BMJ  2005;330:44 (1 January), doi:10.1136/bmj.330.7481.44

Letter

Paediatric cardiac surgical mortality after Bristol

Authors' reply

EDITOR—Parry et al call for clarity of our methods for risk adjustment. We adjusted by type of operation, by incorporating the 11 open procedure groups as factors into our regression model. The use of procedure groups for risk adjustment is in line with another published method.¹ In contrast, recently published centre comparisons based on the central cardiac audit database were not risk adjusted.²

Gibbs et al and Morris and Archer on bmj.com remain concerned by the lack of accuracy of hospital episode statistics.³ Work commissioned by the Bristol inquiry showed reasonable agreement between these and the UK cardiac surgical register. Hospital episode statistics also recorded 99% of 30 day postoperative deaths in hospital for the procedures of interest.⁴ Morris and Archer confirm that the Oxford centre was approached by the Department of Health in 2001 on the basis of both hospital episode statistics data and cardiac surgical register returns since 1995, in which it was thought that it was an outlier with respect to transposition of the great arteries in infants.³ Oxford was also aware of a possible downturn in its results and consequently ceased such surgery in 2000 (J Morris, personal communication).

Differences between analyses of the central cardiac audit database and our own are not necessarily inconsistent.

Firstly, we look only at mortality in hospital, and results published from the database include all perioperative deaths.

Secondly, hospital episode statistics lack an indicator to specify whether an operation is open, and so this must be inferred from the operation code. We exclude any operations that could be either open or closed, which could account for the alleged shortfall. However, we also examined mortality in a group of 11 well defined open procedures, which gave similar results between centres.

Lastly, Gibbs et al provide central cardiac audit database results for a different time. Oxford has confirmed to us that it stopped transposition of the great arteries because of several deaths in late 1999 (hence included in our analysis but not included in figures from the central cardiac audit database) and early 2000 (J Morris, personal communication).

Hospital episode statistics is the only available database spanning our period of analysis from 1991 to 2002. It is coded independently of clinicians and is available for public scrutiny. Further collaborative work to identify and correct inconsistencies between hospital episode statistics and clinical datasets might be a useful consequence of our work and could enhance the credibility of both sources of data.

p.aylin{at}imperial.ac.uk, Dr Foster Unit at Imperial College London, Department of Epidemiology and Public Health, St Mary's Campus, Imperial College, London W2 1PG

Dr Foster Unit at Imperial College London, Department of Epidemiology and Public Health, St Mary's Campus, Imperial College, London W2 1PG

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Competing interests: The work was funded by Dr Foster Limited. BJ served on the panel for the Bristol Royal Infirmary inquiry. PA was an expert witness for the inquiry.

References

1. Jenkins K, Gauvreau K, Newburger J, Spray T, Moller J, Iezzoni L. Consensus-based method for risk adjustment for surgery for congenital heart disease. J Thorac Cardiovasc Surg 2002;123: 110-8.[Abstract/Free Full Text]
2. Gibbs JL, Monro JL, Cunningham D, Rickards A. Survival after surgery or therapeutic catheterisation for congenital heart disease in children in the United Kingdom: analysis of the central cardiac audit database for 2000-1. BMJ 2004;328: 611-5.[Abstract/Free Full Text]
3. Morris J, Archer N. Paediatric cardiac surgical mortality. Electronic response to: Paediatric cardiac surgical mortality in England after Bristol. bmj.com 2004. http://bmj.bmjjournals.com/cgi/eletters/329/7470/825#77793 (accessed 16 Dec 2004).
4. Aylin P, Alves B, Best N, Cook A, Elliott P, Evans SJW, et al. Comparison of UK paediatric cardiac surgical performance by analysis of routinely collected data 1984-96: was Bristol an outlier? Lancet 2001;358: 181-7.[CrossRef][ISI][Medline]

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Relevant Article

Survival after surgery or therapeutic catheterisation for congenital heart disease in children in the United Kingdom: analysis of the central cardiac audit database for 2000-1

John L Gibbs, James L Monro, David Cunningham, and Anthony Rickards
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