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National Oesophago-Gastric Cancer Audit

The aim of the National Oesophago-Gastric Cancer Audit is to examine the overall quality of care for oesophago-gastric cancer in the UK. In particular, it looks at patterns of treatment and what determines them; compliance with key process standards, such as the use of staging investigations and outcomes of surgery and other treatment, including peri-operative mortality, lymph node yields and resection margin status.

It is funded by the Healthcare Quality Improvement Program (HQIP) and is a collaboration between five organisations:

  • AUGIS
  • British Society of Gastroenterology
  • Royal College of Radiologists (RCR)
  • Clinical Audit and Registries Management Service (CARMS) of NHS Digital
  • Clinical Effectiveness Unit of the Royal College of Surgeons of England / London School of Hygiene and Tropical Medicine (CEU)

To view previous NOGCA Annual Reports, visit the NOGCA website.

NOGCA

NOGCA Report 2020

View 2020 Report

SWORD

Background 2020

The 2020 surgical outcome information was provided by the National Oesophago-Gastric Cancer Audit (NOGCA).  The audit was designed to look at the way NHS trusts manage patients with stomach or oesophageal cancer in England and Wales.

This website provides information about the number of operations performed on patients diagnosed with stomach or oesophageal cancer in English specialist cancer centres, and by individual surgeons.  The outcomes of these operations are described in terms of the proportion of patients who died within 30 days and 90 days of the operation (postoperative mortality rates).

The information about NHS organisations was produced using data from patients diagnosed between 1 April 2016 and 31 March 2019.  For individual surgeons, the information was produced using data from patients diagnosed over five years, between 1 April 2014 and 31 March 2019.  The longer time period allowed a greater number of patients to be included, which made the statistics more robust.

This year, we publish outcome information on 34 specialist cancer centres (NHS trusts) in England and over 150 consultants.  Differences in the postoperative mortality rates of the cancer centres (NHS trusts) and the surgeons were examined using funnel plots.  These plots are a widely used method to graphically present surgical outcomes and illustrate how the mortality rates are expected to vary between organisations and surgeons given the influence of random variation.  Using these plots enables people to see whether the outcomes are within the expected range given the overall national rate.

In looking at this information, it is important to remember that the surgical outcomes for NHS trusts and surgeons may vary because of differences in patient factors such as their age, sex and the number of other illnesses patients have – known as co-morbidities.  Some surgeons might be operating on higher risk patients with complex health needs like diabetes or respiratory problems.

The results show that the 30-day and 90-day postoperative mortality rates for all NHS trusts were within the range expected taking into account the variation in patients treated.  The risk-adjusted 90-day postoperative mortality rate for one surgeon was above the expected range, identifying them as a potential outlier.

Data Collection 2020

The information on surgical outcomes for the English NHS trusts was derived from data on patients diagnosed with oesophageal or stomach cancer between 1 April 2016 and 31 March 2019 (three years of data).  For the individual surgeons, the information was produced using data from patient diagnosed over five years, between 1 April 2014 and 31 March 2019.  The patient information was submitted by hospital staff to the Audit via a secure, web-based data collection system and, for most patients, the Audit received complete data on their disease and the variety of treatments given.  Information on whether a patient died after surgery was obtained from the surgeons and from the Office for National Statistics (ONS) death register.

For further details about how the audit collects patient information, please visit the website of the National Oesophago-Gastric Cancer Audit:  https://www.nogca.org.uk

Methods of Analysis 2020

Risk adjustment method

It is common for surgical outcome information to be risk-adjusted because the characteristics of patients treated by surgeons vary, and the outcomes of care will be influenced by these characteristics.  For example, on average, outcomes are worse for sicker patients.

The postoperative mortality figures for the NHS trusts and surgeons were adjusted for several patient characteristics: age at diagnosis, performance status, ASA grade, presence of significant comorbidities, tumour site, pathology T stage, number of positive nodes and receipt of neoadjuvant therapy.

