The past financial year saw a sharp rise in the proportion of primary care trusts reporting above-average costs for providing NHS services, new Department of Health figures show.

Last Friday the department published its reference cost index for 2010-11, a measure of the relative efficiency of organisations across the NHS.

It showed that the proportion of PCTs reporting above-average costs had risen to 58 per cent, up from 49 per cent the previous year.

Meanwhile, the proportion of provider organisations reporting above-average costs fell slightly, to 39 per cent, down from 41 per cent in 2009-10.

The index measures organisations’ costs as a percentage of the average cost of delivering services. A reference cost index score of 110 means the organisation pays 10 per cent above average costs to deliver services, while a score of 90 means its costs are 10 per cent below average.

Among the 114 primary care trusts that provided data, NHS Sutton and Merton saw the steepest rise in reference costs, from 83 in 2009-10 to 114 last year. Walsall Teaching PCT reported the highest overall costs, at 26 per cent above average. NHS Great Yarmouth and Waveney reported the lowest reference costs, at just 69 per cent of the national average.

When it came to providers, Cornwall Partnership Foundation Trust reported the highest costs in England, at 34 per cent above the national average. Hertfordshire Partnership Foundation Trust reported the lowest reference costs in the country, at 82 per cent of the national average.

Audit Commission managing director of health Andy McKeon said the figures showed much less variation in the costs of acute providers than it did for community services and mental health trusts. This might mean the way the data was collected was not accurately capturing the costs of the latter organisations, he suggested.

“[The collection] is a fair reflection of [the costs of] most acute trusts, but it may not be accurately measuring what community, mental health, and possibly some specialist providers do,” he said.

The 2010-11 collection covered £53bn of NHS expenditure, an increase of 3 per cent on the previous year, with costs provided from 392 providers. It will be used to inform the setting of 2013-14 tariff prices.