NNAP Neurosurgical National Audit Programme













Q1. What is the aim of the Neurosurgical National Audit Programme (NNAP)?

The Society of British Neurological Surgeons (SBNS) established the NNAP to promote improvements in the quality of neurosurgical services and patient care by providing neurosurgical units in NHS England with a comprehensive audit programme that reflects the full range of elective and emergency neurosurgical activity.

Q2. Why is this data being published?

There is evidence from other national audits that the publication of activity and audit data, when carefully analysed and interpreted, leads to improvements in patient outcomes. The SBNS supports the publication of outcome data that will promote the understanding of the range and complexity of neurosurgical services and the steps being taken to improve those services.

Q3. What is HES data and how has it been collected?

The unit and surgeon level outcome data presented in these reports is based on the analysis of the Hospital Episode Statistics (HES) service data which has been linked to Civil Registry mortality data. Hospitals record information on every patient admission using codes for diseases and conditions (ICD10) and codes that reflect operations and procedures (OPCS4). NNAP obtains the data from NHS Digital (NHSD) following a formal process which ensures that the correct information governance and data security requirements for processing the data are in place.

Each HES record contains a wide range of information including:

  • Clinical details: diagnoses and operations.
  • Patient details: age, gender and ethnicity.
  • Administrative details: waiting times, dates and methods of admission and discharge arrangements.
  • Geographical details: domicile and treatment unit.

The Neurosurgical National Audit Programme has used this detailed dataset to present activity and mortality data for all neurosurgical units and all consultant neurosurgeons practising in the NHS in England.

Q4. What procedures are included and why?

The outcomes presented are based on all elective (planned) operations undertaken by consultant neurosurgeons in England. This is the first national audit to report on all the activity of a surgeon, rather than selected index procedures. There are currently thirty neurosurgical units within England, five of which are paediatric only units. Only procedures recorded in these units with a consultant specialty of 'Neurosurgery' are included in the data.

Q5. What is the difference between elective and non-elective surgery?

An elective surgical procedure is usually a planned procedure that has been booked in advance and has involved outpatient consultations and investigations. A non-elective surgical procedure usually follows an emergency or urgent admission to hospital often through an emergency department or by direct transfer from a district general hospital to the neurosurgical unit.

Q6. Do all neurosurgeons perform all procedures?

All neurosurgeons perform a core set of emergency neurosurgical procedures. Most neurosurgeons will also specialise in one or several subspecialist areas such as: spinal, neurovascular, functional and skull base surgery. Paediatric neurosurgeons specialise in neurosurgical operations on children.

Q7. What is risk adjustment?

The NNAP presents risk adjusted (or case-mix adjusted) mortality data to take account of the fact that neurosurgery involves a wide range of operations of varying duration, complexity and risk and that some patients may be at higher risk because of their age or underlying problems with their health. Risk adjustment allows a fairer comparison between individual hospitals; but it is important to remember that risk-adjustment does not account for all factors influencing a patient's outcome. It should also be noted that modern neurosurgery is a complex process that involves teams of neuro-anaesthetists, interventional radiologists, other specialist surgeons and intensive care specialists all of whom contribute to the final outcome of the patient. The indicator on which the analysis is based is death within 30 days of a procedures for adult, elective procedures.

Q8. Why doesn't NNAP consider 30 data mortality outcomes for individual surgeons?

The data provided by trusts to HES is of varying quality and this applies to the clinical attribution of patient episodes, i.e. assigning an episode of care to the correct consultant. Factors other than data quality also make consultant level analysis difficult, e.g. different admission procedures in different trusts. Experience has shown that the data is not of sufficient quality to publish accurate consultant-level mortality outcomes.

Q9. What does the consultant activity pie chart represent?

A surgeon could have up to four pie charts displayed, dependent upon their practice:

  • Adult elective.
  • Adult non-elective.
  • Paediatric elective.
  • Paediatric non-elective.

The number of procedures shown in the pie charts (and the accompanying tables) are based on the latest 12 months and the latest 36 months of a consultant's practice. The reporting periods are based on a financial year (FY), 1 April to 31 March.

The pie chart separates procedures into 'Spinal', 'Cranial', and 'Other': spinal procedures include operations performed on the discs and bones of the spine; cranial procedures include all operations that were performed on the brain and surrounding structures of the head; other procedures include some elective diagnostic procedures, peripheral nerve surgery and specialist procedures such as radiosurgery.

Q10. What does the Unit activity pie chart show?

The unit activity pie charts are the same as those for surgeons but include all the activity for all consultants with a neurosurgery specialty within the unit. Like the surgeon pie charts, they are separated into cranial, spinal, and 'other' procedures and include the latest 12 months and latest 36 month totals.

Q11. What does the Unit funnel plot show?

The unit funnel plot displays the risk adjusted standard mortality ratio (SMR), based on mortality within thirty days of a procedure, for the named unit. The magenta plot displayed on the graph represents the individual unit and is aligned with the expected number of deaths on the x-axis (horizontal axis) and the risk-adjusted SMR on the y-axis (vertical axis). The grey, straight line represents the national average mortality ratio and the coloured lines represent control limits at 99.8% and 95%. The data would indicate 'outlier' performance where their plot lies above the upper 99.% control limit (blue line). Any pot below this line indicates that a unit's overall mortality outcomes are within an expected range. A unit's data can indicate outlier performance even if there are no outlier surgeons.

There are currently no funnel plots created for paediatric units as the analysis is based on adult, elective procedures only. The SBNS will be working with specialist paediatric units and surgeons to agree a suitable risk adjustment method for paediatric surgery.

Q12. I am a surgeon - how do I view and update my data?

When the latest data is available it is automatically uploaded onto the website. An individual surgeon's data is also uploaded into their individual profile. Included in that information are mortality events attributed to the surgeon in the latest 12 month reporting period. It should be noted that this data is for information only - it is not included in any mortality analyses and is not published. Surgeons are also able to update their personal profile information that is displayed on the website. To do this, an NNAP user account is required. See the document 'NNAP Account Set Up' in the 'Policies and Publications' section of the NNAP website.

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