Stuart W Grant

How does EuroSCORE II perform in UK cardiac surgery; an analysis of 23 740 patients from the Society for Cardiothoracic Surgery in Great Britain and Ireland National Database

Objective The original EuroSCORE models are poorly calibrated for predicting mortality in contemporary cardiac surgery. EuroSCORE II has been proposed as a new risk model. The objective of this study was to assess the performance of EuroSCORE II in UK cardiac surgery. Design A cross-sectional analysis of prospectively collected multi-centre clinical audit data, from the Society for Cardiothoracic Surgery in Great Britain and Ireland Database. Setting All NHS hospitals, and some UK private hospitals performing adult cardiac surgery. Patients 23 740 procedures at 41 hospitals between July 2010 and March 2011. Main outcome measures The main outcome measure was in-hospital mortality. Model calibration (Hosmer–Lemeshow test, calibration plot) and discrimination (area under receiver operating characteristic curve) were assessed in the overall cohort and clinically defined sub-groups. Results The mean age at procedure was 67.1 years (SD 11.8) and 27.7% were women. The overall mortality was 3.1% with a EuroSCORE II predicted mortality of 3.4%. Calibration was good overall but the model failed the Hosmer–Lemeshow test (p=0.003) mainly due to over-prediction in the highest and lowest-risk patients. Calibration was poor for isolated coronary artery bypass graft surgery (Hosmer–Lemeshow, p<0.001). The model had good discrimination overall (area under receiver operating characteristic curve 0.808, 95% CI 0.793 to 0.824) and in all clinical sub-groups analysed. Conclusions EuroSCORE II performs well overall in the UK and is an acceptable contemporary generic cardiac surgery risk model. However, the model is poorly calibrated for isolated coronary artery bypass graft surgery and in both the highest and lowest risk patients. Regular revalidation of EuroSCORE II will be needed to identify calibration drift or clinical inconsistencies, which commonly emerge in clinical prediction models.

Clinical registries: governance, management, analysis and applications.

Clinical registries will have an increasingly important role to play in health-care, with a number already established in cardiac surgery. This review covers the fundamentals of establishing and managing clinical registries, including legal and ethical frameworks along with intellectual property attribution. Also discussed are important issues relating to the processing of data, data extraction and conducting analyses using registry data.

Logistic risk model for mortality following elective abdominal aortic aneurysm repair

The aim was to develop a multivariable risk prediction model for 30‐day mortality following elective abdominal aortic aneurysm (AAA) repair.

Evaluation of five risk prediction models for elective abdominal aortic aneurysm repair using the UK National Vascular Database

There is no consensus on the best risk prediction model for mortality following elective abdominal aortic aneurysm (AAA) repair. The objective was to evaluate the performance of five risk prediction models using the UK National Vascular Database (NVD).

National risk prediction model for elective abdominal aortic aneurysm repair.

Mortality results for elective abdominal aortic aneurysm (AAA) repair are published by the Vascular Society of Great Britain and Ireland. These mortality results are not currently risk‐adjusted. The objective of this study was to develop a national risk prediction model for elective AAA repair.

A comparison of outcomes between bovine pericardial and porcine valves in 38 040 patients in England and Wales over 10 years

OBJECTIVES Biological valves are the most commonly implanted prostheses for aortic valve replacement (AVR) surgery in the UK. The aim of this study was to compare performance of porcine and bovine pericardial valves implanted in AVR surgery with respect to survival and reintervention-free survival in a retrospective observational study. METHODS Prospectively collected clinical data for all first-time elective and urgent AVRs with or without concomitant coronary artery bypass graft (CABG) surgery performed in England and Wales between April 2003 and March 2013 were extracted from the National Institute for Cardiovascular Outcomes Research database. Patient life status was tracked from the Office for National Statistics. Time-to-event analyses were performed using log-rank tests and Cox proportional hazards regression modelling with random effects/grouped frailty for responsible cardiac surgeons. RESULTS A total of 38,040 patients were included (64.9% bovine pericardial; 35.1% porcine). Patient characteristics were similar between the groups. The median follow-up was 3.6 years. There was no statistically significant difference in survival (P = 0.767) (the 10-year survival rates were 49.0 and 50.3% in the bovine pericardial and porcine groups, respectively) or reintervention-free survival. The adjusted hazard ratio for porcine valves was 0.98 (95% confidence interval 0.93-1.03). Sensitivity analysis in small valve sizes showed no difference in reintervention-free survival. After adjustment, there was some evidence of a protective effect for porcine valves in relatively younger patients (P = 0.075). CONCLUSIONS There were no differences in reintervention-free survival between bovine pericardial and porcine valves used in first-time AVR ± CABG up to a maximum of 10 years.

A technical review of the United Kingdom National Adult Cardiac Surgery Governance analysis 2008-11

The Society for Cardiothoracic Surgery in Great Britain and Ireland (SCTS) has published named mortality data since 2001. The importance of accurate and robust clinical outcome reporting has been emphasized by a number of high-profile cases in England. In this article, we give a technical review of the United Kingdom National Adult Cardiac Surgery Governance Analysis 2008-11. The statistical and analytical assumptions and methods are discussed in order to add an additional layer of transparency to the clinical governance process and precipitate scrutiny with the aim of optimizing future analyses.

Validation of the EuroSCORE II: should we be concerned with retrospective performance?

