Few people in the UK with early stage Alzheimer’s disease are likely to be suitable for the latest drugs which aim to halt progress of the condition, a new study has found.
The research is published in the Journal of Neurology Neurosurgery & Psychiatry.
Disease-modifying drugs, lecanemab and donanemab, slow cognitive decline in people with early stage Alzheimer’s disease.
The medicines have been granted ‘breakthrough therapy’ status in the UK because of their ability to remove beta amyloid protein in the brain, the build-up of which is thought to have a key role in the development of the disease.
Licensed for the treatment of Alzheimer’s disease in the US in 2023, regulatory approval of these drugs for use in the UK is expected shortly.
But to maximise their effectiveness, a raft of clinical staff and diagnostic and monitoring tests and scans will be required, researchers have said.
They wrote: “While a sizeable proportion of patients attending memory clinics may be referred for triaging for [disease modifying drugs for Alzheimer’s disease], only a minority are likely to be suitable for these, as demonstrated in patients seen in specialist cognitive services.
“This will need to be considered when designing pathways for delivery [of these drugs].”
To gauge the potential level of healthcare demand, the researchers retrospectively evaluated patients attending five community memory services across North and East London and a national specialist cognitive disorders service between January and June in 2022.
They wanted to find out the proportion of patients who would likely be referred for triaging from the memory services for these new drugs as well as those from the specialist service who would potentially be suitable for treatment with them.
In all, the anonymised case files of 1017 patients were included, 517 of whom were seen in community memory services and 500 in specialist clinics.
Just over 40 per cent of the memory service patients were men; their average age was 79, with just 14 per cent (72) under the age of 70.
After exclusions due to incomplete data and factors, such as symptom severity, frailty, and other coexisting conditions, nearly one in three (163; 31.5 per cent) were potentially eligible for treatment with the new drugs.
Of these, 161 had undergone neuroimaging; but fluid biomarker tests were carried out in only two patients.
This is equivalent to less than one per cent of the memory clinic patients included in the study, “making this an urgent area of need for service development to enable identification of suitable patients,” the researchers said.
Based on these figures, they suggest: “With an average memory clinic caseload of 815 and 80 nationally accredited memory clinics in England and Northern Ireland, potentially over 20,000 people per year will need access to such confirmatory investigations.”
More of the specialist clinic patients were men (53 per cent) and they tended to be younger.
Their average age was 66, but well over half (58 per cent) were under the age of 70. Alzheimer’s disease was the most common diagnosis (35.5 per cent), followed by frontotemporal dementia (72;14.5 per cent).
Most of them (492) had been given diagnostic scans: computed tomography or magnetic resonance imaging.
And fluid biomarker tests were performed in nearly two thirds (62 per cent) of those with Alzheimer’s disease.
But after exclusions due to frailty and contraindications for treatment, etc, only 40 per cent of the Alzheimer’s disease patients were potentially eligible for treatment with the new drugs, equivalent to just 14 per cent of all the cases reviewed at the specialist cognitive clinics.
The researchers said: “Systems need to be set up to deal with this potential large mismatch between referral and ultimate eligibility in order to avoid overwhelming services.
They added: “A significant issue is that due to the lack of biomarker testing in community memory clinics, the clinical suspicion of [Alzheimer’s disease] is likely to be incorrect in at least 30 per cent of cases.”
