Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

EP.FRI.450 Gastrograffin use in Non-Adhesional Small bowel Obstruction

Aims

Use of Gastrograffin (GG) radio-opaque contrast has been documented in the management of adhesional small bowel obstruction. It is not widely used in other causes of small bowel obstruction. The aim of this study was to assess the effectiveness of GG use in non-adhesive small bowel obstructions. 

Methods

A retrospective review of patients who had GG administered following CT confirmed small bowel obstruction (SBO) over 2-year period was conducted. Demographics, cause of SBO and outcomes were recorded. The primary outcome was resolution of SBO with GG.  

Results

80 patients received GG for management of radiologically confirmed small bowel obstruction. The mean age was 62.7 years +/- 14.64 (SD) and M:F ratio was 1:1. The causes of small bowel obstruction included adhesions (n = 37, 46%), hernias (n = 17, 21%), progression of known cancer (n = 3, 4%). 18% (n = 15) had no clear cause of SBO on CT. In the adhesion group, GG resolved SBO in n = 27 (73%) of patients. In the hernia group 7 (41%) were incisional hernias and 7 (41%) were parastomal hernias. GG was given to both groups and the obstruction resolved in n = 6 (86%) and n = 4 (57%) of cases respectively. 

Conclusions

This study shows the effective use of GG in hernia related SBO where there is no absolute indication for surgery. GG might be suitable for incisional and parastomal hernias as a bridge to resolving acute SBO allowing a delayed repair with complex techniques.

113 Ischaemic Bowel in The North of England: Trends in Management Approach And Patient Outcomes

Aim

Bowel ischaemia is the third most common indication for emergency laparotomy in the UK and is associated with high rates of postoperative morbidity and mortality. This study describes changes in incidence, patient characteristics, management approach and outcomes for patients with bowel ischaemia over a fifteen-year period

Method

Data for patients admitted as an emergency, with a diagnosis of bowel ischaemia, to NHS hospitals in the North of England between 2002 and 2016 were collected. This included patient demographics and co-morbidities, operations performed and outcomes. The primary outcome of interest was in-hospital death within 30 days of admission for non-operatively managed patients and 30-day post-operative mortality for those who underwent an operative intervention.

Results

The incidence of bowel ischaemia has increased as a proportion of emergency general surgery admissions by 68% over fifteen years. More patients are undergoing computerised tomography (CT) imaging has (44.0% vs. 70.3%, p<0.001) and more operations are being performed within 48 hours of admission (p<0.001). The number of patients being managed operatively has fallen from 56.7% to 38.7%. Decreased 30-day mortality rates were observed for both operatively (37.5% to 26.7%, p<0.001) and non-operatively (45.7% to 26.8%, p<0.001) managed patients. Mean length of hospital stay has remained relatively unchanged over time.

Conclusions

Ischaemic bowel is becoming increasingly common. Increased usage of CT imaging has likely resulted in decreased rates of operative management due to its ability to accurately characterise intra-abdominal pathology. Improved mortality rates were observed for both operative and non-operative management strategies.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Evaluating outcomes following emergency laparotomy in the North of England and the impact of the National Emergency Laparotomy Audit - A retrospective cohort study

BACKGROUND

Emergency laparotomy is associated with high morbidity and mortality. Current trends suggest improvements have been made in recent years, with increased survival and shorter lengths of stay in hospital. The National Emergency Laparotomy Audit (NELA) has evaluated participating hospitals in England and Wales and their individual outcomes since 2013. This study aims to establish temporal trends for patients undergoing emergency laparotomy and evaluate the influence of NELA.

METHODS

Data for emergency laparotomies admitted to NHS hospitals in the Northern Deanery between 2001 and 2016 were collected, including demographics, co-morbidities, diagnoses, operations undertaken and outcomes. The primary outcome of interest was in-hospital death within 30 days of admission. Cox-regression analysis was undertaken with adjustment for covariates.

