Intensive Care National Audit & Research Centre Research Articles

Association of Annual Intensive Care Unit Sepsis Caseload With Hospital Mortality From Sepsis in the United Kingdom, 2010-2016

Sepsis is associated with a high burden of inpatient mortality. Treatment in intensive care units (ICUs) that have more experience treating patients with sepsis may be associated with lower mortality. To assess the association between the volume of patients with sepsis receiving care in an ICU and hospital mortality from sepsis in the UK. This retrospective cohort study used data from adult patients with sepsis from 231 UK ICUs between 2010 and 2016. Demographic and clinical data were extracted from the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme database. Data were analyzed from January 1, 2010, to December 31, 2016. Annual sepsis case volume in an ICU in the year of a patient's admission. Hospital mortality after ICU admission for sepsis assessed using a mixed-effects logistic model in a 3-level hierarchical structure based on the number of individual patients nested in years nested within ICUs. Among 273 001 patients included in the analysis, the median age was 66 years (interquartile range, 53-76 years), 148 149 (54.3%) were male, and 248 275 (91.0%) were White. The mean ICNARC-2018 illness severity score was 21.0 (95% CI, 20.9-21.0). Septic shock accounted for 19.3% of patient admissions, and 54.3% of patients required mechanical ventilation. The median annual sepsis volume per ICU was 242 cases (interquartile range, 177-334 cases). The study identified a significant association between the volume of sepsis cases in the ICU and mortality from sepsis; in the logistic regression model, hospital mortality was significantly lower among patients admitted to ICUs in the highest quartile of sepsis volume compared with the lowest quartile (odds ratio [OR], 0.89; 95% CI, 0.82-0.96; P = .002). With volume modeled as a restricted cubic spline, treatment in a larger ICU was associated with lower hospital mortality. A lower annual volume threshold of 215 patients above which hospital mortality decreased significantly was found; 38.8% of patients were treated in ICUs below this threshold volume. There was no significant interaction between ICU volume and severity of illness as described by the ICNARC-2018 score (β [SE], -0.00014 [0.00024]; P = .57). The findings suggest that patients with sepsis in the UK have higher odds of survival if they are treated in an ICU with a larger sepsis case volume. The benefit of a high sepsis case volume was not associated with the severity of the sepsis episode.

PUK14 ACUTE Renal Failure during COVID-19 and Its LONG-TERM IMPACT on Health System

SARS-CoV-2 is known for its respiratory impact, but also affects other organs such as kidneys. According to the Intensive Care National Audit & Research Centre (ICNARC) report of June 5th, 26% of critically ill COVID-19 patients required acute renal support (ARS), in comparison to 5-10% of the general critically ill patients. This threefold increase led to challenges in product supply and thereby in care provision. ARS is associated with an increased risk in chronic dialysis dependency, which with scarcity of appropriate therapies could be accelerated.

Commentary: Obesity: The “Achilles heel” for COVID-19?

Commentary: Obesity: The “Achilles heel” for COVID-19?

The critically ill mother: Recognition and management (who, where and how?)

There is an ongoing debate about the management of the critically ill mother, notably with regards to who should manage this group of patients (the intensivist, the obstetric anaesthetist, or the obstetrician?) and where is the ideal place to manage them (labour ward, obstetric high dependency unit or the intensive care unit?). To make the most appropriate choice, an understanding of how to recognise maternal critical illness is paramount. Using the modified early obstetric warning system score (MEOWS) for obstetric patients is a useful tool 1. MEOWS looks at additional parameters to the standard early warning systems parameters with modified triggers to suit the altered physiology in the pregnant patient. Other predictors like APACHE and SOFA scores may also be used to predict maternal mortality 2. Data from several national audit and surveillance programs such as MBRRACE-UK (Mothers and Babies: Reducing Risk Through Audits and Confidential Enquiries across the UK) 3, UKOSS (The UK Obstetric Surveillance System), and ICNARC (Intensive Care National Audit & Research Centre) are used to aid the understanding of why mothers die in childbirth and up to six weeks postpartum and which critically ill mothers are admitted to the intensive care unit and the reason for their admission 4. Audit reports show that a significant number of deaths reported in the maternal mortality reports are associated with suboptimal care. There is a great need for an evidence-based triage system for the critically ill obstetric patient in order to help clinicians direct them to the appropriate level of care and avoid situations of suboptimal care. Regionalizing maternal critical care may help develop this triage system by increasing the exposure to such patients. Deciding on who should manage these patients will depend on the level of training and expertise of the team members involved in the management on how to detect an acutely deteriorating mother. The team members should include obstetricians, anaesthetists, intensivists, intensive care nurses and midwives. The training can be achieved using different educational approaches that are competency-based to improve the knowledge and skills in detecting signs of deterioration in order to take the appropriate actions. Multidisciplinary teams should train together using simulation-based learning focusing on human factors and communication skills 5. Deciding on where these patients should be managed will depend on the level of organ support and monitoring available as well as the access to support services such as obstetric and neonatal services, regardless of what the terminology of that location is. The different models of delivering care to the critically ill obstetric patient with the different requirements for these areas are highlighted in Table 1. Taking all the previous factors into consideration will help find the answer to the WHO, WHERE and HOW question.

