Foundation trust quality accounts are unreliable, with wide variations in the standard of data used, an Audit Commission study has found.

In a briefing paper, the watchdog said it found a “widespread lack” of comprehensive systems for compiling the accounts, which contain information on the standard of services and how trusts intend to improve them.

It has told almost all foundation trusts they should review data quality.

Neil Childs, director of the commission’s audit practice for health, said quality accounts, or reports, can force trusts to identify their areas of weakness.

But he added: “The reports are only as good as the data that underpins them. Auditors have found some important areas for improvement.”

The study was based on assurance work on 52 foundation trusts’ reports. A third of the reports did not “give a balanced view of performance” as they paid less attention to areas where performance was weaker, the regulator found. However, auditors also found good practice, with some trusts showing strong governance over data quality.

A King’s Fund analysis in January found “variation and a lack of comparability” in 2009-10 quality accounts.