Incremental cost effectiveness evaluation in clinical research.

Abstract

OBJECTIVE: The health economic evaluation of therapeutic and diagnostic strategies is of increasing importance in clinical research. Therefore also clinical trialists have to involve health economic aspects more frequently. However, whereas they are quite familiar with classical effect measures in clinical trials, the corresponding parameters in health economic evaluation of therapeutic and diagnostic procedures are still not this common. METHODS: The concepts of incremental cost effectiveness ratios (ICERs) and incremental net health benefit (INHB) will be illustrated and contrasted along the cost effectiveness evaluation of cataract surgery with monofocal and multifocal intraocular lenses. ICERs relate the costs of a treatment to its clinical benefit in terms of a ratio expression (indexed as Euro per clinical benefit unit). Therefore ICERs can be directly compared to a pre-specified willingness to pay (WTP) benchmark, which represents the maximum costs, health insurers would invest to achieve one clinical benefit unit. INHBs estimate a treatment's net clinical benefit after accounting for its cost increase versus an established therapeutic standard. Resource allocation rules can be formulated by means of both effect measures. RESULTS: Both the ICER and the INHB approach enable the definition of directional resource allocation rules. The allocation decisions arising from these rules are identical, as long as the willingness to pay benchmark is fixed in advance. Therefore both strategies crucially call for a priori determination of both the underlying clinical benefit endpoint (such as gain in vision lines after cataract surgery or gain in quality-adjusted life years) and the corresponding willingness to pay benchmark. CONCLUSION: The use of incremental cost effectiveness and net health benefit estimates provides a rationale for health economic allocation discussions and founding decisions. It implies the same requirements on trial protocols as yet established for clinical trials, that is the a priori definition of primary hypotheses (formulated as an allocation rule involving a pre-specified willingness to pay benchmark) and the primary clinical benefit endpoint (as a rationale for effectiveness evaluation).