Prediction of Postoperative Outcomes and Long-Term Survival in Cardiac Surgical Patients Using the Intensive Care National Audit & Research Centre Score

Scoring systems used in cardiac surgery, such as the European System for Cardiac Operative Risk Evaluation and the Society of Thoracic Surgeons scoring systems, do not adjust for events that take place intraoperatively. The authors hypothesized that intensive care unit scoring systems such as the Intensive Care National Audit & Research Centre (ICNARC) could predict accurately not only in-hospital mortality, but also other significant complications, as well as long-term survival after cardiac surgery. Prospective cohort study using perioperative data from the ICNARC Audit and Dendrite database. Single tertiary referral cardiac surgery center. A total of 4,446 consecutive cardiac surgical patients who had surgery between January 2011 and April 2018. Comparison of scoring systems to predict postoperative outcomes. Receiver operating curves (ROCs) were used to evaluate how well the ICNARC scores predicted in-hospital mortality and postoperative complications (renal failure, pulmonary complications, gastrointestinal complications, and multiorgan failure). Cox regression analysis was used to determine factors affecting long-term survival. The C-indices for the ROC graphs for the ICNARC score were 0.840 for in-hospital mortality, 0.858 for renal failure, 0.665 for pulmonary complications, 0.764 for gastrointestinal complications, 0.702 for neurological complications in general and 0.654 for confusion, and 0.885 for multiorgan failure. From Cox regression analysis, the significant (p < 0.05) predictors of midterm mortality (5 years) were a higher ICNARC score, a higher age at surgery, chronic obstructive pulmonary disease, preoperative renal failure, preoperative neurological comorbidity, arteriopathy, and non-coronary artery bypass graft surgery. The ICNARC scoring system is simple and can be used as an early warning screening tool to predict which patients are at higher risk for postoperative organ failure.

Increasing survival after admission to UK critical care units following cardiopulmonary resuscitation.

BackgroundIn recent years there have been many developments in post-resuscitation care. We have investigated trends in patient characteristics and outcome following admission to UK critical care units following cardiopulmonary resuscitation (CPR) for the period 2004–2014. Our hypothesis is that there has been a reduction in risk-adjusted mortality during this period.MethodsWe undertook a prospectively defined, retrospective analysis of the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme Database (CMPD) for the period 1 January 2004 to 31 December 2014. Admissions, mechanically ventilated in the first 24 hours in the critical care unit and admitted following CPR, defined as the delivery of chest compressions in the 24 hours before admission, were identified. Case mix, withdrawal, outcome and activity were described annually for all admissions identified as post-cardiac arrest admissions, and separately for out-of-hospital cardiac arrest and in-hospital cardiac arrest. To assess whether in-hospital mortality had improved over time, hierarchical multivariate logistic regression models were constructed, with in-hospital mortality as the dependent variable, year of admission as the main exposure variable and intensive care unit (ICU) as a random effect. All analyses were repeated using only the data from those ICUs contributing data throughout the study period.ResultsDuring the period 2004–2014 survivors of cardiac arrest accounted for an increasing proportion of mechanically ventilated admissions to ICUs in the ICNARC CMPD (9.0 % in 2004 increasing to 12.2 % in 2014). Risk-adjusted hospital mortality following admission to ICU after cardiac arrest has decreased significantly during this period (OR 0.96 per year). Over this time, the ICU length of stay and time to treatment withdrawal has increased significantly. Re-analysis including only those 116 ICUs contributing data throughout the study period confirmed all the results of the primary analysis.ConclusionsRisk-adjusted hospital mortality following admission to ICU after cardiac arrest has decreased significantly during the period 2004–2014. Over the same period the ICU length of stay and time to treatment withdrawal has increased significantly.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-016-1390-6) contains supplementary material, which is available to authorized users.