RESULTS

There were 2828 in-hospital deaths from 24,291 laparotomies within 30 days of admission (11.6%). Overall 30-day mortality significantly reduced during the 15-year period studied from 16.3% (2001-04), to 8.1% during 2013-16 (p < 0.001). After multivariate adjustment, laparotomies undertaken in more recent years were associated with a lower mortality risk compared to earlier years (2013-16: HR 0.73, p < 0.001). There was a significant improvement in 30-day postoperative mortality year-on-year during the NELA period (from 9.1 to 7.1%, p = 0.039). However, there was no difference in postoperative mortality for patients who underwent laparotomy during NELA (2013-16) compared with the preceding three years (both 8.1%, p = 0.526).

DISCUSSION

30 day postoperative mortality for emergency laparotomy has improved over the past 15-years, with significantly reduced mortality risk in recent years. However, it is unclear if NELA has yet had a measurable effect on 30-day post-operative mortality.

Evaluating the effects of surgical subspecialisation on patient outcomes following emergency laparotomy: A retrospective cohort study

BACKGROUND

General surgeons have become increasingly subspecialised in their elective practice. Emergency laparotomies, however, are performed by a range of subspecialists who may or may not have an interest in the affected area of gastrointestinal tract. This retrospective cohort study evaluates the impact of surgical subspecialisation on patient outcomes following emergency laparotomy.

METHODS

Data was collected for patients who underwent an emergency abdominal procedure on the gastrointestinal tract in the North of England from 2001 to 2016. This included demographics, co-morbidities, diagnoses and procedures undertaken. Patients were grouped according to consultants' subspecialist interest. The primary outcome of interest was 30-day postoperative mortality.

RESULTS

24,291 emergency laparotomies were performed with an associated 30-day postoperative mortality of 11.7%. Laparotomies undertaken by upper gastrointestinal (UGI) or colorectal surgeons have significantly lower mortality (10.1%) when compared with other subspecialities (13.5%). More specifically, mortality was decreased for UGI (7.9% vs. 12.9%) and colorectal procedures (10.9% vs. 14.2%) when performed by surgeons with a specialist interest in the relevant area of the gastrointestinal tract (both p < 0.001). The utilisation of laparoscopic surgery is higher, in both UGI (21.8% vs. 9.0%) and colorectal procedures (7.2% vs. 3.5%), when the causative pathology is relevant to the surgeon's subspeciality (both p < 0.001).

CONCLUSION

Mortality following emergency laparotomy is improved when performed under the care of gastrointestinal surgeons. Both UGI and colorectal emergency procedures have improved outcomes, with lower mortality and higher rates of laparoscopy, when under the care of a surgeon with a subspecialist interest in the affected area of the gastrointestinal tract.

Protocol for a multicentre, prospective, observational cohort study of variation in practice in perioperative analgesic strategies in elective laparoscopic colorectal surgery: the LapCoGesic Study

INTRODUCTION

Laparoscopic surgery combined with enhanced recovery programmes has become the gold standard in the elective management of colorectal disease. However, there is no consensus with regard to the optimal perioperative analgesic regime in this cohort of patients, with a number of options available, including thoracic epidural spinal analgesia, patient-controlled analgesia, subcutaneous and/or intraperitoneal local anaesthetics, local anaesthetic wound infiltration catheters and transversus abdominis plane blocks. This study aims to explore any differences in analgesic strategies employed across the North East of England and to assess whether any variation in practice has an impact on clinical outcomes.

METHODS AND ANALYSIS

All North East Colorectal units will be recruited for participation by the Northern Surgical Trainees Research Association (NoSTRA). Data will be collected over a consecutive 2-month period. Outcome measures will include postoperative pain score, postoperative opioid analgesic use and side effects, length of stay, 30-day complication rates, 30-day reoperative rates and 30-day readmission rates.

ETHICS AND DISSEMINATION

Ethical approval for this study has been granted by the National Research Ethics Service. The protocol will be disseminated through NoSTRA. Individual unit data will be presented at local meetings. Overall collective data will be published in peer-reviewed journals and presented at relevant surgical meetings.

