Explanatory Notes

Definitions, inclusion criteria and explanations for trust results

Management of patients with high grade dysplasia

Management of patients with oesophago-gastric (OG) cancer

Outcomes for OG cancer patients who have curative surgery

Interpretation of funnel plots

 

Management of patients with high grade dysplasia

This section provides information on the diagnosis and treatment of patients with high grade dysplasia (HGD) of the oesophagus, a condition that often progresses to cancer.

The information covers some of the key stages in the care pathway for these patients.  First, it is recommended that patients have their diagnosis of high grade dysplasia confirmed by two pathologists because it is a difficult condition to diagnose.  Second, there are various treatment options for patients with HGD and it is recommended that each patient has their treatment plan discussed at a multi-disciplinary team (MDT) meeting.  Finally, the introduction of endoscopic interventions as an alternative to the surgical removal of the affected part of the oesophagus means that patients now have a less-invasive treatment option.  Consequently, national guidelines recommend active treatment for patients, although surveillance is still an option for patients.

Data sources and time period:

The information was derived from data on patients diagnosed with high grade dysplasia between 1 April 2014 and 31 March 2018.  Data were submitted to the Audit by English NHS trusts.  Information was not available for Welsh Local Health Boards.

Because the number of patients diagnosed at each organisation is small, the information about an NHS trust is based on the patients that were diagnosed within its Cancer Alliance during this period.

 

Management of patients with oesophago-gastric (OG) cancer

This section provides information on the diagnosis and treatment of patients with oesophageal or stomach (gastric) cancer.  The information covers key stages in the pathway from diagnosis to treatment planning.  Information on surgical outcomes is provided in the subsequent section for NHS organisations that undertake curative OG cancer surgery.

Patients with OG cancer are typically diagnosed after a patient is referred by their general practitioner.  However, some patients will be diagnosed after an emergency admission at hospital.  This is less desirable because these patients are often diagnosed with more advanced cancer than those referred by their GP.

After diagnosis, patients undergo a series of investigations to determine the size of the tumour and whether any cancer cells have spread to other parts of their body, a process known as staging.  Guidelines recommend that all patients have a CT scan as part of this process.

When staging is complete, each patient has their treatment plan discussed at a multi-disciplinary team (MDT) meeting.  If the cancer has not spread to other parts of the body, a patient may be suitable for curative treatment.  If this is not possible, patients who are sufficiently fit may have chemotherapy or radiotherapy to manage their symptoms.

Data sources and time period:

The information was derived from data on patients diagnosed with OG cancer between 1 April 2016 and 31 March 2018.  The information about an NHS organisation is based on all patients that were diagnosed at it.

Data were submitted to the Audit for English NHS trusts and Welsh Local Health Boards.

 

Outcomes for OG cancer patients who have curative surgery  

This section provides information on various outcomes after patients with OG cancer have curative surgery.  The information is available for English NHS trusts and Welsh health boards.

Surgeon level figures for English NHS trusts can be found at augis.org.  Welsh Health boards do not participate in the clinical outcome programme.

Time period:

The information on surgical outcomes was derived from data on patients diagnosed between 1 April 2015 and 31 March 2018.  The information about an NHS organisation is based on all patients that had surgery there.  The patient might have been diagnosed at another NHS hospital.

The information is available for English NHS trusts or Welsh health boards.

Things to consider about the data source:

To ensure accuracy, the Audit used information about patients’ date of death as reported by the NHS organisations as well as from the National Death Register.  The Audit also sent the outcome information to NHS trusts and individual surgeons prior to publication for verification.

Considerable care should be taken in making comparisons between NHS organisations on the basis of the figures reported here, as outcomes may vary due to random variation, case-mix or data quality. Every effort has been made to ensure the accuracy of the information reported.  The NOGCA does not accept any liability arising from errors or omissions, or the use of, or reliance on, the information contained in this website and reserve the right to change the information and descriptions when required.

