Signature
RII_mean = SII / mu
| Inputs | Definition | Unit |
|---|---|---|
SII | Slope index of inequality from HE-FM-HINQ-002 | health units, for example years of QALE |
mu | Population-weighted mean health across all groups. Above zero | health units, in the same unit as SII |
RII_mean | Relative index of inequality as the slope index divided by mean health | proportion of mean health, without unit |
|---|
Function
Health inequality measures across ordered population groups
Maps the mean health of population groups, ordered from the most to the least disadvantaged, and the share of the population in each group to summary measures of socioeconomic-related health inequality: the absolute and relative gaps between the extreme groups, the slope index of inequality, the relative index of inequality in two forms and the concentration index. The measures describe how health varies with socioeconomic position and do not say whether that variation is unfair, which is the separate judgement of health inequity. The Atkinson index, which ignores the ranking of groups, has its own records on the Atkinson index page (HE-FN-ATK-001) and is not repeated here.
Try this function
Implementations
Excel
Mean-scaled relative index of inequality in one Excel cell
With the slope index in a cell named SII and population-weighted mean health in a cell named MeanHealth, Excel returns the mean-scaled relative index.
=SII/MeanHealth
Assumptions
Ratio-scale health for the mean-scaled relative index
Health is on a ratio scale with mean above zero. This form is unchanged when every health value is multiplied by the same factor and falls when the same amount is added to everyone, as in Programmes B and A of the article.
Worked examples
Mean-scaled relative index for five equal deprivation quintiles
In the article's example the slope index of 12.5 years divided by mean QALE of 68 years gives 12.5 / 68 = 0.1838, which the article rounds to 0.184.
SII = 12.5; mu = 68; RII_mean = 0.1838
Mean-scaled relative index for no screening in the DCEA tutorial
For the no-screening strategy in the tutorial by Asaria and colleagues, a slope index of 12.88747 years and mean QALE of 69.260 years give 0.18607, the relative index of inequality reported in their Table 8.
SII = 12.88747; mu = 69.260; RII_mean = 0.18607
Common errors
Comparing relative index of inequality values of different forms
The same quintile data give 1.2024 in the ratio form and 0.1838 in the mean-scaled form. Placing a value of one form beside a value of the other, or reading the ratio form minus 1 as the mean-scaled form, misstates relative inequality; values are converted to one form with the relation in the validation test first.
Sources
Relative index and slope index values in the DCEA tutorial
Asaria M, Griffin S, Cookson R. Distributional cost-effectiveness analysis: a tutorial. Medical Decision Making. 2016;36(1):8-19. Table 8, which reports the relative index of inequality and the slope index of inequality for four bowel cancer screening strategies; each relative index equals the slope index divided by the overall average QALE in the table of QALE by subgroup, for no screening 12.88747 / 69.260 = 0.18607.
Canonical Identity
Stable URI · Machine-readable · Resolvable · CC BY 4.0