Paediatric heart units that carry out a high number of operations have lower deaths rates than those with a low volume of cases. David Spiegelhalter, a scientist at the Institute of Public Health in Cambridge, analysed voluntary surgical returns and hospital episode statistics relating to 12 hospitals carrying out heart surgery on children from 1991 to 1995.
Dr Spiegelhalter found that a hospital carrying out 120 open heart operations on children less than a year old had a mortality rate 25 per cent lower than a hospital carrying out 40 such operations.
But this alone, does not explain the high death rates, which was a low-volume centre. Less than a fifth of the excess deaths at the Bristol Royal hospital during the early 1990s can be attributed to the fact that it performed relatively few operations.
Dr Spiegelhalter says caution is needed in interpreting his findings because the data sources are not of a high quality and rely on individual hospital reporting rates. He says the policy lessons to be drawn from the study are unclear and that it does not necessarily follow that concentrating resources in fewer centres will lead to lower death rates.