Sepsis Patients with First and Second-Hit Infections Show Different Outcomes Depending on the Causative Organism.

Objective: With improving rates of initial survival in severe sepsis, second-hit infections that occur following resolution of the primary insult carry an increasing burden of morbidity. However, despite the clinical relevance of these infections, no data are available on differential outcomes in patients with first and second-hit infections depending on the nature of the causative organism. This study aims to explore any differences in these subgroups.Design: In a retrospective, observational cohort study, the United Kingdom Intensive Care National Audit & Research Centre (ICNARC) database was used to explore the outcomes of patient with first-hit infections leading to sepsis, and sepsis patients with second-hit infections grouped according to the Gram status of the causative organism.Setting: General critical care units in England, Wales, and Northern Ireland participating in the ICNARC programme between 1 January, 2007 and 30 June, 2012.Patients: Patient groups analyzed included 2119 patients with and 1319 patients without sepsis who developed an intensive care unit acquired infection in blood. Subgroups included patients with trauma, emergency neurosurgery, elective surgery, and cardiogenic shock.Measurements and main results: Gram-negative organisms were associated with poorer outcomes in first-hit infections. The 90-day mortality of patients who developed a Gram-negative infection was 43.6% following elective surgery and 27.9% following trauma. This compared with a mortality of 25.6 and 20.6%, respectively, in Gram-positive infections. Unexpectedly, an inverse relationship between Gram status and mortality was observed in second-hit infections. Patients with an initial diagnosis of sepsis who developed secondary infections caused by Gram-negative organisms had a 90-day mortality of 40.4%, compared with 43.6% in Gram-positive infections.Conclusions: Our study identifies a fundamental difference in patient outcomes between first-hit and second-hit bacterial infections, which may be due to genetic, microbiological, immunological, and environmental factors. This finding has direct implications for risk stratification and defines future research priorities.

Comparing mortality among adult, general intensive care units in England with varying intensivist cover patterns: a retrospective cohort study

IntroductionResearch has demonstrated that intensivist-led care of the critically ill is associated with reduced intensive care unit (ICU) and hospital mortality. The objective of this study was to evaluate whether a relation exists between intensivist cover pattern (for example, number of days of continuous cover) and patient outcomes among adult general ICUs in England.MethodsWe conducted a retrospective cohort study by using data from a pooled case mix and outcome database of adult general critical care units participating in the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme. Consecutive admissions to participating units for the years 2010 to 2011 were linked to a survey of intensivist cover practices. Our primary outcome of interest was mortality at ultimate discharge from acute-care hospital.ResultsThe analysis included 80,122 patients admitted to 130 ICUs in 128 hospitals. Multivariable logistic regression analysis was used to assess the relation between intensivist cover patterns (days of continuous cover, grade of physician staffing at nighttime, and frequency of daily handovers) and acute hospital mortality, adjusting for patient case mix. No relation was seen between days of continuous cover by a single intensivist or grade of physician staffing at nighttime and acute hospital mortality. Acute hospital mortality and ICU length of stay were not associated with intensivist characteristics, intensivist full-time equivalents per bed, or years of clinical experience. Intensivist participation in handover was associated with increased mortality (odds ratio, 1.27; 95% confidence interval, 1.04 to 1.55); however, only nine units reported no intensivist participation.ConclusionsWe found no relation between days of continuous cover by a single intensivist or grade of physician staffing at nighttime and patient outcomes in adult, general ICUs in England. Intensivist participation in handover was associated with increased mortality; further research to confirm or refute this finding is required.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-014-0491-3) contains supplementary material, which is available to authorized users.

