[Cost-benefit principle and cost containment].

Benefits-in-kind and co-payment are often regarded as instruments to support self-responsible demand of the insured and to generate effective cost control. Economic theory however assumes that benefits-in-kind alone (without co-payment) will not have a great influence on the demand decision of the insured, because with rational behaviour price is not a determinant of demand. Also the control effects of (limited) co-payment are to be regarded as rather low. According to the hypothesis of supplier induced demand the major influence on demand is generated by those providing health care services, as soon as the patient has made up the decision to visit a doctor. But co-payment determines the decision and the timing of the initial contact, resulting in potentially negative effects on medical outcome. This is especially true, if co-payment ist not moderated by social policy. These theoretical considerations are supported by empirical evidence provided by the example of the French ambulatory care sector.