Monitoring health inequalities: background and methodology

Background

A Ministerial Task Force on Health Inequalities led by the Minister for Public Health was established in 2007 to identify and prioritise practical actions to reduce the most significant and widening health inequalities in Scotland. The Task Force recognised the need to monitor progress in tackling health inequalities in the longer term as well as managing short and medium term progress.   

A technical advisory group was set up in early 2008 to advise the Task Force on long-term monitoring of health inequalities. The group recommended a range of indicators to be monitored over time, as reflected in this report.

The technical advisory group most recently convened in 2019 to review proposed changes to some existing indicators and discuss the inclusion of a new indicator to monitor drug-related hospital admissions. This indicator was presented in the report for the first time in 2020 and is now included annually. 

The indicators recommended by the technical advisory group are:

Headline indicators of inequalities in health outcomes

• healthy life expectancy at birth
• premature mortality from all causes aged under 75 years
• mental wellbeing of adults

Indicators of inequalities in morbidity and mortality from specific causes for specific age groups

• coronary heart disease: first ever hospital admission for heart attack (aged under 75 years)
• coronary heart disease: deaths (aged 45-74 years)
• cancer: incidence (aged under 75 years)
• cancer: deaths (aged 45-74 years)
• alcohol: first ever hospital admission (aged under 75 years)
• alcohol: deaths (aged 45-74 years)
• all-cause mortality (aged 15-44 years)
• low birthweight
• healthy birthweight
• self-assessed health of adults (aged 16+)
• limiting long-term conditions amongst adults (aged 16+)
• drugs: hospital admissions (aged under 75 years)

Recommended approaches to monitoring health inequalities

The expert group recognised that different types of measure give insight into different aspects of inequalities. The recommended approach therefore uses a combination of measures, with the aim of giving a fuller understanding of the inequalities concerned.

• Relative Index of Inequality (RII): How steep is the inequalities gradient?  This measure describes the gradient of health observed across the deprivation scale, relative to the mean health of the whole population.  In this report, the magnitude of RII is quoted. Unless explicitly explained, the RII indicates the extent to which health outcomes are better in the least deprived areas, or worse in the most deprived areas, compared to the mean.
• Absolute range: How big is the gap?  This measure describes the absolute difference between the extremes of deprivation.
• Scale: How big is the problem?  This measure describes the underlying scale of the problem, puts it into context and presents past trends at Scotland level.

Detailed descriptions of these measures can be found in the methodology section, and in Annex 2 of the latest publication. In the absence of individual level data on socio-economic circumstance, which the group identified as the ideal but acknowledged is not yet possible, an area based index based on income and employment has been used to define “deprivation”. Details about the reasons for this and the way that this index was calculated are also provided in the methodology section and in Annex 1.

The expert group also advised that these indicators and measures were recommended for long-term monitoring of health inequalities due to deprivation at Scotland level.  Monitoring of health inequalities due to other factors (such as age, gender or ethnicity for example) would require different indicators and measures.  Similarly, the group advised that these recommended indicators and measures would not necessarily be the most appropriate for long-term monitoring of health inequalities at a local level.

The report of the Ministerial Task Force, Equally Well[1] (published in June 2008), recommended that these indicators and measures should be adopted and a report published.  The first report was published in September 2008, and updates were published in September 2009 and October of every year since 2010.

Recommendations from the Technical Advisory Group, June 2012

In June 2012, there was a further meeting of the technical advisory group to review methodology and the range of published indicators.  The meeting focussed on two main areas.  The first of these was a proposal that the assumption of a linear relationship between deprivation and each indicator be tested, and possibly replaced by a non-linear model if appropriate[2]. The second issue was whether the existing range of indicators was appropriate[3].

On the issue of applying a non-linear spline model to the measurement of relative deprivation, it was agreed that no changes would be made to the methodology. While the alternative had some technical merits, it was felt to be too complex for this report; and its lack of consistency over time had drawbacks for long-term monitoring.

On the range of reported indicators, it was agreed that the low birthweight indicator should be supplemented by an additional indicator of appropriate weight for gestational age. This was included in the 2013 report for the first time.  It was also agreed that mortality rates from the most common types of cancer would be investigated separately to total cancer mortality.

Recommendations from the Technical Advisory Group, July 2015

In July 2015, the technical advisory group met to agree short and longer term developments to the Long-term Monitoring of Health Inequalities indicators and report.

Changes incorporated in the 2015 report include a new indicator of ‘below average’ mental wellbeing, which more effectively illustrates the inequalities in mental wellbeing compared to the indicator included in previous reports.  Also, the ‘first ever’ alcohol-related hospital admissions indicator has been revised to refer to first hospital admissions in the last ten years to ensure consistency over the full reporting period.  The Scale Index of Inequality (SII) was also added to published web tables to aid in the understanding of the relationship between relative and absolute inequalities.

The group considered alternative non-linear (including exponential) models to describe health inequalities and other methodological approaches, such as the application of Statistical Process Control (SPC) methods.  The meeting agreed that these should not be a priority for development in the short term.  Work to illustrate confidence limits around estimates of the Relative Index of Inequalities (RII) will be progressed for future reports, to ensure that the significance of changes over time is suitably interpreted.

The group reiterated the importance of investigating health inequalities by educational attainment and recommended pursuing data linkage opportunities to achieve this. 

New 'morbidity indicators' based on self-reported survey data on general health and long-term conditions by household income or area deprivation were included in every second report from 2017.

Recommendations from the Technical Advisory Group, 2019

Following discussions with the technical advisory group a new indicator monitoring drug-related hospital admissions was included in the report for the first time in 2020 and will be included annually going forward.