Cost-benefit analysis (CBA) is a recognised as the economic evaluation technique that accords
most with the underlying principles of standard welfare economic theory. However, due to problems
associated with the technique, economists evaluating resources allocation decisions in health
care have most often used cost-effective analysis (CEA), in which health benefits are expressed in
non-monetary units. As a result, attempts have been made to build a welfare economic bridge
between cost-benefit analysis (CBA) and cost-effectiveness analysis (CEA). In this paper, we
develops these attempts and finds that, while assumptions can be made to facilitate a constant
willingness-to-pay per unit of health outcome, these restrictions are highly unrealistic. We develop
an impossibility theorem that shows it is not possible to link CBA and CEA if: (i) the axioms of
expected utility theory hold; (ii) the quality-adjusted life-year (QALY) model is valid in a welfare
economic sense; and (iii) illness affects the ability to enjoy consumption. We conclude that, within
a welfare economic framework, it would be unwise to rely on a link between CBA and CEA in
economic evaluations