Dear Ed,
I am writing to you to request the suspension of accreditation of National Records of Scotland’s (NRS) Healthy Life Expectancy estimates for Scotland, starting with the upcoming ‘Healthy Life Expectancy, 2021-2023’ publication, which is currently badged as Accredited Official Statistics.
Our healthy life expectancy methodology was based on data from the Annual Population Survey (APS), consistent with the Office for National Statistics’ (ONS) approach. Due to issues around decreasing APS sample sizes as established by ONS’ review, it is no longer possible to produce reliable Healthy Life Expectancy estimates under the existing methodology.
Therefore, from our ‘Healthy Life Expectancy, 2021-2023’ publication onwards, we are adopting ONS’ new interim Healthy Life Expectancy methodology, which was first used in ONS’ ‘Healthy life expectancy in England and Wales: between 2011 to 2013 and 2021 to 2023’ publication. This new interim methodology still uses APS data as an input, but uses logistic regression modelling to seek to mitigate the impacts of decreased APS sample size on the reliability of the estimates.
ONS are producing the estimates for our ‘Healthy Life Expectancy, 2021-2023’ on our behalf using this interim methodology. To align with ONS, we will continue to use the interim method in subsequent publications until their review of health data sources to support a final methodology has been completed.
As I mentioned above, ONS have reviewed the quality of their APS-based outputs, which includes their Healthy Life Expectancy publication, and in December 2024 wrote to you to request suspension of accreditation due to quality concerns centring around estimates for sub-national geographies, such as Local Authorities.
Considering the small population of several of our Health Boards and Local Authorities, we consider these quality concerns especially relevant for estimates for Scotland. Estimates of healthy life expectancy at Health Board level may be used to inform healthcare provision, and we have some Health Boards with especially small populations that will be particularly affected.
ONS have designated their latest release, which uses the interim method, as Official Statistics in Development. As we will be publishing figures produced by ONS using the same method, and ONS has requested suspension of accreditation for their own publication following their quality review, we are requesting the suspension of accreditation for our upcoming ‘Healthy Life Expectancy, 2021-2023’ publication on the 29th July 2025, and all subsequent Healthy Life Expectancy publications. This suspension of accreditation will make the limitations of the analysis clear to users, and support the appropriate use of the results. It will also ensure methodological coherence between our estimates for Scotland and ONS’ estimates for the UK.
If you are in agreement with suspending accreditation, we intend to publish ‘Healthy Life Expectancy, 2021-2023’ as Official Statistics in Development on the 29th July 2025, while work to improve the quality of the estimates via the development of the final methodology is in progress.
Yours sincerely,
Alan Ferrier