A systematic review and meta-analysis of the clinimetric properties of the core outcome measurement instruments for clinical effectiveness trials of nutritional and metabolic interventions in critical illness (CONCISE).

BACKGROUND: CONCISE is an internationally agreed minimum set of outcomes for use in nutritional and metabolic clinical research in critically ill adults. Clinicians and researchers need to be aware of the clinimetric properties of these instruments and understand any limitations to ensure valid and reliable research. This systematic review and meta-analysis were undertaken to evaluate the clinimetric properties of the measurement instruments identified in CONCISE. METHODS: Four electronic databases were searched from inception to December 2022 (MEDLINE via Ovid, EMBASE via Ovid, CINAHL via Healthcare Databases Advanced Search, CENTRAL via Cochrane). Studies were included if they examined at least one clinimetric property of a CONCISE measurement instrument or recognised variation in adults ≥ 18 years with critical illness or recovering from critical illness in any language. The COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist for systematic reviews of Patient-Reported Outcome Measures was used. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses were used in line with COSMIN guidance. The COSMIN checklist was used to evaluate the risk of bias and the quality of clinimetric properties. Overall certainty of the evidence was rated using a modified Grading of Recommendations, Assessment, Development and Evaluation approach. Narrative synthesis was performed and where possible, meta-analysis was conducted. RESULTS: A total of 4316 studies were screened. Forty-seven were included in the review, reporting data for 12308 participants. The Short Form-36 Questionnaire (Physical Component Score and Physical Functioning), sit-to-stand test, 6-m walk test and Barthel Index had the strongest clinimetric properties and certainty of evidence. The Short Physical Performance Battery, Katz Index and handgrip strength had less favourable results. There was limited data for Lawson Instrumental Activities of Daily Living and the Global Leadership Initiative on Malnutrition criteria. The risk of bias ranged from inadequate to very good. The certainty of the evidence ranged from very low to high. CONCLUSIONS: Variable evidence exists to support the clinimetric properties of the CONCISE measurement instruments. We suggest using this review alongside CONCISE to guide outcome selection for future trials of nutrition and metabolic interventions in critical illness. TRIAL REGISTRATION: PROSPERO (CRD42023438187). Registered 21/06/2023.

Enhanced peri-operative care to improve outcomes for high-risk surgical patients in Brazil: a single-centre before-and-after cohort study.

Mortality and morbidity for high-risk surgical patients are often high, especially in low-resource settings. Enhanced peri-operative care has the potential to reduce preventable deaths but must be designed to meet local needs. This before-and-after cohort study aimed to assess the effectiveness of a postoperative 48-hour enhanced care pathway for high-risk surgical patients ('high-risk surgical bundle') who did not meet the criteria for elective admission to intensive care. The pathway comprised of six elements: risk identification and communication; adoption of a high-risk post-anaesthesia care unit discharge checklist; prompt nursing admission to ward; intensification of vital signs monitoring; troponin measurement; and prompt access to medical support if required. The primary outcome was in-hospital mortality. Data describing 1189 patients from two groups, before and after implementation of the pathway, were compared. The usual care group comprised a retrospective cohort of high-risk surgical patients between September 2015 and December 2016. The intervention group prospectively included high-risk surgical patients from February 2019 to March 2020. Unadjusted mortality rate was 10.5% (78/746) for the usual care and 6.3% (28/443) for the intervention group. After adjustment, the intervention effect remained significant (RR 0.46 (95%CI 0.30-0.72). The high-risk surgical bundle group received more rapid response team calls (24% vs. 12.6%; RR 0.63 [95%CI 0.49-0.80]) and surgical re-interventions (18.9 vs. 7.5%; RR 0.41 [95%CI 0.30-0.59]). These data suggest that a clinical pathway based on enhanced surveillance for high-risk surgical patients in a resource-constrained setting could reduce in-hospital mortality.

Postoperative infection and mortality following elective surgery in the International Surgical Outcomes Study (ISOS).