We used the same patient characteristics in the risk adjustment for both the 30- and 90-day mortality rates.  The risk adjustment process works by taking into account the overall average mortality rate and the distribution of deaths across the NHS trusts / consultants.  Because of this, the process will occasionally produce a slightly higher estimate of the 30-day mortality rate than the 90-day mortality rate.  This quirk of the risk adjustment process is related to the degree of certainty with which we can estimate surgical outcomes.  As explained below, we use a control chart technique to take into account the degree of certainty in these estimates when assessing surgical outcomes.

 

Using control charts to check outcomes are within the expected range

Surgeon outcome information will always differ from the outcome figures published at a national level because of random variation – some NHS trusts will have higher values and some lower.  This variation is not communicated when figures are ranked.  Consequently, these NHS trust or surgeon figures should not be ranked.  Presenting this information in the form of a league table of surgeon outcomes would be misleading and lead to wrong conclusions about an individual surgeon’s performance.

The variation in postoperative mortality rates was examined using a graph known as a funnel plot.  The benefit of this approach is that it shows whether the outcomes for individual NHS trusts or surgeons differ from the national average by more than would be expected due to random fluctuations.  Random variation will always affect outcome information like mortality rates, and its influence is greater among small samples.

On these funnel plots, each dot represents an NHS trust or a consultant and they are compared against the national average.  The national average for 30-day and 90-day postoperative mortality over the three year period covered by the analysis was 1.73% and 3.27%, respectively; over the five year period, the national averages were 1.73% and 3.16%, respectively.  The vertical axis indicates the outcome, with dots higher up the axis showing NHS trusts or consultants with higher mortality rate. The horizontal axis shows surgical activity with dots further to the right showing the NHS trusts / consultants who perform more operations.

The funnel plot includes two control limits to define the range within which we would expect NHS trust or surgeon outcomes to lie.  Following convention, we use 99.8% control limits.  It is unlikely for an NHS organisation or surgeon to fall beyond these limits solely because of random variation (a 1 in 500 chance).  If the outcome figures for an NHS trust or surgeon fell outside the outer limits, there could be a systematic reason for the higher or lower rate, and they would be flagged as an outlier for further investigation.  The main cause of variation within the control limits is likely to be random variation.

The expected range of outcomes for a given number of operations (the sample size) is shown on the funnel plots by the different coloured regions.  We would expect the figures of the NHS trusts or consultants to fall within the green area if their outcomes only differed from the national average because of random variation.

None of the NHS trusts included in the analysis had a risk-adjusted mortality rate above the 99.8% control limit. One surgeon had a risk-adjusted 90-day mortality rate above the 99.8% control limit, identifying them as a potential outlier.

Future Reporting of Surgeons Outcomes 2020

The publication of outcomes for consultant surgeons complements our previous work in publishing clinical audit findings by NHS trust and informing patients about the standard of care that they can expect to receive.

Postoperative mortality is a fundamental aspect of care and a reflection of the safety of the procedure, which is influenced by a combination of factors including the preparation for surgery, the actual operation and the recovery process. However, publishing consultant-level mortality represents only a first step. In the future, we expect to report on a wider set of outcomes for patients.

The reporting of clinical outcomes is only as good as the data that are submitted to the audit. It is the responsibility of each NHS trust and consultant to make sure that all relevant data are submitted in time, so that the reporting of consultant outcomes appropriately reflects the practice of individual surgeons.

In order to improve data quality further, we encourage all surgeons to:

  • Make sure all eligible patients are entered into the Audit
  • Submit surgical records for all patients with oesophageal or stomach cancer
  • Ensure the data items have been completed when submitted, including treatment intent and patient characteristics
  • Record all details of the patient’s co-existing medical conditions and other perioperative treatments (eg, chemotherapy)
  • Check that the uploaded data reflects their practice.