DATA BRIEFING - CLINICAL QUALITY

Published: 09/12/2004, Volume II4, No. 5935 Page 23

There is strong evidence to suggest hospitals which do higher volumes of particular operations achieve better outcomes. Despite this, many NHS patients in England are not treated in hospitals that meet recommended volume levels.

Chart 1 shows the level of improvement in mortality comparing surgery in higher volume hospitals with lower volume hospitals.

Vascular surgery is one area in which high volumes have been shown to benefit patients. The chart shows a 58 per cent reduction in mortality following repair of abdominal aortic aneurysm (AAA) in high-volume hospitals compared with those doing fewer than six each year.

In the US, the National Quality Measures Clearing House, sponsored by the Department of Health and Human Services, has set quality thresholds for volume of AAA repairs at 10 operations a year (minimum) and 32 operations a year (maximum).

The Michigan Health and Safety Coalition, which sets standards for local healthcare providers, recommends that patients only be referred to hospitals doing at least 20 operations a year.

But many people in England continue to be treated in hospitals with significantly lower volumes. The second chart shows the distribution of elective AAA operations by the number of procedures. The figures show that up to one in four operations take place in hospitals with less than one such operation every other month and 15 per cent take place in hospitals with less than one every four months.

While there may be unavoidable reasons for an emergency operation to be performed in a lowvolume hospital, it is surprising that so many of the elective operations are. On the strength of the evidence, it would be reasonable to expect more patients to be referred to high-volume centres.

The third chart shows the same figures - but for reconstruction of carotid artery. Again, many elective procedures are taking place in hospitals with relatively low volumes.

One reason why many hospitals maintain vascular surgery services even at low volumes is to be able to maintain skills to support an emergency service. Commissioners have often been willing to support these decisions.

As we move into a system driven by patient choice and GP commissioning, it will be interesting to see the extent to which elective patients are redirected to high-volume centres. If this does not happen, it will raise questions about the effectiveness of patient choice as a mechanism to enhance clinical quality.

Roger Taylor is research director of health information specialists Dr Foster.