BACKGROUND: Postoperative infection is one of the most frequent and important complications after surgery. The epidemiology of infection following elective surgery remains poorly described. METHODS: This was a prospective analysis of the International Surgical Outcomes Study (ISOS) describing infection by 30 days after elective surgery. Associations between postoperative infection (primary outcome) and baseline demographic, surgical, and anaesthetic risk factors were assessed. Analyses were carried out using logistic and linear regression models. Secondary outcomes were 30-day mortality and duration of hospital stay. Treatments received by patients after different types of infection were evaluated. RESULTS: Some 44 814 patients were included in the analysis, with a total of 4032 infections occurring in 2927 patients (6.5 per cent). Overall, 206 patients died, of whom 99 of 2927 (3.4 per cent) had infection. Some 737 of 4032 infections (18.3 per cent) were severe; the most frequent types were superficial surgical-site infection (1320, 32.7 per cent), pneumonia (708, 17.6 per cent), and urinary tract infection (681, 16.9 per cent). Excluding missing data, antimicrobials were used in 2126 of 2749 infections (77.3 per cent), and 522 of 2164 patients (24.1 per cent) required admission to critical care. Factors associated with an increased incidence of infection in adjusted analyses were: age, male sex, ASA grade, co-morbid disease, preoperative anaemia, anaesthetic technique, surgical category, surgical severity, and cancer surgery. Infection significantly increased the risk of death (odds ratio 4.68, 95 per cent c.i. 3.39 to 6.47; P < 0.001), and duration of hospital stay by on average 6.45 (6.23 to 6.66) days (P < 0.001). CONCLUSION: Infection is a common complication after elective surgery. Recognition of modifiable risk factors will help inform appropriate prevention strategies.

Resource requirements for reintroducing elective surgery during the COVID-19 pandemic: modelling study.

BACKGROUND: The COVID-19 response required the cancellation of all but the most urgent surgical procedures. The number of cancelled surgical procedures owing to Covid-19, and the reintroduction of surgical acivirt, was modelled. METHODS: This was a modelling study using Hospital Episode Statistics data (2014-2019). Surgical procedures were grouped into four urgency classes. Expected numbers of surgical procedures performed between 1 March 2020 and 28 February 2021 were modelled. Procedure deficit was estimated using conservative assumptions and the gradual reintroduction of elective surgery from the 1 June 2020. Costs were calculated using NHS reference costs and are reported as millions or billions of euros. Estimates are reported with 95 per cent confidence intervals. RESULTS: A total of 4 547 534 (95 per cent c.i. 3 318 195 to 6 250 771) patients with a pooled mean age of 53.5 years were expected to undergo surgery between 1 March 2020 and 28 February 2021. By 31 May 2020, 749 247 (513 564 to 1 077 448) surgical procedures had been cancelled. Assuming that elective surgery is reintroduced gradually, 2 328 193 (1 483 834 - 3 450 043) patients will be awaiting surgery by 28 February 2021. The cost of delayed procedures is €5.3 (3.1 to 8.0) billion. Safe delivery of surgery during the pandemic will require substantial extra resources costing €526.8 (449.3 to 633.9) million. CONCLUSION: As a consequence of the Covid-19 pandemic, provision of elective surgery will be delayed and associated with increased healthcare costs.

Mortality after surgery with SARS-CoV-2 infection in England: a population-wide epidemiological study.

BACKGROUND: The COVID-19 pandemic has heavily impacted elective and emergency surgery around the world. We aimed to confirm the incidence of perioperative severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and associated mortality after surgery. METHODS: Analysis of routine electronic health record data from NHS hospitals in England. We extracted data from Hospital Episode Statistics in England describing adult patients undergoing surgery between January 1, 2020 and February 28, 2021. The exposure was SARS-CoV-2 infection defined by International Classification of Diseases (ICD)-10 codes. The primary outcome measure was 90 day in-hospital mortality. Data were analysed using multivariable logistic regression adjusted for age, sex, Charlson Comorbidity Index, Index of Multiple Deprivation, presence of cancer, surgical procedure type and admission acuity. Results are presented as n (%) and odds ratios (OR) with 95% confidence intervals (CI). RESULTS: We identified 2 666 978 patients undergoing surgery of whom 28 777 (1.1%) had SARS-CoV-2 infection. In total, 26 364 (1.0%) patients died in hospital. SARS-CoV-2 infection was associated with a much greater risk of death (SARS-CoV-2: 6153/28 777 [21.4%] vs no SARS-CoV-2: 20 211/2 638 201 [0.8%]; OR=5.7 [95% CI, 5.5-5.9]; P<0.001). Amongst patients undergoing elective surgery, 2412/1 857 586 (0.1%) had SARS-CoV-2, of whom 172/2412 (7.1%) died, compared with 1414/1 857 586 (0.1%) patients without SARS-CoV-2 (OR=25.8 [95% CI, 21.7-30.9]; P<0.001). Amongst patients undergoing emergency surgery, 22 918/582 292 (3.9%) patients had SARS-CoV-2, of whom 5752/22 918 (25.1%) died, compared with 18 060/559 374 (3.4%) patients without SARS-CoV-2 (OR=5.5 [95% CI, 5.3-5.7]; P<0.001). CONCLUSIONS: The low incidence of SARS-CoV-2 infection in NHS surgical pathways suggests current infection prevention and control policies are highly effective. However, the high mortality amongst patients with SARS-CoV-2 suggests these precautions cannot be safely relaxed.

