Trusts will be expected to collect information on the success of treatments in a move that could pave the way for more public information about individual clinicians' performance.

From April 2009, hospitals must gather data on patient-reported outcome measures (PROMs).

Guidance in the 2008-09 operating framework says trusts must ask patients to complete short questionnaires before and after hip and knee replacements and operations for hernias and varicose veins.

John Appleby, chief economist at the King's Fund, said the move was 'unbelievably fantastic' and a world first.

He said it would help the NHS assess productivity, which it has previously struggled to measure.

Mr Appleby estimated the first stage of PROMs would cover a quarter of a million patients a year and up to£800m in spending. It could be extended to other procedures if successful.

The move follows a pilot at 24 hospitals and treatment centres in the NHS and independent sector by the London School of Hygiene and Tropical Medicine.

Nick Black, professor of health services research and part of the pilot team, said the trials confirmed the measures were useful.

'We found we could expect to reach 80 per cent of patients and follow up with 80-90 per cent of them. At those levels we feel the information is valid,' he said.

The guidance sets out a range of uses for the data, including helping clinicians benchmark their own performance and researching what treatments work best.

The outcome measures will also be useful for regulators, in clinical audits and 'for patients and GPs exercising choice'.

Professor Black said: 'Provider managers will be able to ask questions of clinicians such as why they're not doing as well as competitors and other providers.

'Commissioning managers will be able to sit down with providers and compare their outcomes with the outcomes of other providers in the area.'

He said it was likely the public would be able to access results for individual hospitals online before long.