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Surgeon specific mortality in adult cardiac surgery: comparison between crude and risk stratified data
Ben Bridgewater1, Anthony D Grayson, Mark Jackson
1South Manchester University Hospital, Manchester M23 9LT. ben.bridgewater@smuht.nwest.nhs.uk
Insights
Comparing crude versus risk-stratified mortality after coronary artery bypass surgery reveals that crude death rates can be misleading. Risk stratification is crucial for accurate surgeon performance assessment.
Area of Science:
- Cardiovascular Surgery
- Health Services Research
- Medical Statistics
Background:
- Government initiatives aim to publicly disclose individual surgeons' mortality data following clinical governance failures.
- Accurate assessment of surgical outcomes is essential for maintaining public trust and improving patient care.
Purpose of the Study:
- To compare crude mortality rates with risk-stratified outcomes for coronary artery bypass surgery.
- To evaluate the impact of patient risk factors on surgeon-specific mortality data.
Main Methods:
- Retrospective analysis of prospectively collected data from adult patients undergoing first-time isolated bypass graft surgery.
- Utilized EuroSCORE to predict patient mortality and compared it with observed surgeon-specific postoperative mortality.
- Data collected from all NHS centers in North West England performing cardiac surgery between April 1999 and March 2002.
Main Results:
- Analysis included 8572 patients operated on by 23 surgeons, with an overall mortality of 1.7%.
- Observed mortality varied between surgeons (0% to 3.7%), as did predicted mortality (2% to 3.7%).
- A significant proportion of deaths (49%) occurred in lower-risk patients (EuroSCORE ≤ 5), and variability in predicted mortality was largely due to a small number of high-risk patients.
Conclusions:
- Risk-stratified data collection for coronary bypass surgery is feasible, with most patients having low predicted mortality.
- Crude mortality comparisons are misleading and may lead to risk-averse surgical practices.
- Recommended risk-stratified comparisons, focusing on low-risk cases, as a national benchmark for assessing surgeon performance.
Objective:
As a result of recent failures in clinical governance the government has made a commitment to bring individual surgeons' mortality data into the public domain. We have analysed a database to compare crude mortality after coronary artery bypass surgery with outcomes that were stratified by risk.
Design:
Retrospective analysis of prospectively collected data.
Setting:
All NHS centres in the geographical north west of England that undertake cardiac surgery in adults.
Participants:
All patients undergoing isolated bypass graft surgery for the first time between April 1999 and March 2002.
Main Outcome Measures:
Surgeon specific postoperative mortality and predicted mortality by EuroSCORE.
Results:
8572 patients were operated on by 23 surgeons. Overall mortality was 1.7%. Observed mortality between surgeons ranged from 0% to 3.7%; predicted mortality ranged from 2% to 3.7%. Eighty five per cent (7286) of the patients had a EuroSCORE of 5 or less; 49% of the deaths were in this lower risk group. A large proportion of the variability in predicted mortality between surgeons was due to a small but differing number of high risk patients.
Conclusions:
It is possible to collect risk stratified data on all patients undergoing coronary bypass surgery. For most the predicted mortality is low. The small proportion of high risk patients is responsible for most of the differences in predicted mortality between surgeons. Crude comparisons of death rates can be misleading and may encourage surgeons to practise risk averse behaviour. We recommend a comparison of death rates that is stratified by risk and based on low risk cases as the national benchmark for assessing consultant specific performance.