Retrospective analysis of 30-day mortality for emergency general surgery admissions evaluating the weekend effect

Background

The weekend effect describes excess mortality associated with hospital admission on Saturday or Sunday. This study assessed whether a weekend effect exists for patients admitted for emergency general surgery.

Methods

Data for emergency general surgical admissions to National Health Service hospitals in the Northern Deanery in England between 2000 and 2014 were collected, including demographics, co-morbidities, diagnoses, operations undertaken and outcomes. The primary outcome of interest was in-hospital death within 30 days of admission. Cox regression analysis was undertaken with adjustment for co-variables.

Results

There were 12 100 in-hospital deaths within 30 days of admission (3·3 per cent). The overall 30-day mortality rate reduced significantly during the 15-year interval studied, from 5·4 per cent (2000–2004) to 4·0 per cent (2005–2009) and 2·9 per cent during 2010–2014 (P &lt; 0·001). There was no significant mortality difference for patients admitted at the weekend in adjusted Cox models (hazard ratio (HR) 1·00 for Saturday and 0·90 for Sunday, versus Wednesday). There was a significantly higher mortality for operations undertaken at the weekend (HR 1·15 for Saturday and 1·40 for Sunday; P = 0·021 and P &lt; 0·001 respectively). The significantly increased mortality that was evident for emergency surgery at the weekend compared with weekdays in 2000–2004 (HR 1·46 for Saturday and 1·55 for Sunday; both P &lt; 0·001); had reduced by 2010–2014, when the adjusted mortality risk was not significant (HR 1·18 for Saturday and 1·12 for Sunday).

Conclusion

During the past 15 years there has been a weekend effect in patients undergoing emergency general surgery based on day of operation, but not day of admission. Overall mortality for emergency general surgery has improved significantly, and in the past 5 years the increased mortality risk of weekend surgery has reduced.

Characterization of comorbid factors in hip fracture related in-hospital mortality

It is important to delineate factors which influence in-hospital mortality rates following a hip fracture. The current study aimed to identify the nature and frequency of comorbidities prevalent in this patient cohort. A retrospective chart review of cases of in-patient mortality following admission for a hip fracture was performed. These cases (n=127) were characterized for comorbidities, complications, medical status indicators, and other contributory factors. Cardiovascular 104 (81.9%), respiratory 66 (52.0%), genitourinary 41 (32.3%), psychiatric 41 (32.3%), vascular 40 (31.5%), and gastrointestinal 40 (31.5%), are the physiological systems, most commonly associated with comorbidity amongst hip fracture patients who succumb to in-hospital mortality. Renal failure, pneumonia, sepsis, myocardial infarction, congestive cardiac failure (CCF), respiratory failure, and Clostridium difficile infection are conditions which are associated with postoperative complications leading to in-patient mortality. Analysis of medical status indicators illustrated an inverse correlation between ASA scores and postoperative survival time, in this cohort-of hip fracture patients (R2 = 0.9485).

Screening for subclinical Cushing's syndrome in type 2 diabetes mellitus: low false-positive rates with nocturnal salivary cortisol

The diagnosis of subclinical Cushing's syndrome (SCS) is important, but its relative rarity amongst patients with common metabolic disorders requires a simple test with a low false-positive rate. Using nocturnal salivary cortisol (NSC), which we first validated in patients with suspected and proven Cushing's syndrome, we screened 106 overweight patients with type 2 diabetes mellitus, a group at high risk of SCS and nontumoral hypothalamic-pituitary-adrenal axis perturbations. Our hypothesis was that a lower false-positive rate with NSC was likely, compared with that reported with the dexamethasone suppression test (DST) (10-20%), currently the foundation of diagnosis of SCS. No participant had clinically apparent Cushing's syndrome. Three participants had an elevated NSC but further testing excluded SCS. In this study, NSC had a lower false-positive rate (3%) than previously reported for the DST. Given the reported excellent performance of NSC in detection of hypercortisolism, the low false-positive rate in SCS suggests NSC may be superior to the DST for SCS screening. The NSC and DST should be compared directly in metabolic disorder patients; although our data suggest the patient group will need to be substantially larger to definitively determine the optimal screening test.