Scotland's most treasured institution, the NHS, is under unsustainable pressure.

An urgent review is required to ensure that the right staff and resources are in place to care for patients now and in the future as demand for health and social care services grows.

The Herald has been highlighting this issue for 18 months now in our NHS: Time for Action campaign, backed by doctors, nurses and other healthcare professionals, but now Audit Scotland, the public sector's independent auditor, has added its authoritative voice to calls for action.

In a hard-hitting report, it emphasises the huge pressures on the NHS right now and how that is making it significantly harder to deliver a much-needed plan to move more services into the community by 2020 in order to help people avoid admission to hospital.

It paints a picture of an NHS caught in a perfect storm caused by growing demand from an ageing population and increasing numbers of people with long-term and complex conditions; tightening finances, with budgets to fund day-to-day care up by just more than one per cent in real terms in 2013/14 and smaller real-terms increases planned from 2014/15 (spending per person has decreased); serious cost pressures; and challenging performance targets, some of which are already being missed - and all this at a time when it is expected to undergo its greatest transformation in a generation.

Ministers seem unwilling to admit to the scale of the problem now looming ahead of them, but that position has become increasingly untenable. What this report underlines is that there is not enough money in the system now, and not enough projected to be spent on the NHS in future, to allow it to cope with everything it is expected to achieve.

What is needed to start with, as Audit Scotland identifies, is a review of projected future demand to identify what resources are required and where; detailed plans for moving to new models of care; greater understanding of how blockages occur in the system; and a review of current financial and performance targets to see if they can be achieved at the same time as implementing plans for integrated health and social care. Ministers must acknowledge that tough choices may have to be made.

The underlying issue is one of money. The NHS needs its funding increased and sustained at a higher level; how to achieve this is the debate that politicians of all shades must now be prepared to have with voters.

Unfortunately ministers have so far sidestepped the issue. In its response today, the Scottish Government highlights an increase in the NHS revenue budget without acknowledging it has not risen by enough. Can new community-based services not simply be funded by savings made from cutting back hospital services? Not initially: demand for hospital-based care will not reduce until more patients are diverted into community-based services, so new money must be found to get those in place first.

Meanwhile, blaming Westminster for budgetary constraints sounds increasingly hollow, since there is nothing to stop the Scottish Government from raising tax to improve NHS spending. Its tax-raising powers will be enhanced first next year under the Scotland Act and then again under plans for greater devolution. The incoming First Minister Nicola Sturgeon has said the NHS will be her "daily priority": if that is so, then she must be prepared to consider using these powers to better fund it.