Comparative analysis of patient safety using a set of US indicators has heightened concerns about the quality of NHS trust coding, according to a Dr Foster Intelligence study.

The company had planned to publish trust-by-trust comparison of performance on patient safety against nine of the US Agency for Healthcare Research and Quality indicators. But returns from trusts revealed such variance and lack of confidence in secondary level coding that Dr Foster plans to work with a selection of trusts on a study of how to improve safety reporting.

Dr Foster director of strategy Hilary Rowell said it was not clear from the findings whether low reporting of adverse incidents showed a good safety record or poor reporting.

But it was evident that some trusts did not trust their own data. 'The exercise has thrown an interesting light on the patient safety culture in some trusts,' she said.

The findings are part of Dr Foster Intelligence's Hospital Guide, published next week.