Development of a Clinical Prediction Model for In-hospital Mortality from the South African Cohort of the African Surgical Outcomes Study.

BACKGROUND: Data on the factors that influence mortality after surgery in South Africa are scarce, and neither these data nor data on risk-adjusted in-hospital mortality after surgery are routinely collected. Predictors related to the context or setting of surgical care delivery may also provide insight into variation in practice. Variation must be addressed when planning for improvement of risk-adjusted outcomes. Our objective was to identify the factors predicting in-hospital mortality after surgery in South Africa from available data. METHODS: A multivariable logistic regression model was developed to identify predictors of 30-day in-hospital mortality in surgical patients in South Africa. Data from the South African contribution to the African Surgical Outcomes Study were used and included 3800 cases from 51 hospitals. A forward stepwise regression technique was then employed to select for possible predictors prior to model specification. Model performance was evaluated by assessing calibration and discrimination. The South African Surgical Outcomes Study cohort was used to validate the model. RESULTS: Variables found to predict 30-day in-hospital mortality were age, American Society of Anesthesiologists Physical Status category, urgent or emergent surgery, major surgery, and gastrointestinal-, head and neck-, thoracic- and neurosurgery. The area under the receiver operating curve or c-statistic was 0.859 (95% confidence interval: 0.827-0.892) for the full model. Calibration, as assessed using a calibration plot, was acceptable. Performance was similar in the validation cohort as compared to the derivation cohort. CONCLUSION: The prediction model did not include factors that can explain how the context of care influences post-operative mortality in South Africa. It does, however, provide a basis for reporting risk-adjusted perioperative mortality rate in the future, and identifies the types of surgery to be prioritised in quality improvement projects at a local or national level.

Functional decline after major elective non-cardiac surgery: a multicentre prospective cohort study.

Self-reported postoperative functional recovery is an important patient-centred outcome that is rarely measured or considered in research and decision-making. We conducted a secondary analysis of the measurement of exercise tolerance before surgery (METS) study for associations of peri-operative variables with functional decline after major non-cardiac surgery. Patients who were at least 40 years old, had or were at risk of, coronary artery disease and who were scheduled for non-cardiac surgery were recruited. Primary outcome was a reduction in mobility, self-care or ability to conduct usual activities (EuroQol 5 dimension) from before surgery to 30 days and 1 year after surgery. A decline in at least one function was reported by 523/1309 (40%) participants at 30 days and 320/1309 (24%) participants at 1 year. Participants who reported higher pre-operative Duke Activity Status indices more often reported functional decline 30 days after surgery and less often reported functional decline 1 year after surgery. The odds ratios (95%CI) of functional decline 30 days and 1 year after surgery with moderate or severe postoperative complications were 1.46 (1.02-2.09), p = 0.037 and 1.44 (0.98-2.13), p = 0.066. Discrimination of participants who reported functional decline 30 days and 1 year after surgery were poor (c-statistic 0.61 and 0.63, respectively). In summary, one quarter of participants reported functional decline up to one postoperative year.

Age of patients undergoing surgery.

BACKGROUND: Advancing age is independently associated with poor postoperative outcomes. The ageing of the general population is a major concern for healthcare providers. Trends in age were studied among patients undergoing surgery in the National Health Service in England. METHODS: Time trend ecological analysis was undertaken of Hospital Episode Statistics and Office for National Statistics data for England from 1999 to 2015. The proportion of patients undergoing surgery in different age groupings, their pooled mean age, and change in age profile over time were calculated. Growth in the surgical population was estimated, with associated costs, to the year 2030 by use of linear regression modelling. RESULTS: Some 68 205 695 surgical patient episodes (31 220 341 men, 45·8 per cent) were identified. The mean duration of hospital stay was 5·3 days. The surgical population was older than the general population of England; this gap increased over time (1999: 47·5 versus 38·3 years; 2015: 54·2 versus 39·7 years). The number of people aged 75 years or more undergoing surgery increased from 544 998 (14·9 per cent of that age group) in 1999 to 1 012 517 (22·9 per cent) in 2015. By 2030, it is estimated that one-fifth of the 75 years and older age category will undergo surgery each year (1·49 (95 per cent c.i. 1·43 to 1·55) million people), at a cost of €3·2 (3·1 to 3·5) billion. CONCLUSION: The population having surgery in England is ageing at a faster rate than the general population. Healthcare policies must adapt to ensure that provision of surgical treatments remains safe and sustainable.

