The effects of surgical volumes and training centre status on outcomes following total joint replacement: analysis of the Hospital Episode Statistics for England

Objective: Previous work from other countries has shown a significant inverse relationship between the number of some surgical procedures undertaken in a hospital and in an adverse outcomes. In the light of the changing nature of the provision of joint replacements in the United Kingdom, we have examined the effects of surgical volumes and the presence/absence of training centre status, on outcomes following total joint replacement (TJR) in England. Methods: Analysis of the Hospital Episode Statistics (HES) on all hip/knee joint replacements in English National Health Service (NHS) trusts between financial years 1997 and 2002. Exposures explored were the volume of hip/knee replacements per annum in an NHS trust, training centre status and whether the admission was routine or emergency. Four surrogate measures of adverse outcome were assessed: 30-day in-hospital mortality, length of stay in hospital, readmission within a year and surgical revision within 5 years. Age and sex were controlled for as potential confounders. Results: Data from a total of 281360 hip replacements and 211099 knee replacements were examined. HES data show that the numbers of TJRs performed in low volume trusts are small and decreasing. Adverse outcomes were also uncommon. Nevertheless, significant associations between adverse outcomes and low volume units, and better outcomes in training centres, were detected. For example, the odds ratio (OR) for in-hospital death within 30 days of hip replacement in trusts doing < 50 hip/replacements per annum is 1.98 [95% confidence interval (95% CI) = 1.13-3.47] compared with trusts doing 251-500 operations/annum. Similarly, surgery in non-training centres is more likely to result in mortality than that in training centres (OR = 1.25, 95% CI = 1.05-1.48). The examination of surgical revision indicated adverse outcomes in higher volume units; this may be due to case-mix. Conclusion: In England, there are fewer adverse events following TJR in high volume centres and in orthopaedic training centres. Standardization of procedures may account for this finding. The data have implications for private practice in the United Kingdom and for the current move to undertake TJRs in Independent Sector Treatment Centres.