Your point that up to £1bn of bills sent by trusts to primary care trusts could be incorrect is misleading.

We made it clear in our report and in separate briefings that the results of the payment by results data quality audits at individual trusts cannot be extrapolated. The samples for the audits are too small and also biased to those specialties where possible anomalies in the data had been identified using our national benchmarker. The only safe figures are the ones quoted in the report - that the errors amounted to£3.5m or 5 per cent of the value of the sample audited.

There was also an error in the table. The healthcare error rate for United Lincolnshire Hospitals was 27 per cent, not 44 per cent. The under/overcharge column should have been blank.

Andy McKeon, managing director, health, Audit Commission