Nurse staffing, medical staffing and mortality in Intensive Care: An observational study

ObjectivesTo investigate whether the size of the workforce (nurses, doctors and support staff) has an impact on the survival chances of critically ill patients both in the intensive care unit (ICU) and in the hospital. BackgroundInvestigations of intensive care outcomes suggest that some of the variation in patient survival rates might be related to staffing levels and workload, but the evidence is still equivocal. DataInformation about patients, including the outcome of care (whether the patient lived or died) came from the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme. An Audit Commission survey of ICUs conducted in 1998 gave information about staffing levels. The merged dataset had information on 65 ICUs and 38,168 patients. This is currently the best available dataset for testing the relationship between staffing and outcomes in UK ICUs. DesignA cross-sectional, retrospective, risk adjusted observational study. MethodsMultivariable, multilevel logistic regression. Outcome MeasuresICU and in-hospital mortality. ResultsAfter controlling for patient characteristics and workload we found that higher numbers of nurses per bed (odds ratio: 0.90, 95% confidence interval: [0.83, 0.97]) and higher numbers of consultants (0.85, [0.76, 0.95]) were associated with higher survival rates. Further exploration revealed that the number of nurses had the greatest impact on patients at high risk of death (0.98, [0.96, 0.99]) whereas the effect of medical staffing was unchanged across the range of patient acuity (1.00, [0.97, 1.03]). No relationship between patient outcomes and the number of support staff (administrative, clerical, technical and scientific staff) was found. Distinguishing between direct care and supernumerary nurses and restricting the analysis to patients who had been in the unit for more than 8h made little difference to the results. Separate analysis of in-unit and in-hospital survival showed that the clinical workforce in intensive care had a greater impact on ICU mortality than on hospital mortality which gives the study additional credibility. ConclusionThis study supports claims that the availability of medical and nursing staff is associated with the survival of critically ill patients and suggests that future studies should focus on the resources of the health care team. The results emphasise the urgent need for a prospective study of staffing levels and the organisation of care in ICUs.

Comparing mortality among adult, general intensive care units in England with varying intensivist cover patterns: a retrospective cohort study

IntroductionResearch has demonstrated that intensivist-led care of the critically ill is associated with reduced intensive care unit (ICU) and hospital mortality. The objective of this study was to evaluate whether a relation exists between intensivist cover pattern (for example, number of days of continuous cover) and patient outcomes among adult general ICUs in England.MethodsWe conducted a retrospective cohort study by using data from a pooled case mix and outcome database of adult general critical care units participating in the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme. Consecutive admissions to participating units for the years 2010 to 2011 were linked to a survey of intensivist cover practices. Our primary outcome of interest was mortality at ultimate discharge from acute-care hospital.ResultsThe analysis included 80,122 patients admitted to 130 ICUs in 128 hospitals. Multivariable logistic regression analysis was used to assess the relation between intensivist cover patterns (days of continuous cover, grade of physician staffing at nighttime, and frequency of daily handovers) and acute hospital mortality, adjusting for patient case mix. No relation was seen between days of continuous cover by a single intensivist or grade of physician staffing at nighttime and acute hospital mortality. Acute hospital mortality and ICU length of stay were not associated with intensivist characteristics, intensivist full-time equivalents per bed, or years of clinical experience. Intensivist participation in handover was associated with increased mortality (odds ratio, 1.27; 95% confidence interval, 1.04 to 1.55); however, only nine units reported no intensivist participation.ConclusionsWe found no relation between days of continuous cover by a single intensivist or grade of physician staffing at nighttime and patient outcomes in adult, general ICUs in England. Intensivist participation in handover was associated with increased mortality; further research to confirm or refute this finding is required.

