How is the HALE calculated ?

WHO uses life tables and Sullivan's method to compute the HALE for countries. The calculation method also includes a weight assigned to each type of disability to adjusted for the severity of the disability.

Mortality data for calculation of life tables are obtained from death registration data reported annually to the WHO. For countries without such data, available survey and census sources containing information on child and adult mortality are analysed and used to estimate life tables.

Estimations of prevalence data are obtained from the WHO Global Burden of Disease (GBD) study, the WHO Multi-Country Survey Study (MCSS) and the World Health Survey (WHS).

A four-stage strategy is used to overcome the problem that comparable health state prevalence data are not available for all countries:

1) Data from the WHO GBD study are used to estimate severity-adjusted prevalence by age and sex for all countries.

2) Data from the WHO MCSS and WHS are used to make independent estimates of severity adjusted prevalence by age and sex for survey countries.

3) Prevalence for all countries is calculated based on GBD, MCSS and WHS estimates.

4) Life tables constructed by the WHO are used together with Sullivan's method to compute the HALE for countries.

Lack of comparable and reliable data on mortality and disease prevalence

A major challenge with the HALE indicator is the lack of reliable data on mortality and morbidity, especially from low income countries. Other problems with the indicator include the lack of comparability of self-reported data from health interviews.

Source:

WHOSIS (WHO Statistical Information System) Indicator Definitions and Metadata

Also see:

Methods for Measuring Healthy Life Expectancy