Cardiac vagal dysfunction and myocardial injury after non-cardiac surgery: a planned secondary analysis of the measurement of Exercise Tolerance before surgery study.

BACKGROUND: The aetiology of perioperative myocardial injury is poorly understood and not clearly linked to pre-existing cardiovascular disease. We hypothesised that loss of cardioprotective vagal tone [defined by impaired heart rate recovery ≤12 beats min-1 (HRR ≤12) 1 min after cessation of preoperative cardiopulmonary exercise testing] was associated with perioperative myocardial injury. METHODS: We conducted a pre-defined, secondary analysis of a multi-centre prospective cohort study of preoperative cardiopulmonary exercise testing. Participants were aged ≥40 yr undergoing non-cardiac surgery. The exposure was impaired HRR (HRR≤12). The primary outcome was postoperative myocardial injury, defined by serum troponin concentration within 72 h after surgery. The analysis accounted for established markers of cardiac risk [Revised Cardiac Risk Index (RCRI), N-terminal pro-brain natriuretic peptide (NT pro-BNP)]. RESULTS: A total of 1326 participants were included [mean age (standard deviation), 64 (10) yr], of whom 816 (61.5%) were male. HRR≤12 occurred in 548 patients (41.3%). Myocardial injury was more frequent amongst patients with HRR≤12 [85/548 (15.5%) vs HRR>12: 83/778 (10.7%); odds ratio (OR), 1.50 (1.08-2.08); P=0.016, adjusted for RCRI). HRR declined progressively in patients with increasing numbers of RCRI factors. Patients with ≥3 RCRI factors were more likely to have HRR≤12 [26/36 (72.2%) vs 0 factors: 167/419 (39.9%); OR, 3.92 (1.84-8.34); P<0.001]. NT pro-BNP greater than a standard prognostic threshold (>300 pg ml-1) was more frequent in patients with HRR≤12 [96/529 (18.1%) vs HRR>12 59/745 (7.9%); OR, 2.58 (1.82-3.64); P<0.001]. CONCLUSIONS: Impaired HRR is associated with an increased risk of perioperative cardiac injury. These data suggest a mechanistic role for cardiac vagal dysfunction in promoting perioperative myocardial injury.

Using the 6-minute walk test to predict disability-free survival after major surgery.

BACKGROUND: The 6-min walk test (6MWT) is a common means of functional assessment. Its relationship to disability-free survival (DFS) is uncertain. METHODS: This sub-study of the Measurement of Exercise Tolerance for Surgery study had co-primary outcome measures: correlation of the preoperative 6MWT distance with 30 day quality of recovery (15-item quality of recovery) and 12 month WHO Disability Assessment Schedule scores. The prognostic utility of the 6MWT and other risk assessment tools for 12 month DFS was assessed with logistic regression and receiver-operating-characteristic-curve analysis. RESULTS: Of 574 patients recruited, 567 (99%) completed the 6MWT. Twelve months after surgery, 16 (2.9%) patients had died and 444 (77%) had DFS. The 6MWT correlated weakly with 30 day 15-item quality of recovery (ρ=0.14; P=0.001) and 12 month WHO Disability Assessment Schedule (ρ=-0.23; P<0.0005) scores. When the cohort was split into 6MWT distance tertiles, the adjusted odds ratio of low vs high tertiles for DFS was 3.13 [95% confidence interval (CI): 1.54-6.35]. The only independent variable predictive of DFS was the Duke Activity Status Index (DASI) score (adjusted odds ratio: 1.06; P<0.0005). The area under the receiver-operating-characteristic curve for DFS was 0.63 (95% CI: 0.57-0.70) for the 6MWT, 0.60 (95% CI: 0.53-0.67) for cardiopulmonary-exercise-testing-derived peak oxygen consumption, and 0.70 (95% CI: 0.64-0.76) for the DASI score. CONCLUSIONS: Of the risk assessment tools analysed, the DASI was the most predictive of DFS. The 6MWT was safe and comparable with cardiopulmonary exercise testing for all predictive assessments. Future research should aim to determine the optimal 6MWT distance thresholds for risk prediction.

