Life Expectancy: What do we know?

 

The following table shows the life expectancy for the three years 2007-9, for the six boroughs in South East London, London, and England, with their associated 95% confidence intervals.

The following charts depict the same data visually.

The variation in life expectancy for males across South East London boroughs is about four years, while for females it is about three years. Lewisham’s relative position near the lower end is similar in both males and females.

The following table show the changes in life expectancy from 2000 to 2009, for Lewisham and England, with their associated 95% confidence intervals, together with the gap (in years) between Lewisham and England, and the gap as a percentage of the England value in the same year (“relative gap”).

For males the relative gap between Lewisham and England has fluctuated from year to year, but at 2007-09 it was as wide as at the start of the period. For females there has been a steady reduction, implying that life expectancy of females in Lewisham is increasing more rapidly than in England as a whole.

The following table shows life expectancy by Ward in Lewisham with 95% confidence intervals, together with Borough, England, and London comparators for the 5-year period 2004-2008.

The following charts depict the same data visually.

The following charts show the same data, with wards ordered by life expectancy.

For males, Forest Hill, Sydenham, Bellingham, Perry Vale, Evelyn, Ladywell, Brockley, Rushey Green, Downham, New Cross, and Lewisham Central wards all have life expectancy significantly lower than England and London. New Cross and Lewisham Central have life expectancy significantly lower than the Lewisham overall. Crofton Park and Blackheath wards have significantly higher life expectancy than Lewisham overall. No ward had significantly higher life expectancy than England and London.

For females, Sydenham, Forest Hill, Ladywell, Rushey Green, Bellingham, Telegraph Hill, New Cross and Lewisham Central wards all have life expectancy significantly lower than England and London. Telegraph Hill, New Cross and Lewisham Central have life expectancy significantly lower than Lewisham overall. Crofton Park has significantly higher life expectancy than England, London, and Lewisham overall.

The Slope Index of Inequality (SII)
From 2009/2010 a new indicator for health inequalities within a local authority was introduced, the “Slope Index” of inequality. This is a single score which represents the gap in years of life expectancy between the least deprived and most deprived within a borough, based on a statistical analysis of the relationship between life expectancy and deprivation scores across the whole of Lewisham. The SII is most easily understood with reference to a graph. The graph from which 2003-2007 SII for males in Lewisham was devised is shown below1. Lewisham’s population was divided into deciles, by grouping LSOAs according to their IMD score. Life expectancy at birth was calculated for each of the deciles and plotted on the graph in blue, with 95% confidence limits. Hence the blue dot towards the left of the graph shows that for males in the most deprived 10% of LSOAs in Lewisham, life expectancy was 70.7 years (95% confidence interval 69.5 to 71.8 years). In contrast, the equivalent figures for the least deprived 10% of LSOAs for males in the Lewisham were 79.2 years (78.0 to 80.4 years). Following further statistical adjustment, in which a linear regression was performed to get the best-fit straight line for the data, the result can be interpreted as a difference in life expectancy of 7.6 years (5.1 to 10.1) between the most and least deprived males within Lewisham.

Using the SII as an indicator of health inequalities within Lewisham, with the goal of reducing health inequalities, a decrease in the SII will represent progress. This applies only within Lewisham, and gives no indication of progress relative to the rest of the country.

The following table shows the most recent (for 2005-2009) SIIs for boroughs in South East London, with 95% confidence intervals.

The following chart shows the same data, graphically.

For males, Lewisham has the second lowest SII in South East London. For females Lewisham has the lowest SII in South London. For females in this period the confidence interval includes zero, which means that it would be consistent with the data for there to be no gradient of life expectancy by deprivation. However, it would be a mistake to place too much reliance on this, as because of the degree of uncertainty as measured by the width of the confidence intervals, no borough in South East London is statistically significantly different from any other for either sex. In term of comparison with London, Lewisham ranks 10th lowest for males, and 6th lowest for females.

The following table shows Lewisham’s SSIs from 2001-5 (the first year for which data is available) to 2005-9.

The following chart shows the same data graphically, together with the median value for England (the value for which there are as many local authorities with higher values as with lower values).

For males the SIIs have fluctuated over the period. For females there seems to have been a steady downward trend, but, as the SII has reduced, the 95% confidence intervals have widened. No year was significantly different from any other for either males or females.

Sources for Life Expectancy data
Life expectancy at Borough level came from the Compendium of Public Health Indicators. Life expectancy at Ward level came from the London Health Observatory, and is available from the London Health Programme website. A detailed explanation of the Slope index of Inequality, together with the data itself, can be found at the Association of Public Health Observatories website.

References

  1. Association of Public Health Observatories, 5LFLewishamPCTSlopeIndex-LEdeciles[1].pdf Data in deciles for the PCT was given for 2003-7 only.
  2. NHS IC Indicator Portal
  3. Health Needs Assessment Toolkit
  4. Association of Public Health Observatories (APHO)

 

 

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