Tipos de isotermas de adsorción

The importance of equity issues in relation to the effect of VPHI on the delivery of health care services may reasonably be argued to rest largely on the existence of some meaningful connection between the use of health care services and well-being (Glied 2008). Equity may be modelled as an externality where the access to and use of health care services by one person enters the utility of another. An equity externality

implies that people place some value on the degree of equality in the delivery of health care services.40 In

this relation, it is noted that a preference for equity is more than a just belief that everyone should have access to some health care, it implies that the difference in access to or use of health care services between the higher and the lower income groups should not exceed some maximum (Glied 2008).

As previously mentioned, the extent of equity in the delivery of health care services may be assessed based on the principle of horizontal equity, which implies that individuals in equal need have the same access to or use of health care services (Van Doorslaer and Wagstaff 1992). Considering horizontal

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Differences in the access to and the use of health care services caused by VPHI may also enter utility functions in other ways than through an equity externality, although these are less likely. For one thing, it is possible that the uninsured are envious of the VPHI purchase of others and that this reduces their welfare. Moreover, VPHI may also generate welfare for the privately insured due to pretentiousness or snob effects if they value their VPHI more simply because others cannot afford it (Dowd 1999).

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inequity as any differences, it may be argued that VPHI generates horizontal inequity in the access to health care between the privately insured and those not holding VPHI by definition, by allowing individuals with the same need for health care to differ in their access to treatment depending on insurance status. However, a more frequently used approach is to consider horizontal inequity as differences in access or use that vary systematically with sociodemographic determinants.

Empirical studies of the take-up of VPHI have consistently found this to increase with income and education level (see e.g. Besley et al. (1999), Grepperud and Iversen (2011), King and Mossialos (2005), Rodríguez and Stoyanova (2008), and Ellis and Savage (2008)). Partly because the better off and higher educated are more likely to purchase VPHI on an individual basis, and partly because they are more likely to have employers who purchase it on their behalf. The empirical evidence thus indicates that horizontal inequity in the access to health care services caused by VPHI is a real issue of concern.

The empirical evidence on whether VPHI generates horizontal inequity in the use of health care services is closely related to the literature on ex post moral hazard. As accounted for in section 3.3.2, ex post moral hazard is a question of whether VPHI causes individuals to use additional health care services for which the marginal cost exceeds the marginal benefit, i.e. inefficient overuse, whereas inequity focuses on overuse relative to the medical need for care. However, due to problems in measuring marginal benefits and costs, the empirical literature on inequity in use is largely identical with than on ex post moral hazard. In either case, the results of this literature are not clear-cut. While some studies have found that VPHI does not affect the overall use of health care services (e.g. Höfter (2006), Riphahn et al. (2003), and Schokkaert et al. (2010)), others found a positive and significant effect (e.g. Cameron et al. (1988), Harmon and Nolan (2001), and Savage and Wright (2003)). In addition, Mossialos and Thomson (2002) summarised the empirical evidence on VPHI in the European Union and found indications that patients with duplicate VPHI were treated favourably by physicians in Finland, Spain, and Portugal, and had shorter waiting times for treatment in Austria, Ireland, Italy, Portugal, Spain, Sweden, and the United Kingdom. Combined with the fact that the privately insured are generally better off, this points in the direction of duplicate VPHI generating some extent of horizontal inequity in the use of health care services.

Finally, it has been argued that VPHI does not give rise to particular equity issues for two different reasons. Firstly, it may be argued that high-income individuals can afford to use more of the health care services that are only partly covered by or excluded from the universal health care system than low- income individuals even in the absence of VPHI, and that they may also be able to purchase treatment at private hospitals or preferential treatment at public hospitals (White 2009). Hence, easier access for people with higher incomes would still exist in the absence of VPHI, assuming that there is a private market. Secondly, it may be argued that what matters is not equity but adequacy. According to this view, if the universal health care system is adequate, it is unproblematic that some individuals, i.e. the privately insured, have preferential access to health care and possibly also use more or a higher quality of some

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types of health care services, as long as they do not make anybody else worse off (Rodríguez and Stoyanova 2004). In most cases matters are, however, not quite so simple. For one thing, the ability to use the benefits of the universal health care system may be affected by whether individuals hold VPHI cf. the public moral hazard effects discussed in section 4.2.2.5. Second, duplicate VPHI may be argued to adversely affect the universal health care system in various ways, as discussed in section 4.2. Hence, the condition that nobody is made worse off by VPHI may not hold. Finally, it is noted that it adds an additional dimension to the equity discussion when VPHI premiums are subject to preferential tax treatment.