Preoperative systemic inflammation and perioperative myocardial injury: prospective observational multicentre cohort study of patients undergoing non-cardiac surgery.

BACKGROUND: Systemic inflammation is pivotal in the pathogenesis of cardiovascular disease. As inflammation can directly cause cardiomyocyte injury, we hypothesised that established systemic inflammation, as reflected by elevated preoperative neutrophil-lymphocyte ratio (NLR) >4, predisposes patients to perioperative myocardial injury. METHODS: We prospectively recruited 1652 patients aged ≥45 yr who underwent non-cardiac surgery in two UK centres. Serum high sensitivity troponin T (hsTnT) concentrations were measured on the first three postoperative days. Clinicians and investigators were blinded to the troponin results. The primary outcome was perioperative myocardial injury, defined as hsTnT≥14 ng L-1 within 3 days after surgery. We assessed whether myocardial injury was associated with preoperative NLR>4, activated reactive oxygen species (ROS) generation in circulating monocytes, or both. Multivariable logistic regression analysis explored associations between age, sex, NLR, Revised Cardiac Risk Index, individual leukocyte subsets, and myocardial injury. Flow cytometric quantification of ROS was done in 21 patients. Data are presented as n (%) or odds ratio (OR) with 95% confidence intervals. RESULTS: Preoperative NLR>4 was present in 239/1652 (14.5%) patients. Myocardial injury occurred in 405/1652 (24.5%) patients and was more common in patients with preoperative NLR>4 [OR: 2.56 (1.92-3.41); P<0.0001]. Myocardial injury was independently associated with lower absolute preoperative lymphocyte count [OR 1.80 (1.50-2.17); P<0.0001] and higher absolute preoperative monocyte count [OR 1.93 (1.12-3.30); P=0.017]. Monocyte ROS generation correlated with NLR (r=0.47; P=0.03). CONCLUSIONS: Preoperative NLR>4 is associated with perioperative myocardial injury, independent of conventional risk factors. Systemic inflammation may contribute to the development of perioperative myocardial injury. CLINICAL TRIAL REGISTRATION: NCT01842568.

Arterial pulse pressure and postoperative morbidity in high-risk surgical patients.

BACKGROUND: Systemic arterial pulse pressure (systolic minus diastolic pressure) ≤53 mm Hg in patients with cardiac failure is correlated with reduced stroke volume and is independently associated with accelerated morbidity and mortality. Given that deconditioned surgical and heart failure patients share similar cardiopulmonary physiology, we examined whether lower pulse pressure is associated with excess morbidity after major surgery. METHODS: This was a prospective observational cohort study of patients deemed by their preoperative assessors to be at higher risk of postoperative morbidity. Preoperative pulse pressure was calculated before cardiopulmonary exercise testing. The primary outcome was any morbidity (PostOperative Morbidity Survey) occurring within 5 days of surgery, stratified by pulse pressure threshold ≤53 mm Hg. The relationship between pulse pressure, postoperative morbidity, and oxygen pulse (a robust surrogate for left ventricular stroke volume) was examined using logistic regression analysis (accounting for age, sex, BMI, cardiometabolic co-morbidity, and operation type). RESULTS: The primary outcome occurred in 578/660 (87.6%) patients, but postoperative morbidity was more common in 243/ 660 patients with preoperative pulse pressure ≤53 mm Hg{odds ratio (OR): 2.24 [95% confidence interval (CI): 1.29-3.38]; P<0.001). Pulse pressure ≤53 mm Hg [OR:1.23 (95% CI: 1.03-1.46); P=0.02] and type of surgery were independently associated with all-cause postoperative morbidity (multivariate analysis). Oxygen pulse <90% of population-predicted normal values was associated with pulse pressure ≤ 53 mm Hg [OR: 1.93 (95% CI: 1.32-2.84); P=0.007]. CONCLUSIONS: In deconditioned surgical patients, lower preoperative systemic arterial pulse pressure is associated with excess morbidity. These data are strikingly similar to meta-analyses identifying low pulse pressure as an independent risk factor for adverse outcomes in cardiac failure. Low preoperative pulse pressure is a readily available measure, indicating that detailed physiological assessment may be warranted. CLINICAL TRIAL REGISTRATION: ISRCT registry, ISRCTN88456378.

