Some London hospital trusts could safely cut their spending on nurses by half, NHS London documents have claimed.

The strategic health authority published its Sustainable and Financially Effective report in February, which showed the potential for £421m in savings from the £1.5bn annual nursing bill – around a third.

But individual reports at trust level last week, obtained by HSJ under the Freedom of Information Act, show some trusts are able to save an even greater proportion of their nursing budget.

The documents say that if the highest possible level of efficiencies was achieved Newham Hospital Trust could save half of its £42m nursing bill, while the Whittington Hospital Trust could see its nursing bill fall from £49m to £25m.

Sustainable and Financially Effective was commissioned last year to assess the viability of London’s non-foundation trust hospitals.

The analysis was carried out by the strategic health authority using some methodology from consultants McKinsey. It concluded that the capital’s hospital sector was “not sustainable in [its] present form”.

“Ways of working may be more important than resourcing levels and whilst some individual clinical areas will undoubtedly require more resource, efficiency improvements will enable others to deliver improved quality with fewer staff,” the report said.

It also recommended “incentivising” nurses to work in “deprived areas and/or failing trusts” and establishing a staff bank across a network of trusts.

However, the methodology and conclusions were criticised by academics.

Jill Maben, director of the national nursing research unit at King’s College London, said the measures used in the reports appeared unsophisticated. She pointed out that the figures did not reflect the acuity of patients.

Professor Maben added that the total currently spent on nurses could represent good value for money if it reflected specialists doing work that would otherwise be done by a junior doctor.

Keith Hurst, editor of the International Journal of Health Care Quality Assurance, said: “Generally, I found the analysis flawed and outcomes troubling.”

He said the methodology appeared to take no account of differences between pure acute trusts and those that also provided community and learning disability services, where length of stay was much longer.

A spokesperson for NHS London said: “In the Sustainable and Financially Effective report three different sets of figures are used to calculate potential savings for each trust and all represent theoretical productivity opportunities, not a plan to implement changes.