Patients with a rare but life-threatening disease have protested at Parliament over what they say is the failure of the health system to address their needs.

It is estimated five or six New Zealanders have Pompe Disease, an inherited disorder caused by an enzyme deficiency.

Four patients attended the rally, on Wednesday, with supporters.

Spokesperson John Forman says the Drug Buying Agency Pharmac has turned down applications to pay for a treatment that would help, a medicine known as myozome.

"The system has failed our patients. Their applications have recently been rejected on cost grounds alone and issues of equity, community value and fairness were explicitly excluded from the decision-making process by Pharmac."

High-cost medicines likely to benefit just a few patients are known as orphan drugs, and the patients say a review by Pharmac of the scheme by which people gain access to such medicines has failed them.

Pharmac says the treatment would cost between $650,000 and $1.3 million a year for a patient, indefinitely.

It says the applications were declined because of a lack of evidence demonstrating benefits to justify the cost.

However, Pharmac says it is introducing an improved scheme next year to improve access to the medicines and the patients can re-apply.

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