Your chances of survival, or receiving any better treatment, are no better in one of the larger, specialist units beginning to crop up.

Health care has been concentrating on setting up more specialist units on the theory that the more physicians and staff perform the same procedures, the better the outcome. Studies had also indicated that this was the case. A specialist unit is one which carries out more than 200 procedures of the same operation a year.

But researchers at the University of York in England have discovered that these studies may have been wrongly interpreted. Observations of better outcomes at the specialist units are not good science, and had not allowed for the mix of cases being treated.

As an example, they analyzed seven studies from the US which had looked at specialist coronary bypass units over a 20-year period until 1992. Once they adjusted for all factors, the mortality rate of the patients at the specialist units came closer to the average. For instance, specialist units may have been able to treat more patients simply because they dealt only with less serious cases; not surprisingly, the mortality rate among those patients was better.

Equally, the standards of bypass surgery may be improving everywhere but not publicized at the general centres.

While the researchers accept that their findings cannot necessarily be applied to other procedures, they hope that health policymakers may reconsider their headlong dash towards the specialist unit (BMJ, July 15, 1995).