In looking at this information, it is important to remember that the outcomes of NHS trusts and surgeons may vary because of patient characteristics and the influence of random variation.  We recommend that patients discuss the likely outcomes of their treatment with their surgeon before an operation, so that they can understand the expected outcomes given their own circumstances.

Interpretation of results:

When the number of operations is low, rates are often unreliable due to the influence of random events.  Moreover, the observed rates cannot represent a low underlying risk precisely.  For example, although the underlying risk of an operation may be 2%, surgeons who perform just 10 operations could equally have observed mortality rates of 0%, 10%, etc.

Because it becomes difficult to estimate outcomes accurately from a small number of operations, we do not report outcomes for NHS organisations who performed fewer than ten procedures in the reporting period.

 

Volume of surgery

Why is this important?

The volume of care is the number of oesophago-gastric cancer procedures conducted by a surgeon or NHS organisation.

A low volume does not mean that a surgeon is inexperienced in the procedure as he or she might have performed a lot of operations in the past.  A surgeon will also be performing other procedures (not for cancer) on the stomach and its connecting organs.

In general, as the volume of procedures increases, the mortality rates get closer to the national average. With higher volumes, there is more certainty about the outcomes of the surgeon or trust because the results will be less affected by chance.

 

Length of hospital stay

Why is this important?

An oesophagectomy or gastrectomy is a major procedure that involves certain risks. Patients need to stay in hospital after surgery to assess the immediate outcomes of the procedure and ensure recovery. We provide information on the median length of stay, to inform patients about what they can expect when admitted to the hospital for an operation.

For patients diagnosed between 1 April 2015 and 31 March 2018, the median length of stay for patients undergoing surgery for oesophageal or stomach cancer was 11 days.

Length of stay depends on the patient’s general level of fitness and social situation, as well as whether complications occur after the surgery, and to some extent, on the hospital policy for the post-treatment period. This indicator does not allow any definitive judgement on the performance of the surgery, but provides important information for patients and their family to inform them about what is to be expected after the procedure.

 

30 day and 90 day postoperative mortality following oesophagectomy or gastrectomy (risk-adjusted)

Why are these indicators important?

The 30-day and 90-day postoperative mortality rates provide information about the risk of the surgery.  30-day mortality rates focus on the immediate period after surgery, a period in which complications may occur.  90-day postoperative mortality covers an extended period of recovery after surgery and reflects not just the quality of the surgical intervention but the contribution of the multidisciplinary teams at the specialist cancer centres.  Both outcomes are highly dependent on the patient’s fitness, but also on the surgical skill and the intensive care support available at the specialist cancer centres.

Interpretation of results:

For patients diagnosed between 1 April 2015 and 31 March 2018, the average 30-day and 90-day postoperative mortality rates were 1.9% and 3.4%, respectively.  For individual organisations, these percentages may vary simply because of chance. For example, if 50 patients had their operation at an organisation, we would expect (on average) one patient death within 30 days of surgery. However, chance events can produce three or four fold variation in mortality rates without these rates indicating that a specialist cancer centre is performing better or worse than expected.

Because the variation produced by random events increases as outcome figures are calculated from smaller samples, the outcomes should always be interpreted in combination with the number of procedures performed at an organisation.

Some surgeons may operate on patients who are on average sicker than the patients of other surgeons, for whom surgery may be higher risk.  Therefore, when the data are analysed, the process takes into account differences in the characteristics of patients seen at different NHS organisations. The postoperative mortality figures have been adjusted for various patient attributes such as age, site of tumour, how advanced the cancer is, and whether patients suffer from other conditions.  However, risk-adjustment is never perfect and higher mortality rates may still partly reflect that an organisation treats sicker patients on average.

 

Unadjusted proportion of patients with adequate lymph nodes examined for oesophagectomy and gastrectomy

Why is this indicator important?

Lymph nodes are removed from the patient during surgery to assess the stage of the cancer. The lymph nodes are examined to see if they contain any malignant cells, and the results of this help doctors assess whether patients require further treatment after surgery. The adequate number of lymph nodes examined has been defined as 15 for both oesophagectomy and gastrectomy by the Association of Upper Gastrointestinal Surgeons (AUGIS): www.augis.org/wp-content/uploads/2016/06/Provision-of-Services-June-2016.pdf.

