Fifteen per cent of patients faced waits of more than a year to receive elective treatment at one hospital trust, Department of Health figures reveal.

Kingston Hospital Trust skewed the results for the rest of the sector, largely accounting for a 61 per cent increase nationally in the number of people waiting more than six months for treatment.

DH referral to treatment time statistics released today show that of the 15,488 people with “incomplete pathways” for elective care at Kingston Hospital in June, 2,314 had waited more than 52 weeks.

The number of six-month plus waiters at Kinsgton leapt from 543 in June 2010 to 4,723 in June 2011.

Chief operating officer Sarah Tedford said: “Earlier on in the year, we discovered that there was a problem with the processes we use to administer our waiting lists. Over the last few months we have carried out a major overhaul of these processes and have now completely changed the way we manage these systems.”

The target for acute trusts is for 90 per cent of elective patients to wait no longer than 18 weeks from referral to treatment time, but this can see trusts hit this target whilst leaving some people to wait much longer.

The Department of Health said nationally 90.2 per cent of admitted patients took no more than 18 weeks from referral to treatment in June, just above the 90 per cent target.

This figure from the first quarter of 2011-12 shows a deterioration of 2.9 percentage points from the same period in 2010-11.

Kingston Hospital saw 70 per cent of patients within 18 weeks of referral in June, one of 47 trusts to miss the target.

The south-west London trust’s proportion of patients waiting more than a year is far worse than anywhere else in England - only two other hospital trusts had more than two per cent of patients waiting more than a year.

Wirral University Teaching Hospitals Foundation Trust’s list has seen 3.5 per cent of patients wait a year or more.

The figure for Sheffield Teaching Hospitals Foundation Trust was 2.3 per cent.

The same measure for March 2011 showed 10 per cent of Kingston Hospital’s patients with “incomplete pathways” had waited more than a year.

Wirral’s figure was three per cent and University College London Hospitals Foundation Trust five per cent in the same month.

In December 2010 only 18 out of the 13,000 patients with “incomplete pathways” had been waiting more than a year.

St George’s Healthcare Trust in south London did not submit the information for June and has faced serious data quality problems since switching to the Cerner Millenium system in March.

Its chief executive last month reported it is “facing issues with a large volume of data with no pathway ID and the quality of data”.

The trust is also still investigating a “significant clinical risk” after a backlog of medical letters built up because the company doing the hospital’s transcription went into administration.

Responding to the figures NHS Confederation chief executive Mike Farrar said:  “The NHS has made huge progress on waiting times in recent years and nobody wants to see those hard-won gains lost.

“This data is further evidence that patient access will be stretched as the financial situation gets increasingly pressured.”