Comparison of UK paediatric cardiac surgical performance by analysis of routinely collected data 1984-96: was Bristol an outlier?

Background Reports of high mortality after paediatric cardiac surgery at th e Bristol Royal Infirmary, UK, led to the establishment of an independent p ublic inquiry. A hey question was whether or not the mortality statistics i n Bristol were unusual compared with other specialist centres. To answer th is question, we did a retrospective analysis of mortality in the UK using t wo datasets. Methods Data from the UK Cardiac Surgical Register (CSR; January, 1984, to March, 1996) and Hospital Episode Statistics (HES; April, 1991, to December , 1995) were obtained for all 12 major centres in which paediatric cardiac surgery is done in the UK. The main outcome measure was mortality within 30 days of a cardiac surgical procedure. We estimated excess deaths in Bristo l using a random-effects model derived from the remaining 11 centres. Addit ionally, a sensitivity analysis was done and case-mix examined. Findings For children younger than 1 year, in open operations, the mortalit y rate in Bristol was around double that of the other centres during 1991-9 5: within the CSR, there were 19.0 excess deaths (95% interval 2-32) among 43 deaths; and in HES, there were 24.1 excess deaths (12-34) among 41 death s recorded. There was no strong evidence for excess mortality in Bristol fa r closed operations or for open operations in children alder than 1 year. Interpretation Our results suggest that Bristol was an outlier, and we do n ot believe that statistical variation, systematic bias in data collection, case-mix, or data quality can explain a divergence in performance of this s ize.