Is it time to replace the Abbreviated Mental Test Score as a screening tool for dementia?

Michelle Willmott

doi:10.7861/clinmedicine.15-3-s9

Aims

To compare the case-finding ability of the Abbreviated Mental Test Score (AMTS) to the mini-COG in elderly hospitalised patients, with the ultimate aim of improving screening for dementia.

Methods

The AMTS and mini-COG were administered to a cohort of 40 inpatients aged 68–94 (median age 82, mean age 81.1) over a 2-week period. Three doctors administered the tests and one doctor performed all of the scoring.

Results

Of the 40 patients screened, eight were identified as ‘cases’ by the AMTS. The mini-COG identified the same eight patients, but went on to detect a further 11 ‘cases’.

All 11 of these additional ‘cases’ had abnormal clock-draws. The following are examples of clock-draws from two of these 11 patients who had a normal AMTS but an abnormal mini-COG. It is immediately obvious that there is significant visual–spatial impairment in both of these patients, and that further diagnostic assessment should be performed.

Conclusions

Dementia is a prevalent, costly but under-diagnosed condition that has been made a focus of this government's healthcare policy and current research drives, culminating most recently with the discovery of diagnostic serum markers in July 2014. The prime minister's ‘Dementia Challenge’, launched in 2012, aimed to raise the diagnostic rate above its current 45% and financially incentivised hospital trusts to do this through the Dementia Commissioning for Quality and Innovation (CQUIN) scheme, which allows trusts to earn up to £54m a year for reaching specific targets. Sixty per cent of the budget alone is allocated to trusts that attain a 90% case-finding target.

In order to achieve this, hospitals need a rapid and valid screening tool for dementia to use in the emergency department. The AMTS (designed in 1972) may not be fit for purpose in today's multi-ethnic patient cohort. No previous studies have compared the AMTS to the mini-COG – a newer and quicker screening tool, with minimal language content that reduces its educational and cultural bias. This preliminary audit shows that the mini-COG identified more potential ‘cases’ in this patient cohort than the AMTS; these will now need to be followed up prospectively to see whether they are diagnosed with dementia.

In summary, these results suggest that the mini-COG is a better screening tool for dementia than the AMTS in this patient cohort, and could therefore supersede its use. Further follow-up is needed to provide more evidence to support this.