Responses to the review of co-payments have revealed the extent of uncertainty about the way forward for the NHS on top-ups.
Organisations that allowed HSJ to see their submissions to the consultation raised fears including: top-ups resulting in added costs for the NHS; unintended consequences such as the creation of a co-insurance market; the need to create strict rules about when top-ups would be allowed; and the need to explain to patients why the NHS had decided not to allow additional payments if it took this course of action.
In its response, the NHS Confederation said reluctantly that the current position on top-ups was "almost certainly unsustainable".
In a letter to national cancer director Mike Richards, who is carrying out the review, confederation policy director Nigel Edwards said: "Members found the issue very difficult. The view of most of the members we consulted was that they would rather there were no top-ups at all allowed in the NHS."
Think tank the King's Fund, which is yet to decide whether it is for or against additional payments, warned if rules were relaxed, pressure would mount to make cost-ineffective drugs available and could undermine the National Institute for Health and Clinical Excellence.
Trade union Unison warned that over time a system of co-payments could reduce the NHS to providing basic services only, with more elaborate or expensive treatments requiring top-ups.
It said: "The reputation of the NHS as a system of social insurance, funded by taxation, based on need and not ability to pay, would be seriously undermined by the wholesale introduction of co-payments and the increased inequalities that this would engender."
It called for the debate to be "re-framed beyond the current media furore".
"Any discussion about what is essentially healthcare rationing will always be hugely emotive, but taking any major decisions that could affect the universalist aspirations of the NHS on the basis of this four-month review should be out of the question," it said.
The news came as NICE revealed it is undertaking a routine review of its methods for valuing new treatments. The findings of the research, conducted by the King's Fund, City University and Brunel University, will be revealed in a workshop next year which will explore "a range of issues around cost-effectiveness".