s US healthcare markets underwent a significant transformation. Managed care rose to become the dominant form of insurance in the private sector. Also, a wave of hospital consolidation occurred. In 1990, the mean population-weighted hospital Herfindahl-Hirschman Index (HHI) in a Health Services Area (HSA) was .19. By 2000, the HHI had risen to .26. This paper explores whether the rise in managed care caused the increase in hospital concentration. We use an instrumental variables approach with 10-year differences to identify the relationship between managed care penetration and hospital consolidation. Our results strongly imply that the rise of managed care did not cause the hospital consolidation wave. This finding is robust to a number of different specifications.

Suggested Citation

  • Robert Town & Douglas Wholey & Roger Feldman & Lawton R. Burns, 2005. "Did the HMO Revolution Cause Hospital Consolidation?," NBER Working Papers 11087, National Bureau of Economic Research, Inc.
  • Handle: RePEc:nbr:nberwo:11087
    Note: HC IO

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    References listed on IDEAS

    1. Hansen, Lars Peter, 1982. "Large Sample Properties of Generalized Method of Moments Estimators," Econometrica, Econometric Society, vol. 50(4), pages 1029-1054, July.
    2. Gaynor, Martin & Vogt, William B., 2000. "Antitrust and competition in health care markets," Handbook of Health Economics,in: A. J. Culyer & J. P. Newhouse (ed.), Handbook of Health Economics, edition 1, volume 1, chapter 27, pages 1405-1487 Elsevier.
    3. Werden, Gregory J., 1990. "The limited relevance of patient migration data in market delineation for hospital merger cases," Journal of Health Economics, Elsevier, vol. 8(4), pages 363-376, February.
    4. Newey, Whitney K., 1987. "Efficient estimation of limited dependent variable models with endogenous explanatory variables," Journal of Econometrics, Elsevier, vol. 36(3), pages 231-250, November.
    5. Daniel P. Kessler & Mark B. McClellan, 2000. "Is Hospital Competition Socially Wasteful?," The Quarterly Journal of Economics, Oxford University Press, vol. 115(2), pages 577-615.
    6. Douglas Staiger & James H. Stock, 1997. "Instrumental Variables Regression with Weak Instruments," Econometrica, Econometric Society, vol. 65(3), pages 557-586, May.
    7. Laurence C. Baker & Martin L. Brown, 1999. "Managed Care, Consolidation Among Health Care Providers, and Health Care: Evidence from Mammography," RAND Journal of Economics, The RAND Corporation, vol. 30(2), pages 351-374, Summer.
    8. Raymond Deneckere & Carl Davidson, 1985. "Incentives to Form Coalitions with Bertrand Competition," RAND Journal of Economics, The RAND Corporation, vol. 16(4), pages 473-486, Winter.
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    Cited by:

    1. Akosa Antwi Yaa & Gaynor Martin S & Vogt William B, 2009. "A Bargain at Twice the Price? California Hospital Prices in the New Millennium," Forum for Health Economics & Policy, De Gruyter, vol. 12(1), pages 1-23, July.
    2. Robert Town & Douglas Wholey & Roger Feldman & Lawton R. Burns, 2006. "The Welfare Consequences of Hospital Mergers," NBER Working Papers 12244, National Bureau of Economic Research, Inc.

    More about this item

    JEL classification:

    • I11 - Health, Education, and Welfare - - Health - - - Analysis of Health Care Markets
    • L12 - Industrial Organization - - Market Structure, Firm Strategy, and Market Performance - - - Monopoly; Monopolization Strategies

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