We congratulate Chalmers et al. [1] on their recent article that demonstrates the potential validity of EuroSCORE II. As a result of numerous contemporary external validations, it is now widely accepted that the original EuroSCORE is obsolete for contemporary cardiac surgery [2]. Before EuroSCORE II can be adopted for either future clinical or governance applications, it is important that it is independently validated. Chalmers et al. used data from a single unit between January 2006 and March 2010 for their validation study. We would, however, raise a note of caution around the study period. EuroSCORE II was developed on data from patients who underwent surgery between May 2010 and July 2010 and is presumably intended for prospective use [3]. The most recent data included in Chalmers’ validation study is over 2 years old, and performing model validation over a time period as wide as 5 years is potentially misleading. In the same way that the original EuroSCORE models have systematically drifted from the acceptable levels of model calibration with increasing time, reversing the arrow of time might have a similar shifted effect due to dynamic changes in the patient characteristics, case-mix and baseline risk relative to those in the EuroSCORE II patient cohort [4]. Hence, if the model performed badly in 2006 but adequately in 2010, then mixed inferences might be drawn in an overall study period validation. Also, to add clarification to Chalmers’ paper, one of the models analysed in this study was a modified EuroSCORE model developed by the Society for Cardiothoracic Surgery (SCTS) in Great Britain and Ireland. This model was a complex recalibration of the original logistic EuroSCORE updated using registry data collected between 2004 and 2007. The modified EuroSCORE, like the original EuroSCORE models, now demonstrates poor calibration for contemporary cardiac surgery. The SCTS has recognized this and consequently no longer uses this model. Interestingly, despite model calibration deteriorating over time, discriminatory ability has remained consistently good. We also note with interest that Chalmers et al. demonstrate different results in the isolated aortic valve replacement subgroup from those in a separate large multicentre validation study that includes all NHS hospitals in the UK [5]. Namely, the c-statistic was 0.69 (95% confidence interval [CI] 0.57–0.79), which is below the 0.7 threshold for acceptable performance. However, in the national study, it was 0.77 (95% CI 0.67–0.77), which is considered acceptable. Differences in the results for model validation studies within subgroups could be attributable to variation between units and analytical subtleties. Nevertheless, these important patient subgroups warrant further investigation, possibly with a view to introducing procedure-specific models.

Creating transparency in UK adult cardiac surgery data

Cardiac surgeons in the UK have openly published their outcome data at hospital and individual surgeon levels since 2005. Publication of these data has been associated with a decreased risk of inhospital mortality following cardiac surgery despite more high risk patients undergoing surgery. Cardiac surgeons in the UK have now developed a series of different tools with the aim of further improving transparency, facilitating access to clinical data and driving quality improvement. These tools make contemporary high quality data from the National Adult Cardiac Surgery Audit (NACSA) database available to various different interest groups. This article describes the tools that have been developed and details how they can be accessed. The National Health Service (NHS) commissioning Board has recently announced that results for 10 specialties will be published at an individual team level by Summer 2013.1 The public inquiry into the events at the Mid Staffordshire NHS Foundation Trust has also recommended that clinical outcomes should be published more widely to assure the quality of healthcare services and help prevent further failures of clinical governance.2 UK cardiac surgeons first published their results in 2005 following a request by the Guardian newspaper under the newly introduced Freedom of Information Act.3 Following on from this, the Society for Cardiothoracic Surgery in Great Britain and Ireland (SCTS) has continued to conduct governance analyses and publish results at hospital and individual surgeon levels. This was done initially in conjunction with the Care Quality Commission but more recently results have been published on the SCTS website (http://www.scts.org/patients).4 The outcomes published in the public domain are based on an analysis of ‘all’ cardiac surgery over a 3-year window of …

Authors' reply: Logistic risk model for mortality following elective abdominal aortic aneurysm repair (Br J Surg 2011; 98: 652–658)

Sir I wish to congratulate Professor U. Güller and colleagues for their impressive work on the negative appendicectomy and perforation rates following laparoscopic appendicectomy. I wish to draw the authors’ attention to some comments. This study was based on a prospective database including 7964 patients who underwent laparoscopic appendicectomy, rather than on the actual number of patients having surgery for a preoperative diagnosis of appendicitis. This probably explains their very low incidence (6·4 per cent) of negative appendicectomy. For instance, any female patient with a gynaecological pathology such as ruptured ovarian cyst would have followed a different treatment pathway and therefore not been included in this analysis. Another bias towards having a low negative appendicectomy rate is that the diagnosis of appendicitis was based on a subjective perception of macroscopically abnormal appendix, rather than more objective microscopic findings1. It seems that an inversely proportional correlation between negative appendicectomy and perforation rates exists, such as among the female patients in this article. Although some suggest that perforated and non-perforated appendicitis may simply be fundamentally different diseases2, we should not aim for reducing the negative appendicectomy rate as a favourable clinical endpoint and instead keep a low threshold for laparoscopic exploration in case of equivocal diagnosis3. Finally, although clinical examination remains paramount to the diagnosis of appendicitis, I agree with the authors that the widespread availability of radiological imaging could have a favourable impact on the accuracy of the preoperative diagnosis, especially in elderly patients4. C. Berney Bankstown-Lidcombe Hospital, Bankstown, New South Wales, Australia (e-mail: berneycr@hotmail.com) DOI: 10.1002/bjs.7663