Concept Architecture
Concept
Theoretically, Healthy Year Equivalent is a preference-based measure of health outcome that represents the number of years lived in perfect health that an individual considers equivalent to a specified sequence of health states over time. It was developed as an alternative to the Quality-Adjusted Life Year (QALY) to accommodate preferences for the timing and distribution of health states that may violate the assumptions of additive independence underlying QALYs. The concept exists to capture overall preferences for complete health profiles rather than valuing each health state independently.
Mathematically, the healthy year equivalent is determined by identifying the duration of life in perfect health that yields the same utility as the health profile being evaluated. The mathematical framework is based on utility equivalence rather than the additive multiplication of utility weights by time. Estimation requires elicitation of preferences for entire health trajectories using established utility assessment methods.
In practice, healthy year equivalents are estimated through direct preference elicitation techniques such as the standard gamble or time trade-off applied to complete health profiles. Respondents compare alternative health trajectories with varying durations of perfect health until indifference is achieved. Although historically important in health economics, the measure has been used less frequently than the QALY because of the complexity of preference elicitation and analysis.
Purpose
Used to value complete health trajectories, evaluate preferences that extend beyond additive health utility models, compare alternative health outcomes, and assess interventions where the timing and sequence of health states influence overall preferences.
Mathematical Formulae
Primary Formula
The healthy year equivalent is defined by the utility equivalence condition:
U(H) = U(HYE)
where:
- U(H) = utility of the health profile
- U(HYE) = utility of the equivalent number of years lived in perfect health
Supporting Formulae
There is no universally recognised canonical mathematical formula.
Related Mathematical Methods
- Utility theory
- Standard gamble
- Time trade-off
- Preference elicitation
- Health state valuation
Example
A respondent evaluates a treatment that produces five years with varying health states following surgery. Through a standard gamble exercise, the respondent indicates that this health profile is equally desirable as living 3.8 years in perfect health. The Healthy Year Equivalent for the treatment outcome is therefore 3.8 healthy years.
Excel Implementation
| Function | Example Formula | Health Economics Application |
|---|---|---|
| IF | =IF(B2=C2,""Equivalent"",""Not Equivalent"") | Identify the point of utility equivalence during preference elicitation |
| INDEX | =INDEX(A2:A20,MATCH(TargetUtility,B2:B20,1)) | Determine the healthy year equivalent corresponding to the elicited utility |
| MATCH | =MATCH(TargetUtility,B2:B20,1) | Locate the utility equivalence point |
| Goal Seek | Goal Seek | Identify the duration of perfect health that produces utility equivalence |
VBA (Optional)
Automate iterative utility-equivalence calculations for Healthy Year Equivalent estimation across multiple respondents and health profiles.
Sources
- Mehrez A, Gafni A. Healthy-Years Equivalents versus Quality-Adjusted Life Years: In Pursuit of Progress. Medical Decision Making. 1989.
- Mehrez A, Gafni A. Quality-Adjusted Life Years, Utility Theory, and Healthy-Years Equivalents. Medical Decision Making. 1991.
- Torrance GW. Measurement of Health State Utilities for Economic Appraisal. Journal of Health Economics. 1986.
- Drummond MF, Sculpher MJ, Claxton K, Stoddart GL, Torrance GW. Methods for the Economic Evaluation of Health Care Programmes. Oxford University Press.
- Gold MR, Stevenson D, Fryback DG. HALYs and QALYs and DALYs, Oh My: Similarities and Differences in Summary Measures of Population Health. Annual Review of Public Health. 2002.
Related Concepts (2)
Library
Publications
1
Measuring and Valuing Health Benefits for Economic Evaluation — Brazier, Ratcliffe, Salomon & Tsuchiya, 2nd Edition ed., 2017 (Oxford University Press)
The comprehensive text on the measurement and valuation of health benefits for economic evaluation — defining health, valuation techniques (time trade-off, standard gamble), whose values to use, preference-based measures (EQ-5D, SF-6D), and the construction of QALYs.
BookView source →
Frequently Asked Questions (7)
What is a healthy year equivalent?
An alternative to the QALY deriving its valuations directly from a sequence of health states over a lifetime, rather than combining separate utility values.
Source: Mehrez & Gafni 1989
What is a healthy-year equivalent?
A healthy-year equivalent, or HYE, is an alternative to the QALY that derives its valuation directly from a person's whole sequence of health states over a lifetime, rather than combining separate utility values for individual states. Proposed by Mehrez and Gafni, it expresses a health profile as the number of years in full health regarded as equivalent to it. The aim was a measure resting on firmer theoretical foundations than the QALY, capturing the valuation of an entire lifetime health path at once.
Source: Mehrez & Gafni 1989
What single-number health outcome is a healthy-year equivalent?
A healthy-year equivalent is an outcome measure expressing a person's health path as the number of years in full health regarded as equivalent to it. It is derived from a two-stage preference elicitation intended to capture attitudes to health and to risk more fully than a single quality weight. The measure was put forward as an alternative to the quality-adjusted life year, aiming to reflect the whole profile of health over time rather than one static state. It gives a single figure that stands for an entire sequence of health experiences.
Source: Mehrez and Gafni 1989
How does the healthy-year equivalent differ from the QALY?
The healthy-year equivalent differs from the QALY in how it values health over time. The QALY values each health state separately by a utility and multiplies by time spent, then sums across states, so the whole is built from parts. The HYE values the entire sequence of health states over a lifetime directly, as one profile, yielding the equivalent number of healthy years. Mehrez and Gafni argued this whole-profile valuation avoids restrictive assumptions the QALY makes in combining separate state utilities.
Source: Mehrez & Gafni 1989
How is a healthy-year equivalent measured?
A healthy-year equivalent is measured by eliciting a person's valuation of an entire health profile, the sequence of states they experience over time, and expressing it as the number of years in full health they would regard as equivalent. Mehrez and Gafni proposed a two-stage procedure using the standard gamble applied to the whole profile. Because it values the lifetime path as a whole, the elicitation is more demanding than valuing single states, which is one reason the HYE is used less than the QALY.
Source: Mehrez & Gafni 1989
Why was the healthy-year equivalent proposed?
The healthy-year equivalent was proposed to provide a measure of health outcome on firmer theoretical foundations than the QALY. Mehrez and Gafni argued that the QALY, in building a total from separately valued states multiplied by time, relies on restrictive assumptions about preferences that may not hold, such as constant value of a health state independent of its duration and context. By valuing the whole health profile directly, the HYE was intended to represent individual preferences over lifetime health more faithfully.
Source: Mehrez & Gafni 1989
What are the limitations of the healthy-year equivalent?
The healthy-year equivalent has limitations that have kept its use limited. Valuing an entire lifetime health profile directly is demanding to elicit and impractical for the many profiles an analysis may involve. Debate has questioned whether the HYE truly rests on firmer foundations than the QALY or offers a practical advantage, and whether its claimed theoretical superiority holds. As a result, despite its conceptual interest, the HYE is used far less than the QALY in economic evaluation.
Source: Mehrez & Gafni 1989
Trust Record
Verified by Dr Darrin Baines
British health economist
Professional identity: darrinbaines.org
Verification date: 17 Sep 2025
Content version: 1.0.0
Canonical Identity
- Term code
- HE-EE-QALY-004
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