Interpretation of results:

For patients diagnosed between 1 April 2015 and 31 March 2018, the national average for the unadjusted proportion of patients with adequate lymph nodes examined is 84.4%.

It is important to note that there are various factors that surgeons consider when deciding how many lymph nodes to remove for examination, including patient characteristics, the type of treatment they had before surgery, and the type of operation.

The results should be interpreted cautiously because we are trying to understand the differences in surgical practices in England that may contribute towards the variation in these results.  We do not recommend benchmarking NHS organisations against the national average at this stage, and our aim is to improve the standardisation in surgical practices and pathological interpretation.

 

Proportion of patients with positive longitudinal margins for oesophagectomy (risk adjusted)

Proportion of patients with positive longitudinal margins for gastrectomy (risk adjusted)

Why are these indicators important?

A positive longitudinal margin after oesophageal or stomach cancer surgery indicates that the patient could require further treatment and monitoring, as the tumour may not have been removed completely. The indicator is a recognised measure of surgical effectiveness and it is important for NHS organisations regularly review the proportion of patients with positive longitudinal margins.

Interpretation of results:

For patients diagnosed between 1 April 2015 and 31 March 2018, the national average for the proportion of patients with positive longitudinal margins after oesophagectomy was 3.8% and after gastrectomy was 7.2%.

It is important to note that the proportion of patients with positive longitudinal margins for both operations may vary due to patient characteristics, the type of treatment they had before surgery and the type of operation. We have adjusted the published figures for the factors that we know influence the risk of a positive margin being found, but there may be other factors that differ from trust to trust which we have not captured in the data.

The results should be interpreted cautiously because we are trying to understand the differences in surgical practices in England that may contribute towards the variation in these results.

 

Proportion of patients with positive circumferential margins for oesophagectomy (risk adjusted)

Why is this indicator important?

A positive circumferential margin after oesophageal cancer surgery indicates that the patient could require further treatment and monitoring, as it was not possible for the surgery to completely remove the tumour. The indicator is a recognised measure of surgical effectiveness and it is important for NHS organisations regularly review the proportion of patients with positive circumferential margins.

Interpretation of results:

For patients diagnosed between 1 April 2015 and 31 March 2018, the national average for the proportion of patients with positive circumferential margins for oesophagectomy was 25.1%.

It is important to note that the proportion of patients with positive circumferential margins for oesophagectomy may vary due to patient characteristics, the type of treatment they had before surgery and the type of operation. We have adjusted the published figures for the factors that we know influence the risk of a positive margin being found, but there may be other factors that differ from trust to trust which we have not captured in the data.

The results should be interpreted cautiously because at this initial stage we are trying to understand the differences in surgical practices in England that may contribute towards the variation in these results.  Hence, we have not benchmarked the NHS organisations against the national average as our aim is to drive standardisation in surgical practices and pathological interpretation, so that eventually this indicator can be used for benchmarking.

 

Interpretation of funnel plots

Trust 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 organisations should not be ranked, as this would be misleading.

The variation in postoperative mortality rates is displayed using a graph known as a funnel plot. The benefit of this approach is that it shows whether the outcomes for individual NHS trusts 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 plots, each dot represents an English NHS trust / Welsh health board and they are centred on the national average. Example:  The national average for 30-day and 90-day postoperative mortality is approximately 1.9% and 3.4%, respectively.  The vertical axis indicates the outcome, with dots higher up the axis showing NHS trusts with a higher mortality rate. The horizontal axis shows surgical activity with dots further to the right showing the NHS organisations which perform more operations.

Funnel plots include control limits to define the range within which we would expect NHS trusts outcomes to lie.  Following convention, we use 99.8% control limits.  It is unlikely for an NHS organisation to fall beyond these limits solely because of random variation (a 1 in 500 chance).  If the outcome figures for an NHS trust 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