After Bristol, the quality and safety of heart surgery has attracted much attention. The media and the public, as well as the profession, have started to look quite carefully at the outcome of heart operations. Heart surgery is exceptional amongst medical specialties in three ways:

• Most heart surgery consists of a handful of operations, and over half of these are just one type of operation: coronary artery bypass grafting (CABG)

• Because these are big operations which carry some risk of death, it is relatively easy to produce figures for the death rate

• Death is a very solid, objective outcome (no-one can argue about it)

For these reasons, heart surgery lends itself easily to analysis. It is not surprising that the specialty has become the first focus of initiatives to measure quality of medical treatment.

Overall, results compare favourably with any in the world. It is an achievement that despite operating on older and sicker patients, the death rate for first time coronary artery bypass is only 2.1% for the nation, and in no hospital does it exceed 4.3%. Hospital results obviously will differ from each other, and there are many reasons for this, ranging from different patient risk profiles, to genuine differences in hospital performances. Nevertheless, the current outcomes are very satisfactory indeed, and the risk of major open heart surgery now compares quite favourably with the risk of relatively less complex general surgical and orthopaedic procedures.

Heart surgery is, without any doubt, the most studied, monitored and audited specialty. The current monitoring systems, though not perfect, make it very unlikely that poor performance will go undetected for any length of time. The lessons of Bristol have been learnt by the profession and efforts are constantly made to improve quality control in the specialty.

The results of coronary bypass surgery in England are as good as anywhere in the world, but inevitably there is quite a variation in results between hospitals. Experience from North America has shown that this variation is neither surprising nor unusual. For example, between 1995 and 1998 the percentage of patients dying following coronary surgery in different hospitals in New York State ranged from 0.62 – 4.56% (Average 2.27%) compared with 0.8 – 4.6% in the UK for 1998-2000 (Average 2.3%). A comparison of data between UK and USA national cardiac surgical databases shows that the survival rates for coronary surgery the UK and US are almost identical at 97.6% and 97.3% respectively in 1999. These are extremely good results, but we must remember that heart surgery is a highly technical, complex business and although we can achieve a relatively low risk for most patients we can never reduce this to no risk.

There is clear evidence that using an artery, called the internal mammary artery, from inside the chest, rather than a vein from the leg, to bypass the most important coronary artery in the heart reduces the risk of surgery. In 1999 in the UK 88.5% of patients received at least one internal mammary artery graft as opposed to 79% in the US.  Similarly, improved surgical technique and selection of the right patients has reduced the mortality for repeat coronary surgery in the UK from 9.6% in 1997 to 5.5% in 1999. But there have been improvements in other areas as well. We are treating diabetics better. The mortality for diabetics undergoing surgery has fallen from 5.7% in 1996 to 3.2% in 1999 – a 40% improvement in outcome.

This depends on the quality of the league tables and the information from which they are constructed. It is easy to place hospitals in order of death rate after a particular operation, but it is much more difficult to interpret such league tables intelligently.

The most important feature in any league table is that the data on which it is based are accurate and complete, and, sadly, this is rarely the case. The second most important feature is that the data should be risk-stratified (in other words, a measure of how old and sick the patients are should be included) so that the league table is fair and does not penalise hospitals which are prepared to accept high-risk patients.

League tables, even if they are accurate and risk-stratified, invariably mean that there is always a hospital at the bottom of the league. If we decide to shut this hospital down, the next hospital will end up as the bottom hospital and, if we carry this argument to its logical conclusion, there will only be one hospital (perhaps only one surgeon!) left to carry the country's heart surgery workload, an impossible task.

Another feature of league tables is that the easiest way to move up the table is to refuse high risk patients, but this is bad for patients because it is often these very patients who stand to gain most from operations. Although league tables are in vogue, with ever-increasing demands for public disclosure of data and greater openness, it is important that their limitations and inherent problems are recognized.

Most patients are probably not interested in where exactly their hospital is in the league table, but they are interested, and rightly so, in knowing that their hospital constantly monitors its performance and acts immediately if there is evidence that it is not doing well.

To achieve, a hospital needs to have accurate information on the number of operations it caries out, who does them, their nature and their outcome (at the very least survival rates). The hospital also needs to have some risk information about its patients, and agreed limits for acceptable performance. Once a hospital has all this information readily available, it must continuously monitor its results to ensure that the standard is met or exceeded. Finally, the hospital should have a robust mechanism for dealing with and swiftly correcting any underperformance that may occur.

In other words, this approach would build quality monitoring into the local fabric of the hospital management. If all hospitals had these mechanisms in place, league tables would become largely unnecessary. The Society of Cardiothoracic Surgeons of Great Britain & Ireland (SCTS) has begun a Quality Accreditation Programme

The Department of Health has Hospital Episode Statistics in which which were designed for measuring clinical activity in hospitals. It collects basic information such as age, postcode, diagnosis and treatment or operation and whether the patient was discharged alive or dead from hospital. The system was not designed to collect detailed clinical data. Nevertheless it can be used for measuring basic performance. Unfortunately because people with more of a clerical than clinical training collect the information and hospital notes can be difficult to interpret, the HES data can be quite inaccurate when complex procedures are coded in the system. Nevertheless it provides a basic tool for the Department of Health and organizations like Dr Foster to scan hospital results. Dr Foster try to compensate for differences in patient populations at different hospitals by taking into account the effects of age, gender, urgency of operation and social status or deprivation which is the best that can be expected from the data available, but many other conditions such as underlying heart function, lung function, smoking history, diabetes, obesity, high blood pressure, kidney function and other vascular conditions all have an impact on the risk of a heart operation. These factors must all be taken into account when calculating surgical risk, particularly if meaningful comparisons between units or surgeons are to be made. 

The SCTS monitors the outcome of a number of key operations in both adult cardiac, adult thoracic and paediatric cardiac surgery. This is done by hospital and also by consultant surgeon. When under performance is detected, the hospital is informed of this so that action can be taken. The SCTS usually helps identify the sources of the problem and ways to correct the problem. This monitoring is continuous.