SNAP-2 (EpiCCS): Project Outline


SNAP-2: EpiCCS will be the second Sprint National Anaesthesia Project, managed by the National Institute of Academic Anaesthesia Health Services Research Centre (NIAA-HSRC) in conjunction with the UCL/UCLH Surgical Outcomes Research Centre (SOuRCe).

SNAP-2: EpiCCS will describe the epidemiology of perioperative risk and outcome, and critical care referral and admission after inpatient surgery in the UK. A secondary aim is to estimate the clinical effectiveness of planned postoperative critical care admission as an intervention to reduce postoperative morbidity.

Background and Rationale

SNAP-2: EpiCCS aims to provide a 'snapshot' of clinical activity in hospitals throughout the UK over a one week period commencing Tuesday 21st March 2017. The exact dates will be publicised in due course.

Surgical morbidity and mortality is a well-described public health issue. An estimated 313 million operations take place world-wide each year. Morbidity or complications after surgery occur up to ten times more frequently than short-term mortality and are associated with reduced long-term survival, even after accounting for known preoperative patient-related risk factors. Planned postoperative critical care admission is recommended for the "high risk surgical patient"; cohort studies reveal that despite this, the majority of patients undergoing non-cardiac, non-neurological surgery who die before hospital discharge do not have planned critical care admission after surgery.

SNAP-2: EpiCCS will explore the referral patterns and resource limitations which may be responsible for patients not being admitted to critical care, despite being high risk according to national guidelines. In particular, we will explore the areas of Quality and accuracy of risk stratification, Critical Care bed capacity, and Clinical uncertainty that critical care admission would be of benefit.

Study design

EpiCCS will be a prospective observational cohort study with two principle components:

  • Main EPICCS patient study
    All patients undergoing inpatient surgery (elective or emergency) during the study week will be enrolled onto the main EPICCS study.
  • Clinicians sub-study
    All anaesthetists and surgeons who undertake perioperative care for inpatient surgery during the study period will be invited to participate. If they decline, they will be asked to provide the reason why. If they agree and complete the questionnaire, this will be taken as evidence of implied consent.

Additionally, an organisational questionnaire for each hospital will be completed to describe structure and process in those institutions, and critical care unit occupancy at regular time-intervals throughout the one-week data collection period.

Ethical considerations

The two part nature of SNAP-2: EpiCCS study will require two types of participant, with differing approaches to consent for each type:

  • Main EpiCCS patient study: Section 251 exemption to be sought
    To be able to collect patient data without consent, we have been granted a Section 251 exemption. The reason for a non-consenting approach is an attempt to avoid sampling bias. It is likely that patients who are of higher perioperative risk will be unable or unwilling to provide consent - we have data from SNAP-1 to support this assertion.
  • Clinicians' perceptions sub-study: implied consent approach
    We propose an implied consent approach, with completion of the questionnaire as evidence of consent. Every perioperative anaesthetist and surgeon during the study week will be asked to complete a questionnaire which explores their approach to risk stratification and postoperative care. Given that there are national guidelines regarding these questions, we are keen to provide reassurance to perioperative anaesthetists and surgeons that their responses will be used in confidence, without risk of litigation or reprisal. If anaesthetists or surgeons choose not to answer the questionnaire, then they will be asked to provide a reason why, for the purposes of analysis.

Inclusion criteria

Adult ( >=18 years ) patients undergoing surgery or other interventions who are expected to require overnight stay in hospital which require the support of an anaesthetist. These would include all procedures taking place in an operating theatre, radiology suite, endoscopy suite or catheter laboratory for which inpatient (overnight) stay is planned, including both planned and emergency/urgent surgery of all types, Caesarean section, surgery for complications of childbirth, endoscopy and interventional radiology.

Exclusion criteria

Patients who indicate they do not want to participate in the study; Ambulatory surgery; children (<18 years); non-surgical obstetrics; ASA-PS grade VI; non-interventional diagnostic imaging (e.g. CT or MRI scanning without interventions); emergency department or critical care interventions requiring anaesthesia or sedation but no interventional procedure.

How will SNAP-2: EpiCCS work in my hospital?

The intention is that data collection at each site will be managed predominantly by anaesthetic trainees, with support from consultants and research nurses, under the supervision of a Local Principal Investigator who may be the Quality Audit and Research Coordinator (QuARC), the departmental audit lead, the clinical director, or another nominated representative. The study has now been adopted onto the NIHR CRN Portfolio (CPMS ID: 31913). This should mean that you can access support for recruiting to the study from NIHR funded Clinical Research Network nurses. Your local NIHR Clinical Research Network lead, or your local R&D office should be able to provide you with support and information. All participants (including clinicians taking part in the survey study) will count towards accruals. Patients will not be provided written consent for the 7-day study, but are offered the option to opt-out, via distribution of patient information sheets, and are considered as having been informed and therefore count towards accruals.

How do I get involved?

At the moment we are still in set-up for SNAP-2. We have made contact with SNAP-1 local lead investigators to ask them to register their Trust's interest in the study. If you are a trainee or consultant who would like to be involved, please stay in touch via our Twitter feed @SNAP2EPICCS.


  • To collect data on all patients undergoing inpatient surgery for one week in UK NHS hospitals.
  • To measure and analyse patient-level estimates of perioperative risk using previously validated risk prediction tools to determine their accuracy (discrimination and calibration) in a comprehensive national sample.
  • To use three different analytic techniques (regression, instrumental variable and propensity score matched analyses) to measure the relationship between patient risk factors, postoperative critical care admission and patient outcomes (morbidity mortality and quality of recovery).
  • To survey anaesthetists and surgeons on their attitudes and behaviours regarding risk prediction and postoperative critical care admission.

Further information

  • The latest information on SNAP-2 can be found on the SNAP website.
  • Read our privacy policy here:  SNAP-2 Privacy Notice (128 KB)
  • Follow @SNAP2EPICCS on Twitter.
  • Email:
  • SNAP-2 EpiCCS is generously supported by the Royal College of Anaesthetists and the Association of Anaesthetists of Great Britain and Ireland.