It’s getting better all the time? Using secular trends to understand the impact of neurocritical care

It’s getting better all the time? Using secular trends to understand the impact of neurocritical care

The effect of secular trends and specialist neurocritical care on mortality for patients with intracerebral haemorrhage, myasthenia gravis and Guillain–Barré syndrome admitted to critical care

To analyse mortality for spontaneous intracerebral haemorrhage (ICH), myasthenia gravis (MG) and Guillain-Barré syndrome (GBS) from 1996 to 2009 in UK intensive care units (ICUs). We used the Intensive Care National Audit & Research Centre (ICNARC) database. We identified specialised neurosciences critical care units (NCCUs) (n=16), general ICUs with full neurological support (n=48) and general ICUs with limited neurological support (n=138) and undertook descriptive analyses for each condition. Poisson regression was used to identify trends in admission rates, median regression to identify trends in lengths of stay (LOS), and logistic regression (Wald test) to analyse interaction between unit type and time period; odds ratios were calculated for hospital mortality associated with unit types. For ICH (n=10,313 cases), overall ICU mortality was 42.4%, and acute hospital mortality 62.1%. In NCCU, LOS was longer, but mortality lower, and over time, mortality from ICH decreased faster. For MG (n=1,064 cases) and GBS (n=1,906 cases), overall mortality was relatively high (MG: 8.7% ICU mortality and 22% acute hospital mortality; GBS: 7.7 and 16.7%, respectively); overall mortality did not decrease over time. This first large-scale analysis of outcomes in acute neurological disease in the UK demonstrates real-life mortality higher than published series. NCCU care is associated with increased survival in conditions requiring highly specialised intensive care techniques, but high-quality step-down care is pivotal in others. Strategies that truly improve outcomes must integrate emergency department management, ICU admission criteria, NCCU treatment, high-quality step-down care and neurorehabilitation.

Comments on O’Brien et al.: Prevalence and outcome of cirrhosis patients admitted to UK intensive care: a comparison against dialysis-dependent chronic renal failure patients

Dear Editor, We read with interest the article by O’Brien et al. [1] on the prevalence and outcome of patients with cirrhosis admitted to British ICUs. While the authors raise important points regarding the high mortality of decompensated cirrhosis and the increasing burden placed on critical care services by such patients, we feel their interpretation should not go unchallenged as there are several major limitations to the analysis that mitigate their bold and nihilistic conclusions. Firstly, as the authors themselves partly acknowledge, chronic renal failure is clearly not the same as hepatic failure. The outcome for patients with dialysis dependent endstage renal disease (ESRD) admitted to the ICU is surprisingly good, is better than that of patients admitted with acute kidney injury and has frequently been reported to be little different from that of the general ICU population [2]. In addition, a treatment does exist that directly addresses the underlying organ failure in ESRD, but no such equivalent is available for hepatic failure. We do not believe therefore that the authors’ argument that the two conditions are comparable for the sake of their analysis can be in anyway justified. The second shortcoming of the paper relates to its use of the Intensive Care National Audit & Research Centre (ICNARC) database. This brings with it several major problems in terms of data availability. The ICNARC and Acute Physiology and Chronic Health Evaluation II (APACHE II) models do not collect parameters that quantify either the presence or severity of liver disease. This limits the utility of these models to predict outcome in patients with liver disease, likely explaining why the ICNARC and APACHE II scores were higher for dialysis-dependent ESRD patients compared with patients with cirrhosis and significantly under-predicting mortality for this latter group. In contrast, evidence does exist that the Sequential Organ Failure Assessment (SOFA) score (which includes bilirubin as one of its parameters) performs better than APACHE II score in predicting outcome in patients with cirrhosis admitted to the ICU [3]. A further weakness of the article is the inability to identify the specific reason for ICU admission. For example, variceal bleeding is the commonest reason for ICU admission in many series [3], and ICU mortality has been demonstrated to have fallen threefold between 1980 and 2000 [4]. However, there is no way to interpret the authors’ data in the absence of specific admission data. It is undeniable that mortality in patients with cirrhosis who develop multiple organ failure is high and that the development of sepsis is a grave prognostic sign, but we would challenge the assertion that we should seek to identify earlier those patients with a poor prognosis so we can exclude them from critical care. Rather, our focus should be to more rapidly identify sepsis and organ dysfunction and admit such patients earlier to critical care units to prevent further deterioration in organ function with its associated increase in mortality risk. Such an approach, which is in direct contrast to the prognostic pessimism proposed by the authors, may then begin to deliver the improvement in outcome seen in severe sepsis in recent years [5] and produce further increases in survival in patients with cirrhosis above the 5 % reduction in mortality over time that the authors report.

