'Early achiever' trusts still cannot say if they hit the 18-week target by the end of 2007, because of delays in upgrading their computer systems.

Thirteen sites tried to hit the target of treating 90 per cent of admitted and 95 per cent of non-admitted patients within 18 weeks of referral by the end of 2007, a year before the rest of the NHS. All trusts are aiming for an interim target of 85 per cent of admitted and 95 per cent of non-admitted patients by 31 March.

The pioneering trusts have demonstrated that collecting referral-to treatment data is more laborious than collecting data for previous "stage of treatment" targets.

A national "secondary uses services" IT solution - intended to track patients from referral to treatment - had been due to go live in December, but has not been delivered. Trusts have had to adapt prospective patient tracking list systems.

A spokeswoman for South Devon Healthcare Foundation trust, one of the early achievers, said validated 18-week data was unlikely to be available before late February:

"Our systems are not designed to collect referral-to-treatment time data so we've had to develop work-arounds in-house for the existing systems to avoid manual collection as far as possible," she said.

"We haven't got a field to record the 18-week clock start date on our patient administration systems, but we've used a comments field so we can enter the date there."

This date has not always been included, so booking clerks have had to look back through many patients' notes as well as study the notes of all legacy patients to check whether the clock was stopped during their treatment.

Jane O'Neill, head of service development at Countess of Chester Hospital foundation trust, said the December data was not ready due to delays to a national technical solution.

There were also complications with the 18-week clock rules, she said. For example it was unclear what happened if a patient chose a date outside the target.

"Legacy patients are proving difficult as there are a lot of them and the only guidance we have received from the Department of Health is to undertake a manual validation exercise, which would be extremely resource and time-consuming," Ms O'Neill added.

Other early achievers still validating December data include St Helens and Knowsley Hospitals, Taunton and Somerset, Chesterfield Royal Hospital foundation, Bolton Hospitals, East Kent Hospitals, and Doncaster and Bassetlaw Hospitals foundation.

Last week the DH released data for October 2007 on 84 per cent of admitted patients and 96 per cent of non-admitted patients. Of these, 60 per cent of admitted patients and 77 per cent of non-admitted patients were treated within 18 weeks.

Health minister Ben Bradshaw said that several trusts had achieved the 18-week target a year early. These include Yeovil District foundation trust and Blackpool Fylde and Wyre Hospitals trust: "The NHS says it is confident of achieving this year's historic target," he said.

A DH spokeswoman said early achiever trusts had never been expected to have data robust enough to be published in January.

HSJ's Information for Service Transformation conference is on 13 February. See www.hsj-information.co.uk