Jeremy Laurance: The failings of the NHS have been exposed

You only have to listen to the choice of language to understand the scale of the scandal exposed at Stafford Hospital. In the five-year history of the Healthcare Commission, the inspectorate never before used the word "appalling" about any NHS institution, and there has been no shortage of candidates.

From Maidstone and Tunbridge Wells, where at least 90 patients died between 2004 and 2006 in the worst outbreak of Clostridium difficile yet recorded, to Cornwall Partnerships Trust which ran homes where people with learning disabilities were subjected to years of bullying, harassment and physical ill-treatment, the failings of the NHS have been repeatedly exposed.

But Stafford is the worst. Although the Healthcare Commission could not say how many patients died as a result of the chaotic emergency service, we do know the hospital's mortality rate has been substantially higher than the national average for almost a decade, and perhaps longer.

There can be many explanations for a high death rate – chance variation, older or sicker patients – but there can be no excuses for failing to investigate it. Yet even after the commission raised its initial enquiries in 2007, the trust board insisted there was a problem with the "clinical codings" which meant the data could not be trusted.

As Sir Bruce Keogh, NHS medical director for England, said yesterday, there is a "moral, professional and social responsibility" on everyone in the NHS to know "what they are doing and how well they are doing it". If you can't answer the question, he said, you shouldn't be doing the job.

Until recently, it has been difficult to ask it because the NHS has measured the process of care (how many patients treated) but not the outcomes (how many cured). Now that information is becoming available. Sir Bruce pledged yesterday that death rates would be published. For the past 18 months, the Healthcare Commission has been operating a new alert system, based on mortality rates, which triggers inquiries when they rise above a certain level.

In the first year, the commission responded to 50 alerts, mostly satisfactorily explained by the trusts involved. But in about 20, the commission warned the trusts to keep a closer eye on their death rates.

Now, Stafford has been caught. It used to be said that doctors buried their mistakes. For many years that is what happened in Stafford. Now, the commission has spotted the disaster and exposed it. The message of its report is that in the modern NHS there is no place to hide mistakes. Shocking as it is, the outcome of this scandal could be good news for patients.