Local inequality indicators

We constructed clinical commissioning group level indicators using similar methods as we used to construct the national inequality indicators. Our absolute inequality indicator at CCG level is based on running local level regressions using just those LSOAs that fall within a CCG, and modelling the “social gradient” relationship between the outcomes of these LSOAs and their national deprivation ranks. The deprivation rank we used was the national

deprivation rank rather than recomputed local within-CCG deprivation rank. We did this in order to allow us to compare the within-CCG inequality gradient with the national inequality gradient in a straightforward manner. We labelled this indicator the “absolute gradient index” (AGI) to distinguish it from variants of the SII at local level that use the local deprivation rank. We also calculated a relative version of this indicator at CCG level, analogous to the national RII, that we called the relative gradient index (RGI). To maintain comparability with the national RII, this was computed as the AGI divided by the national mean level of the indicator. Dividing by the local mean would potentially bias comparisons against the

national RII benchmark by decreasing measured local relative inequality in areas with higher- than-average mean levels of the indicator outcome (e.g. relatively deprived CCGs with above-average levels of preventable hospitalisation), and vice versa. National and local level results were graphically combined to compare the CCG with the national level results as shown in the figure below.

This approach differs from the Public Health Outcomes Framework (PHOF) approach54 to calculating within-CCG SIIs. The PHOF approach uses local deprivation ranks recalculated within CCGs, and then deprivation decile level regressions based on these local ranks. This

difference is due to the difference in purpose between healthcare equity indicators and public health equity indicators. The main difference is that our healthcare equity indicators aim to compare local healthcare inequalities against a national benchmark, whereas the public health equity indicators focus on comparing the same local area over time. For our purpose of making comparisons against a national benchmark, using a common deprivation scale

between the national and CCG level indicators is appropriate. A second difference is that our indicators focus on role of the NHS in reducing the link between deprivation and ill-health, rather than in reducing deprivation and income inequality per se. By contrast, the PHOF indicator seeks to pick up the success of local government both in reducing the deprivation- health link and also in reducing deprivation and income inequality per se. Our more specific focus is reasonable insofar as changes in local prosperity are largely caused by factors outside NHS control – though of course NHS actions can have consequences for people’s wealth by protecting them against catastrophic healthcare costs and keeping them economically

productive. To measure the deprivation-health link specifically, we need to use the absolute national deprivation rank rather than the relative within-CCG deprivation rank. In principle, our measure will then not be sensitive to “gradient preserving” changes in local economic prosperity if this leads to precisely corresponding changes in health and healthcare along the national social gradient.

Figure 6 Absolute inequality graph for a hypothetical CCG showing the AGI slope, inequality gap, within CCG LSOA level results, national and CCG average for an example indicator (e.g. preventable hospitalisation per 1,000 general population)

We also plotted the full range of CCG level inequality results against the national inequality result on a caterpillar plot, showing data for the most recent year to help us identify areas that performed significantly better or worse than the national average in terms of inequality. An example of such a plot is shown below.

Figure 7 CCG level caterpillar plot comparing absolute inequality at CCG level in terms of AGI to absolute inequality at national level in terms of SII

As a final analytical tool we produced plots of CCG level average achievement and inequality achievement by deprivation to get some understanding of the contributions between CCG and within CCG inequality to the national inequality results. An example of such a plot is shown in the figure below.

Figure 8 Correlations between deprivation and average and inequality performance at CCG level

As with the national inequality indicators, we tested a range of alternative regression models to ensure the robustness of our results. We also tested using a random effects specification of our model with CCG level random slopes and intercepts. We found that for those indicators where we had small event counts at CCG level (in particular, amenable mortality and all- cause mortality) the random effects specification had trouble converging. However, for the indicators where the random effects specification did converge we found that the magnitudes of inequality results were, as would be expected, shrunk towards the national average. However, the trends and rankings of CCGs in terms of inequality remained very similar to those observed with the standard linear model. Our base case results at local level are

therefore produced using the standard linear model as (i) this could be applied in a consistent manner across the full suite of indicators and (ii) this is a simpler approach that is easier for decision makers to understand and interpret.