Income inequality in life expectancy and disability-free life expectancy in Denmark.

Background: Income has seldom been used to study social differences in disability-free life expectancy (DFLE). This study investigates income inequalities in life expectancy and DFLE at age 50 and 65 and estimates the contributions from the mortality and disability effects on the differences between income groups.

Methods: Life tables by income quintile were constructed using Danish register data on equivalised disposable household income and mortality. Data on activity limitations from the Danish part of the Survey of Health, Ageing and Retirement in Europe (SHARE) was linked to register data on income. For each income quintile, life table data and prevalence data of no activity limitations from SHARE were combined to estimate DFLE. Differences between income quintiles in DFLE were decomposed into contributions from mortality and disability effects.

Results: A clear social gradient was seen for life expectancy as well as DFLE. Life expectancy at age 50 differed between the highest and lowest income quintiles by 8.6 years for men and 5.5 years for women. The difference in DFLE was 12.8 and 11.0 years for men and women, respectively. The mortality effect from the decomposition contributed equally for men and slightly more for women to the difference in expected lifetime without than with activity limitations. The disability effect contributed by 8.5 years for men and 8.0 years for women.

Conclusion: The income inequality gradient was steeper for DFLE than life expectancy. Since income inequality increases, DFLE by income is an important indicator for monitoring social inequality in the growing share of elderly people.