The surgical safety checklist and patient outcomes after surgery: a prospective observational cohort study, systematic review and meta-analysis.

BACKGROUND: The surgical safety checklist is widely used to improve the quality of perioperative care. However, clinicians continue to debate the clinical effectiveness of this tool. METHODS: Prospective analysis of data from the International Surgical Outcomes Study (ISOS), an international observational study of elective in-patient surgery, accompanied by a systematic review and meta-analysis of published literature. The exposure was surgical safety checklist use. The primary outcome was in-hospital mortality and the secondary outcome was postoperative complications. In the ISOS cohort, a multivariable multi-level generalized linear model was used to test associations. To further contextualise these findings, we included the results from the ISOS cohort in a meta-analysis. Results are reported as odds ratios (OR) with 95% confidence intervals. RESULTS: We included 44 814 patients from 497 hospitals in 27 countries in the ISOS analysis. There were 40 245 (89.8%) patients exposed to the checklist, whilst 7508 (16.8%) sustained ≥1 postoperative complications and 207 (0.5%) died before hospital discharge. Checklist exposure was associated with reduced mortality [odds ratio (OR) 0.49 (0.32-0.77); P<0.01], but no difference in complication rates [OR 1.02 (0.88-1.19); P=0.75]. In a systematic review, we screened 3732 records and identified 11 eligible studies of 453 292 patients including the ISOS cohort. Checklist exposure was associated with both reduced postoperative mortality [OR 0.75 (0.62-0.92); P<0.01; I2=87%] and reduced complication rates [OR 0.73 (0.61-0.88); P<0.01; I2=89%). CONCLUSIONS: Patients exposed to a surgical safety checklist experience better postoperative outcomes, but this could simply reflect wider quality of care in hospitals where checklist use is routine.

A systematic review and consensus definitions for standardised end-points in perioperative medicine: pulmonary complications.

BACKGROUND: There is a need for robust, clearly defined, patient-relevant outcome measures for use in randomised trials in perioperative medicine. Our objective was to establish standard outcome measures for postoperative pulmonary complications research. METHODS: A systematic literature search was conducted using MEDLINE, Web of Science, SciELO, and the Korean Journal Database. Definitions were extracted from included manuscripts. We then conducted a three-stage Delphi consensus process to select the optimal outcome measures in terms of methodological quality and overall suitability for perioperative trials. RESULTS: From 2358 records, the full texts of 81 manuscripts were retrieved, of which 45 met the inclusion criteria. We identified three main categories of outcome measure specific to perioperative pulmonary outcomes: (i) composite outcome measures of multiple pulmonary outcomes (27 definitions); (ii) pneumonia (12 definitions); and (iii) respiratory failure (six definitions). These were rated by the group according to suitability for routine use. The majority of definitions were given a low score, and many were imprecise, difficult to apply consistently, or both, in large patient populations. A small number of highly rated definitions were identified as appropriate for widespread use. The group then recommended four outcome measures for future use, including one new definition. CONCLUSIONS: A large number of postoperative pulmonary outcome measures have been used, but most are poorly defined. Our four recommended outcome measures include a new definition of postoperative pulmonary complications, incorporating an assessment of severity. These definitions will meet the needs of most clinical effectiveness trials of treatments to improve postoperative pulmonary outcomes.

Association of preoperative anaemia with postoperative morbidity and mortality: an observational cohort study in low-, middle-, and high-income countries.

