Healthy Life Expectancy Decomposition
Also known as: Health Expectancy Decomposition, Nusselder-Looman Decomposition, Decomposition of Disability-Free Life Expectancy, Mortality and Disability Decomposition of Health Expectancy
Healthy (or disability-free) life expectancy combines how long people live with how much of that life is spent in good health, and differences in it between groups or over time reflect two distinct forces: changes in mortality and changes in the prevalence of disability. Healthy-life-expectancy decomposition separates these forces. Building on the Sullivan method — which weights life-table person-years by the age-specific share of life lived without disability — Wilma Nusselder and Caspar Looman's 2004 method splits the gap in health expectancy between two populations into an additive mortality component and a disability component for each age, and can further attribute each to specific causes. This resolves the central interpretive ambiguity of health expectancy: a population can have higher healthy life expectancy because its people die later, because they are less disabled at each age, or both, and only a decomposition can tell which.
Key highlights
- Resolves the key ambiguity of health expectancy by separating the mortality (living longer) and disability (living healthier) channels of a difference.
- Additive and exact: the mortality and disability components sum to the observed gap in healthy life expectancy, enabling a complete accounting.
- Builds directly on the widely used Sullivan method and standard abridged life tables, so it uses data agencies already collect.
- Extends to a cause-of-death and cause-of-disability breakdown, supporting public-health priority setting between preventing death and preventing disability.
Intuition
This section is available to Pro members. Upgrade to Pro
How it works
This section is available to Pro members. Upgrade to Pro
When to use it
Use healthy-life-expectancy decomposition when two populations (groups, sexes, regions, or time points) differ in disability-free or self-rated-healthy life expectancy and you need to know whether the difference reflects mortality, morbidity, or both, and through which causes. It requires, for each population, an abridged life table and cross-sectional age-specific prevalence of the chosen health state, and the cause breakdown additionally needs cause-specific mortality and ideally cause-specific disability data. It is the natural extension when a plain life-expectancy decomposition is insufficient because the question concerns years of healthy life rather than total years. It inherits the cross-sectional assumptions of the Sullivan method and is descriptive rather than causal; for purely mortality-based gaps, the simpler life-expectancy decomposition suffices.
Strengths & limitations
- Resolves the key ambiguity of health expectancy by separating the mortality (living longer) and disability (living healthier) channels of a difference.
- Additive and exact: the mortality and disability components sum to the observed gap in healthy life expectancy, enabling a complete accounting.
- Builds directly on the widely used Sullivan method and standard abridged life tables, so it uses data agencies already collect.
- Extends to a cause-of-death and cause-of-disability breakdown, supporting public-health priority setting between preventing death and preventing disability.
- Inherits the Sullivan method's cross-sectional assumption: prevalence at a point in time stands in for a cohort's experience, which can bias estimates when disability trends are changing.
- Sensitive to how the health state (disability, activity limitation, self-rated health) is defined and measured, and to comparability of that definition across populations.
- Requires reliable age-specific prevalence data, which are often noisier and less standardized than mortality data.
- Descriptive, not causal, and the mortality/disability split depends on the choice of an averaged reference schedule, so apportionment at the margins is not unique.
Common pitfalls
This section is available to Pro members. Upgrade to Pro
Applications
This section is available to Pro members. Upgrade to Pro
Frequently asked
How is this different from the Sullivan method and from healthy life expectancy?
The Sullivan method and the healthy-life-expectancy page describe how to compute a single number — the years of life expected in good health — by weighting life-table person-years with disability prevalence. This page describes how to decompose a difference between two such numbers into a mortality part and a disability part, by age and cause. In short, Sullivan measures; this method explains. You compute Sullivan health expectancy for each population first, then apply the Nusselder-Looman decomposition to the gap.
Why separate the mortality and disability components at all?
Because the same difference in healthy life expectancy can arise from opposite underlying dynamics with opposite policy implications. A higher health expectancy driven by lower mortality means people live longer; driven by lower disability it means people live healthier; and falling mortality can even add disabled years. Nusselder and Looman's decomposition makes these channels explicit and additive, so analysts can distinguish compression of morbidity from mere postponement of death and target prevention of death or prevention of disability accordingly.
What are the main data and assumption caveats?
The method inherits Sullivan's cross-sectional assumption — point-in-time prevalence stands in for cohort experience — so it can mislead when disability is trending. It is also sensitive to how the health state is defined and to the comparability of disability measurement across the populations being compared. Prevalence data are typically noisier than mortality data, and the mortality/disability split uses an averaged reference schedule, so the exact apportionment is not unique. Results are descriptive and should be read as an accounting of where differences arise, not as causal effects.
Sources
- 1.Nusselder, W. J., & Looman, C. W. N. (2004). Decomposition of differences in health expectancy by cause. Demography, 41(2), 315-334.
- 2.Sullivan, D. F. (1971). A single index of mortality and morbidity. HSMHA Health Reports, 86(4), 347-354.
You have read it. What now?
Cite this page
ScholarGate. (2026, June 23). Healthy Life Expectancy Decomposition. ScholarGate. https://scholargate.app/social-epidemiology/healthy-life-expectancy-decomposition