Cost-Effectiveness Analysis

Cost-effectiveness analysis (CEA) is a method of economic evaluation that compares the costs and health effects of alternative interventions, expressing the result as the extra cost required to gain an additional unit of health. By placing cost and benefit in a common framework, it helps inform decisions about how to allocate limited health resources for the greatest health gain.

Definition

Cost-effectiveness analysis is an economic evaluation that compares two or more interventions in terms of their costs and their health outcomes, summarising the trade-off as an incremental cost-effectiveness ratio — the difference in cost divided by the difference in health effect between alternatives.

Scope

This topic covers the logic and core elements of cost-effectiveness analysis: the comparison of alternatives, the incremental cost-effectiveness ratio, health outcome measures such as life-years and quality-adjusted life-years, the perspective and time horizon of an analysis, discounting, and the cost-effectiveness threshold used to interpret results. It is a methodological reference for appraising economic evaluations, not clinical or policy advice.

Core questions

• How are the costs and health effects of competing interventions compared in a single framework?
• What does the incremental cost-effectiveness ratio represent, and how is it interpreted?
• How are health outcomes measured, including the quality-adjusted life-year?
• How do perspective, time horizon, and discounting affect an analysis?
• How is a cost-effectiveness threshold used, and why is it contested?

Key concepts

• Incremental cost-effectiveness ratio (ICER)
• Quality-adjusted life-year (QALY)
• Life-years gained
• Cost-utility analysis
• Analytic perspective (e.g., health-system vs societal)
• Time horizon and discounting
• Cost-effectiveness threshold
• Sensitivity analysis and uncertainty

Key theories

Foundations of cost-effectiveness analysis

Weinstein and Stason set out the analytic foundations of CEA in health care, including incremental comparison of alternatives, the role of marginal cost and effect, and the principle of discounting future costs and health, establishing the framework later codified by expert panels.

Mechanisms

An analysis defines the alternatives being compared, the perspective from which costs and effects are counted, and the time horizon over which they accrue. Costs and health effects are measured for each option, and future values are discounted to present terms. The incremental cost-effectiveness ratio is computed as the difference in costs divided by the difference in health effects between an intervention and its comparator; when health is measured in quality-adjusted life-years, the analysis is a cost-utility analysis. The resulting ratio is interpreted against a threshold representing what a decision-maker is willing to pay for a unit of health gain, with sensitivity analysis used to test how robust the conclusion is to uncertainty in the inputs.

Clinical relevance

Cost-effectiveness evidence informs coverage and reimbursement decisions and the design of clinical guidelines by indicating which interventions deliver health gains worth their cost at the population level. It describes how value is assessed across alternatives and is not a tool for choosing care for an individual patient.

Evidence & guidelines

Methodological standards for CEA have been set by expert consensus, notably the first U.S. Panel on Cost-Effectiveness in Health and Medicine in the 1990s and its updated Second Panel, which issued recommendations on perspective, the reference case, measurement of effects, and reporting. These standards aim to make analyses comparable and transparent; many national agencies that appraise health technologies build on them.

History

Cost-effectiveness analysis was adapted to health care in the 1970s, with Weinstein and Stason's 1977 paper providing an influential statement of its foundations. The U.S. Panel on Cost-Effectiveness in Health and Medicine codified methods in 1996, and the Second Panel updated them in 2016, while the rise of health-technology assessment agencies internationally embedded CEA in coverage and pricing decisions.

Debates

Where should the cost-effectiveness threshold be set?

Interpreting an ICER requires a threshold for what a unit of health is worth, but there is no consensus on its level or whether a fixed threshold is appropriate, since it embodies value judgements about willingness to pay and opportunity cost.

Whose perspective and which costs should count?

Analyses can take a health-system or a broader societal perspective, and the choice changes which costs and benefits are included; the Second Panel recommended reporting both a health-system and a societal reference case to make this explicit.

Key figures

• Milton Weinstein
• Louise Russell
• Marthe Gold
• Peter Neumann
• Mark Sculpher

Seminal works

• weinstein-stason-1977
• russell-1996
• sanders-2016

Frequently asked questions

What is an incremental cost-effectiveness ratio?

It is the difference in cost between two interventions divided by the difference in their health effect — for example, the extra cost per additional quality-adjusted life-year gained. It summarises the trade-off between spending more and gaining more health.

What is a quality-adjusted life-year?

A QALY combines length of life and quality of life into a single measure, weighting each year lived by a value between 0 and 1 reflecting health-related quality of life, so that interventions affecting both survival and quality can be compared on a common scale.