BACKGROUND: Anaemia is associated with poor postoperative outcomes, but few studies have described the impact of preoperative anaemia in low- and middle- (LMICs), and high-income countries (HICs). METHODS: This was a planned analysis of data collected during an international 7 day cohort study of adults undergoing elective inpatient surgery. The primary outcome was in-hospital death, and the secondary outcomes were in-hospital complications. Anaemia was defined as haemoglobin <12 g dl-1 for females and <13 g dl-1 for males. Hierarchical three-level mixed-effect logistic regression models were constructed to examine the associations between preoperative anaemia and outcomes. RESULTS: We included 38 770 patients from 474 hospitals in 27 countries of whom 11 675 (30.1%) were anaemic. Of these, 6886 (17.8%) patients suffered a complication and 198 (0.5%) died. Patients from LMICs were younger with lower ASA physical status scores, but a similar prevalence of anaemia [LMIC: 5072 (32.5%) of 15 585 vs HIC: 6603 (28.5%) of 23 185]. Patients with moderate [odds ratio (OR): 2.70; 95% confidence interval (CI): 1.88-3.87] and severe anaemia (OR: 4.09; 95% CI: 1.90-8.81) were at an increased risk of death in both HIC and LMICs. Complication rates increased with the severity of anaemia. Compared with patients in LMICs, those in HICs experienced fewer complications after an interaction term analysis [LMIC (OR: 0.92; 95% CI: 0.87-0.97) vs HIC (OR: 0.86; 95% CI: 0.84-0.87); P<0.01]. CONCLUSIONS: One-third of patients undergoing elective surgery are anaemic. These patients have an increased risk of complications and death. The prevalence of anaemia is similar amongst patients in LMICs despite their younger age and lower risk profile. CLINICAL TRIAL REGISTRATION: ISRCTN51817007.

The ASOS Surgical Risk Calculator: development and validation of a tool for identifying African surgical patients at risk of severe postoperative complications.

BACKGROUND: The African Surgical Outcomes Study (ASOS) showed that surgical patients in Africa have a mortality twice the global average. Existing risk assessment tools are not valid for use in this population because the pattern of risk for poor outcomes differs from high-income countries. The objective of this study was to derive and validate a simple, preoperative risk stratification tool to identify African surgical patients at risk for in-hospital postoperative mortality and severe complications. METHODS: ASOS was a 7-day prospective cohort study of adult patients undergoing surgery in Africa. The ASOS Surgical Risk Calculator was constructed with a multivariable logistic regression model for the outcome of in-hospital mortality and severe postoperative complications. The following preoperative risk factors were entered into the model; age, sex, smoking status, ASA physical status, preoperative chronic comorbid conditions, indication for surgery, urgency, severity, and type of surgery. RESULTS: The model was derived from 8799 patients from 168 African hospitals. The composite outcome of severe postoperative complications and death occurred in 423/8799 (4.8%) patients. The ASOS Surgical Risk Calculator includes the following risk factors: age, ASA physical status, indication for surgery, urgency, severity, and type of surgery. The model showed good discrimination with an area under the receiver operating characteristic curve of 0.805 and good calibration with c-statistic corrected for optimism of 0.784. CONCLUSIONS: This simple preoperative risk calculator could be used to identify high-risk surgical patients in African hospitals and facilitate increased postoperative surveillance. CLINICAL TRIAL REGISTRATION: NCT03044899.

Acute kidney injury and mortality 1 year after major non-cardiac surgery.

BACKGROUND: Even mild and transient acute kidney injury (AKI), defined by increases in serum creatinine level, has been associated with adverse outcomes after major surgery. However, characteristic decreases in creatinine concentration during major illness could confound accurate assessment of postoperative AKI. METHODS: In a single-hospital, retrospective cohort study of non-cardiac surgery, the association between postoperative AKI, defined using the Kidney Disease: Improving Global Outcomes criteria, and 1-year survival was modelled using a multivariable Cox proportional hazards analysis. Factors associated with development of AKI were examined by means of multivariable logistic regression. Temporal changes in serum creatinine during and after the surgical admission in patients with and without AKI were compared. RESULTS: Some 1869 patients were included in the study, of whom 128 (6·8 per cent) sustained AKI (101 stage 1, 27 stage 2-3). Seventeen of the 128 patients with AKI (13·3 per cent) died in hospital compared with 16 of 1741 (0·9 per cent) without AKI (P < 0·001). By 1 year, 34 patients with AKI (26·6 per cent) had died compared with 106 (6·1 per cent) without AKI (P < 0·001). Over the 8-365 days after surgery, AKI was associated with an adjusted hazard ratio for death of 2·96 (95 per cent c.i. 1·86 to 4·71; P < 0·001). Among hospital survivors without AKI, the creatinine level fell consistently (median difference at discharge versus baseline -7 (i.q.r. -15 to 0) µmol/l), but not in those with AKI (0 (-16 to 26) µmol/l) (P < 0·001). CONCLUSION: Although the majority of postoperative AKI was mild, there was a strong association with risk of death in the year after surgery. Underlying decreases in serum creatinine concentration after major surgery could lead to underestimation of AKI severity and overestimation of recovery.

