Almost 90 per cent of trusts are failing the accident and emergency indicator on unplanned reattendances, while all acute providers failed to keep their single longest wait below six hours.

The figures are the first to show performance against new government measures.

Experimental data for April, the month the indicators were introduced, shows massive variation in performance, with some extreme outliers being blamed on data quality.

In total 88 per cent of trusts had unplanned reattendance of more than 5 per cent – the “bottom line”. More than half reported rates above 7 per cent.

Less than half of trusts achieved a median time to treatment by a decision making clinician within 60 minutes. Taunton and Somerset Foundation Trust, which recorded a time of 551 minutes, blamed it on a problem with a computer system which had now been corrected. 

Just 28 per cent achieved the time to initial assessment indicator, which requires the 95th percentile of patients arriving by ambulance to be assessed within 15 minutes. Ten trusts reported waits of more than 23 hours, including Croydon Health Services Trust.

Croydon’s director of acute operations Richard Parker said as patients were triaged before they were added to the IT system, the initial assessment took place before the time of arrival was recorded. Analysis by the NHS Information Centre had therefore assumed they had arrived the previous day and added on 1,440 minutes.

Issues with data led the DH to change the way organisations will be performance managed against the indicators in June. Monitor has also removed them from its compliance framework for foundation trusts.

Performance was better against the indicator for patients who left without being seen, which saw 90 per cent of trusts achieve a rate of less than 5 per cent.

Health secretary Andrew Lansley said he expected trusts to use the data in a “positive” way to improve services.

College of Emergency Medicine president John Heyworth said it was “early days” for the indicators but they were starting to identify areas for improvement.