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Co-payment systems in health care; between moral hazard and risk reduction


  • Ed Westerhout


  • Kees Folmer



It is well-known that co-payments in health insurance may increase social welfare by reducing moral hazard. Considerably less is known about the form co-payment schemes should ideally take. This paper investigates what co-payment rate and co-payment maximum characterize the optimal scheme, i.e. the scheme that achieves the highest level of social welfare, within the class of two-part co-payment schemes of which the second part features a zero rate. It also quantifies the welfare losses that correspond with sub-optimal co-payment schemes. The paper uses a model with optimizing households that are risk-averse, exercise price-elastic demand and are aware of the kinks in their budget constraints. Numerical simulations with this model indicate that the optimal scheme combines a 80% rate with a maximum of about 600 euro. Sensitivity analysis shows that the maximum varies a lot with changes in basic parameters; the 80% value for the optimal co-payment rate is quite robust, though. The welfare losses that correspond to alternative co-payment schemes are generally quite small.

Suggested Citation

  • Ed Westerhout & Kees Folmer, 2007. "Co-payment systems in health care; between moral hazard and risk reduction," CPB Discussion Paper 78, CPB Netherlands Bureau for Economic Policy Analysis.
  • Handle: RePEc:cpb:discus:78

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    References listed on IDEAS

    1. J. A. Mirrlees, 1971. "An Exploration in the Theory of Optimum Income Taxation," Review of Economic Studies, Oxford University Press, vol. 38(2), pages 175-208.
    2. Feldstein, Martin S, 1973. "The Welfare Loss of Excess Health Insurance," Journal of Political Economy, University of Chicago Press, vol. 81(2), pages 251-280, Part I, M.
    3. Blomqvist, Ake, 1997. "Optimal non-linear health insurance," Journal of Health Economics, Elsevier, vol. 16(3), pages 303-321, June.
    4. Feenberg, Daniel & Skinner, Jonathan, 1994. "The Risk and Duration of Catastrophic Health Care Expenditures," The Review of Economics and Statistics, MIT Press, vol. 76(4), pages 633-647, November.
    5. Sandmo, Agnar, 1987. "A Reinterpretation of Elasticity Formulae in Optimum Tax Theory," Economica, London School of Economics and Political Science, vol. 54(213), pages 89-96, February.
    6. Zweifel, Peter & Manning, Willard G., 2000. "Moral hazard and consumer incentives in health care," Handbook of Health Economics,in: A. J. Culyer & J. P. Newhouse (ed.), Handbook of Health Economics, edition 1, volume 1, chapter 8, pages 409-459 Elsevier.
    7. Manning, Willard G. & Marquis, M. Susan, 1996. "Health insurance: The tradeoff between risk pooling and moral hazard," Journal of Health Economics, Elsevier, vol. 15(5), pages 609-639, October.
    8. Wedig, Gerard J., 1988. "Health status and the demand for health : Results on price elasticities," Journal of Health Economics, Elsevier, vol. 7(2), pages 151-163, June.
    9. Feldman, Roger & Dowd, Bryan, 1991. "A New Estimate of the Welfare Loss of Excess Health Insurance," American Economic Review, American Economic Association, vol. 81(1), pages 297-301, March.
    10. Rosett, Richard N & Huang, Lien-fu, 1973. "The Effect of Health Insurance on the Demand for Medical Care," Journal of Political Economy, University of Chicago Press, vol. 81(2), pages 281-305, Part I, M.
    11. Raviv, Artur, 1979. "The Design of an Optimal Insurance Policy," American Economic Review, American Economic Association, vol. 69(1), pages 84-96, March.
    12. Gerdtham, Ulf-G. & Jonsson, Bengt, 1994. "Health care expenditure in the Nordic countries," Health Policy, Elsevier, vol. 26(3), pages 207-220, January.
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    More about this item

    JEL classification:

    • D60 - Microeconomics - - Welfare Economics - - - General
    • H21 - Public Economics - - Taxation, Subsidies, and Revenue - - - Efficiency; Optimal Taxation
    • I18 - Health, Education, and Welfare - - Health - - - Government Policy; Regulation; Public Health

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