Effect of day of the week on short- and long-term mortality after emergency general surgery.

BACKGROUND: The effect of day of the week on outcome after surgery is the subject of debate. The aim was to determine whether day of the week of emergency general surgery alters short- and long-term mortality. METHODS: This was an observational study of all patients undergoing emergency general surgery in Scotland between 1 January 2005 and 31 December 2007, followed to 2012. Multilevel logistic and Cox proportional hazards regression were used to assess the effect of day of the week of surgery on outcome after adjustment for case mix and risk factors. The primary outcome was perioperative mortality; the secondary outcome was overall survival. RESULTS: A total of 50 844 patients were identified, of whom 31 499 had an emergency procedure on Monday to Thursday and 19 345 on Friday to Sunday. Patients undergoing surgery at the weekend were younger (mean 45·9 versus 47·5 years; P < 0·001) and had fewer co-morbidities, but underwent riskier and/or more complex procedures (P < 0·001). Patients who had surgery at the weekend were more likely to have been operated on sooner than those who had weekday surgery (mean time from admission to operation 1·2 versus 1·6 days; P < 0·001). No difference in perioperative mortality (odds ratio 1·00, 95 per cent c.i. 0·89 to 1·13; P = 0·989) or overall survival (hazard ratio 1·01, 0·97 to 1·06; P = 0·583) was observed when surgery was performed at the weekend. There was no difference in overall survival after surgery undertaken on any particular day compared with Wednesday; a borderline reduction in perioperative mortality was seen on Tuesday. CONCLUSION: There was no difference in short- or long-term mortality following emergency general surgery at the weekend, compared with mid-week.

Are we close to the ideal intravenous fluid?

The approach to i.v. fluid therapy for hypovolaemia may significantly influence outcomes for patients who experience a systemic inflammatory response after sepsis, trauma, or major surgery. Currently, there is no single i.v. fluid agent that meets all the criteria for the ideal treatment for hypovolaemia. The physician must choose the best available agent(s) for each patient, and then decide when and how much to administer. Findings from large randomized trials suggest that some colloid-based fluids, particularly starch-based colloids, may be harmful in some situations, but it is unclear whether they should be withdrawn from use completely. Meanwhile, crystalloid fluids, such as saline 0.9% and Ringer's lactate, are more frequently used, but debate continues over which preparation is preferable. Perhaps most importantly, it remains unclear how to select the optimal dose of fluid in different patients and different clinical scenarios. There is good reason to believe that both inadequate and excessive i.v. fluid administration may lead to poor outcomes, including increased risk of infection and organ dysfunction, for hypovolaemic patients. In this review, we summarize the current knowledge on this topic and identify some key pitfalls and some areas of agreed best practice.

Frequency of surgical treatment and related hospital procedures in the UK: a national ecological study using hospital episode statistics.

BACKGROUND: Despite evidence of high activity, the number of surgical procedures performed in UK hospitals, their cost and subsequent mortality remain unclear. METHODS: Time-trend ecological study using hospital episode data from England, Scotland, Wales and Northern Ireland. The primary outcome was the number of in-hospital procedures, grouped using three increasingly specific categories of surgery. Secondary outcomes were all-cause mortality, length of hospital stay and healthcare costs according to standard National Health Service tariffs. RESULTS: Between April 1, 2009 and March 31, 2014, 39 631 801 surgical patient episodes were recorded. There was an annual average of 7 926 360 procedures (inclusive category), 5 104 165 procedures (intermediate category) and 1 526 421 procedures (restrictive category). This equates to 12 537, 8073 and 2414 procedures per 100 000 population per year, respectively. On average there were 85 181 deaths (1.1%) within 30 days of a procedure each year, rising to 178 040 deaths (2.3%) after 90 days. Approximately 62.8% of all procedures were day cases. Median length of stay for in-patient procedures was 1.7 (1.3-2.0) days. The total cost of surgery over the 5 yr period was £54.6 billion ($104.4 billion), representing an average annual cost of £10.9 billion (inclusive), £9.5 billion (intermediate) and £5.6 billion (restrictive). For each category, the number of procedures increased each year, while mortality decreased. One-third of all mortalities in national death registers occurred within 90 days of a procedure (inclusive category). CONCLUSIONS: The number of surgical procedures in the UK varies widely according to definition. The number of procedures is slowly increasing whilst the number of deaths is decreasing.