Measuring Healthspan vs Lifespan

Lifespan is easy to measure: how long you live. Healthspan is harder and arguably more important: how long you live in good health, free of significant disease and disability. The gap between the two is where a lot of late-life suffering lives, and it is widening.

A 2024 cross-sectional study in JAMA Network Open analyzed all 183 World Health Organization member states and put a number on it: across 2000–2019, the global gap between life expectancy and healthy life expectancy grew from 8.5 to 9.6 years. In other words, the average person now spends nearly a decade alive but burdened by disease or disability, and gains in longevity are outpacing gains in health.

Why the distinction matters

Extending lifespan without extending healthspan means adding years of frailty and chronic illness rather than years of vitality. The same study found the gap is larger for women than men (by a mean of 2.4 years) and largest of all in the United States, at 12.4 years, driven by the rising burden of noncommunicable disease.

Across 183 countries, the world added years of life faster than it added years of healthy life: the healthspan–lifespan gap widened to a mean of 9.6 years (Garmany & Terzic, JAMA Network Open, 2024).

How researchers try to capture it

There is no single agreed-upon healthspan metric, which is what makes the concept easy to oversell. Researchers approach it several ways:

Health-adjusted life expectancy (HALE): the WHO summary measure used in the study above, which subtracts years lived with disease or disability from total life expectancy.
Functional measures: gait speed, grip strength, and the ability to perform daily activities, which track how well someone is aging and predict survival.
Composite indices combining biomarkers and function: informative but not standardized across research groups.

Functional measures are striking precisely because they are simple. A 2011 pooled analysis of 9 cohorts (34,485 adults aged 65+) in JAMA found gait speed strongly predicted survival, with a pooled hazard ratio of 0.88 per 0.1 m/s faster walking (95% CI, 0.87–0.90). A 2015 Lancet report from the PURE study (139,691 participants, 17 countries) found grip strength an even stronger predictor of mortality than systolic blood pressure: each 5 kg reduction raised all-cause mortality risk by 16% (HR 1.16; 95% CI, 1.13–1.20).

Measure	Source	Finding
Healthspan–lifespan gap	Garmany & Terzic, JAMA Network Open 2024	Global mean 9.6 yr; US 12.4 yr
Gait speed	Studenski et al., JAMA 2011	HR 0.88 per 0.1 m/s for survival
Grip strength	Leong et al., Lancet 2015	HR 1.16 per 5 kg drop in mortality

Rollator, senior, old human — illustrating Measuring Healthspan vs Lifespan

The measurement problem, plainly

Because there is no consensus definition, “healthspan” claims deserve scrutiny. When a product or protocol promises to extend it, ask: by what measure, in whom, over how long? Often the honest answer is that the supporting data is thin, short-term, or based on surrogate markers rather than how people actually function over years.

The takeaway

Healthspan (years lived in good health) is probably the metric that matters most, and the global gap is real and growing. But it lacks a single standard definition and is easy to market around. The practical move is to focus on inputs with strong evidence behind them (fitness, strength, and metabolic health) and to treat functional markers like walking speed and grip strength, which genuinely predict survival, as more trustworthy than any single “longevity score.”