Health Secretary Alan Johnson has written to congratulate chief executives at the 57 NHS organisations that have achieved the most consistent results in yearly assessments.

Co-signed by Healthcare Commission chair Sir Ian Kennedy, the letter has been sent to organisations with top scores in the 2007-08 annual health check that have also achieved good results in previous years. It says: "We want to thank you and your staff personally for all that you have done to achieve this on behalf of patients.

"Your organisation has achieved a level of performance that all trusts should aspire to."

It comes as NHS organisations celebrate the most successful annual health check to date.

Overall performance has continued to improve, with the number of "excellent" scores for quality of services and use of resources increasing by around 10 percentage points compared with last year.

For the first time, more trusts have scored good and excellent than fair and weak. And 42 trusts receive a score of excellent for both parts of the health check, up from 19 last year, and just two in 2005-06.

Case studies

The commission has put together a booklet containing case studies of organisations that have either performed consistently or improved. In the booklet, Sir Ian writes: "We are not claiming that these organisations are now perfect. Indeed, a hallmark of improving organisations is that they are the first to say that they have more to do for their patients and the communities they serve."

The case studies include Heart of Birmingham teaching primary care trust, which is battling against severe health inequalities using a range of initiatives.

Buckinghamshire Hospitals trust is also praised for shaking off the legacy of C difficile outbreaks at Stoke Mandeville hospital between 2003 and 2005.

The trust's C difficile rates are in the lowest third nationally, making it one of the best acutes in the NHS South Central region.

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Best and worst performers

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Annual check finds trusts in rude health

Case study: Salford

Case study: Dorset healthcare foundation trust

Case study: Rotherham foundation trust

HSJ's conference NHS Change Management is on 22 October in London.