Eisai has challenged the UK’s National Institute for Health and Clinical Excellence (NICE) for failing to make critical data available in its ongoing review of how widely drugs to treat dementia should be prescribed under the National Health Service.

Despite recommending anti-dementia drugs for both mild and moderate AD in 2001, the NICE proposed in May that only patients with moderate disease be allowed to receive the medicines on the NHS, according to the drugmaker. This would effectively bar an estimated 72,000 patients in the UK from access to them.

The news came just as formal appeals against the ruling, which started on Thursday and continue today, got underway.

Eisai, which makes the Alzheimer's disease treatment Aricept (donepezil), has referred the case to the Parliamentary Ombudsman, saying it has repeatedly asked for details of the mathematical model which NICE used to assess various assumptions about price and effectiveness of treatment. Other drugs affected by the NICE ruling include Shire's Reminyl (galantamine) and Novartis' Exelon (rivastigmine).

After the NICE persistent refusal to make these available, Eisai complained to the Information Commissioner, asking him to intervene. However, the firm says that his failure to act has promoted its decision to report the matter to the Parliamentary Ombudsman.

The health economist Dr Richard Phillips said: “It is not possible to effectively question the cost-effectiveness evaluations undertaken by NICE during this assessment without access to a working version of the model.”

One point of contention is that the use of quality-adjusted life years (QALYs) to measure the worth of dementia treatments is unfair, because they can discriminate against older patients as greater QALY benefits can be gained by treating younger people with longer life expectancies.

NICE has insisted that it decided not to disclose the model because this would constitute a breach of confidence with a third party which drew up the model. The calculations were initially performed on behalf of NICE by the University of Southampton Technology Appraisal Centre (SHTAC)