Health Inequalities Gap Measurement Tool Released

A useful Health Inequalities Gap Measurement Tool (the ‘gap tool’) has been released today. This has been produced on behalf of the Public Health Observatories in England.

The gap tool is an accessible, web-based resource providing detailed information on the nature and extent of the health inequalities gap within and between all Local Authority and NHS areas in England. It uses population mortality rates to measure the inequality gap, and shows the differences in mortality rates within and between areas by grouping local populations according to relative levels of deprivation.

It can be used to support needs assessment, service planning and commissioning to reduce health inequalities by giving users the means to:

  • Identify the causes of death with the largest inequality gaps within areas;
  • See the age groups with the greatest absolute and relative gaps in mortality;
  • Compare the overall mortality profiles for different areas; and
  • View the ‘direction of travel’ for mortality rates and the local inequality gap.

The gap tool contains a range of display options which allow users to explore the local inequality gap and to make a wide range of comparisons.

It can be accessed at

We will be looking to use the tool as part of our ongoing work on the Joint Strategic Needs Assessment (JSNA) in Warwickshire.

One Response

  1. The referenced SEPHO Health Inequalities Gap Measurement Tool does not provide useful guidance for the measurement of health inequalities. The tool relies on standard measures of differences between outcome rates (proportions) without consideration of the way that, for reasons related to the shapes of normal risk distributions, those measures tend to be systematically affected by the overall prevalence of an outcome. Most notably, the rarer an outcome, the greater tends to be the relative difference in experiencing it and the smaller tends to be the relative difference in avoiding it. Thus, relative differences in mortality tend to be large among the young while relative differences in survival tend to be large among the old. Absolute differences and odds ratios also tend to be affected by the overall prevalence of an outcome, though in a more complicated way. Roughly, as uncommon outcomes become more common absolute differences tend to increase; as common outcomes become even more common, absolute differences tend to decrease. Differences measured by odds ratios tend to change in the opposite direction of the absolute differences.

    The point is not simply that different measures tend to yield contrary results. Rather, none of the measure can provide useful information about the comparative size of inequalities without consideration of the overall prevalence of the outcome.

    SEPHO has previously recognized these issues. Its Public Health Observatory Handbook of Health Inequalities Measurement. Oxford: SEPHO; 2005 (, at 171-72, specifically discussed that patterns of relative differences in experiencing favorable or adverse outcomes are inherent in the shapes of normal distributions. Having recognized the patterns, it is not useful then to provide guidance on measurement without consideration of the patterns.

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