Estimated and projected diagnosis rates for dementia in Scotland 2014-2020

1. Introduction

This report was commissioned from NHS National Services Scotland's Information Services Division ( NSS ISD) by The Scottish Government,

The purpose of the commission was to establish, for the first time, an estimated annual dementia diagnosed incidence rate for Scotland; which would in turn help contextualise post-diagnostic performance data against The Scottish Government's national LDP Standard for post-diagnostic support. Incidence refers to the estimated number of new dementia cases developed in a given time period. Prevalence refers to the estimated snapshot of the number of cases in a population at a given point in time. This report is concerned with estimated diagnosed incidence

Improving post-diagnostic support has been a key part of The Scottish Government's National Dementia Strategies since they were first developed. Commitment 2 of Scotland's National Dementia Strategy (2013-16) states that "We will transform the availability, consistency and the quality of post-diagnostic support by delivering the new post-diagnostic HEAT target".

The LDP Standard (originally HEAT Target) sets out the commitment ' To deliver expected rates of dementia diagnosis and by 2015/16, all people newly diagnosed with dementia will have a minimum of a year's worth of post-diagnostic support coordinated by a link worker, including the building of a person-centred support plan' and came into effect from April 2013. Reported achievements towards this LDP Standard for each NHS Board are due to be published soon, highlighting performance in respect of those individuals who entered the post-diagnostic service ( PDS) between 1 April 2014 and 31 March 2015.

1.1 Purpose of Report and History of Estimating Individuals Diagnosed with Dementia

To allow for the calculation of the LDP Standard and to set performance in a meaningful context, there was a need to acquire an estimate of the number of individuals newly diagnosed with dementia in a given year within each NHS Board.

An initial attempt at deriving this estimate was obtained from analysis taken from a Medical Research Council - funded study, "The Incidence of Dementia in England and Wales: Findings from Five Identical Sites of the MRC CFA Study" (Matthews & Brayne, 2005 ^[1] ). Limitations of the study were of the assumption of a patient's survival time post-diagnosis and the number of individuals dying after developing dementia before receiving a formal diagnosis.

This initial estimate was then used to estimate numbers of people with dementia in order to inform each NHS Board about the resources required for their local PDS services. However, the early Dementia PDS data returns from the Health Boards to ISD suggested that the number of individuals qualifying for and using the PDS service was higher than anticipated. This indicated that the initial analysis was a substantial underestimation

In response, The Scottish Government requested that ISD carry out an investigation into the initial calculations of the estimates. It was discovered that there had been a misinterpretation of the results from the MRC study (Matthews et al., 2005) which the analysis had been based on. This then resulted in an under-estimation of the rate of diagnosis of dementia in a given year in Scotland. It is thought that the initial dementia diagnosis rate is likely to have been under estimated by approximately 50%.

1.2 Consideration of New Methodologies

After stakeholder consultation it was decided to undertake a new approach to determining estimated diagnosis rates of dementia in Scotland. This led to the commissioning of the new 'Estimated and projected diagnosis rates for dementia in Scotland; 2014-2020' project.