Prevalence and outcome of cirrhosis patients admitted to UK intensive care: a comparison against dialysis-dependent chronic renal failure patients: Reply to comments by Mason and Yeoman

Dear Editor, We thank Drs Mason and Yeoman for their comments on our paper [1] as these raise a number of very interesting points. However, we would challenge the statement that these points mitigate against our conclusions. As mentioned in the previous reply to Drs Berry and Thompson [2], we do not wish to be seen as champions of nihilism for patients with cirrhosis; rather, our pessimistic conclusions simply reflect the data presented. Indeed, despite improvements in many aspects of critical care over the last 20 years, ICU mortality rates associated with cirrhosis remain very high. We felt that it was time for a change in the message from ‘‘we must try harder’’ to something bolder. It is very hard to advocate continuing ICU care when mortality rates exceed 85–90 %, especially as the vast majority of patients will not be eligible for transplantation. We perhaps should have added a section about optimising pre-ICU care and feel the authors’ critical care bundle suggestion has considerable merit, although whether this would have a benefit on mortality rates remains of course uncertain. However, the suggestion that cirrhosis patients be admitted earlier to the ICU is simplistic and naive given that using Hospital Episode Statistic data we identified [100,000 patients admitted to UK hospitals 2010–2011 with complications of cirrhosis (http://www. hesonline.nhs.uk). As an alternative, we would suggest borrowing another approach from sepsis studies—that of early ‘‘goal-directed therapy’’ [3], either in the emergency room or on the acute admissions ward. Indeed, a recent study has demonstrated that delayed appropriate initial empiric antimicrobial therapy is associated with increased mortality in cirrhosis [4]. As we acknowledge in our paper, the comparison with renal replacement therapy is imperfect, and we again refer to this in our reply to Drs Berry and Thompson [2], However, this hardly mitigates against our conclusion that cirrhosis patients with organ failure have an extremely poor prognosis. Rather than labour this point, we would refer these authors to the very similar overall mortality (59.2 %) seen in patients with haematological malignancies admitted to ICU [5], as mentioned in our discussion; this is a group we hope that all will agree can be regarded as having a poor prognosis. We cannot agree that using the Intensive Care National Audit & Research Centre (ICNARC) database to examine the largest cohort of ICU admissions with liver cirrhosis reported to date can be regarded as a study weakness. We acknowledge in our discussion that neither the Acute Physiology and Chronic Health Evaluation II (APACHE II) nor ICNARC score contains information directly relating to liver failure and conclude that neither score can guide decision-making; however, the area under the receiver operating characteristic curve (AUROC) of 0.8 that is seen with the ICNARC score is comparable to that obtained using Sequential Organ Failure Assessment (SOFA) and Organ System Failure (OSF) models in other studies. Equally, the fact that these scores under-predicted mortality had not been reported before, and we thought it worthy of mention. Again, we do acknowledge in the paper that mortality associated with variceal bleeding has improved over time; as such, a breakdown of mortality associated with differing reasons for admission may have proved interesting. However, the key determinants of ICU mortality in patients with cirrhosis are sepsis and organ failure [6] and, therefore, the aim of the study was to examine these in detail.

A new risk prediction model for critical care: The Intensive Care National Audit &amp; Research Centre (ICNARC) model*

To develop a new model to improve risk prediction for admissions to adult critical care units in the UK. Prospective cohort study. The setting was 163 adult, general critical care units in England, Wales, and Northern Ireland, December 1995 to August 2003. Patients were 216,626 critical care admissions. None. The performance of different approaches to modeling physiologic measurements was evaluated, and the best methods were selected to produce a new physiology score. This physiology score was combined with other information relating to the critical care admission-age, diagnostic category, source of admission, and cardiopulmonary resuscitation before admission-to develop a risk prediction model. Modeling interactions between diagnostic category and physiology score enabled the inclusion of groups of admissions that are frequently excluded from risk prediction models. The new model showed good discrimination (mean c index 0.870) and fit (mean Shapiro's R 0.665, mean Brier's score 0.132) in 200 repeated validation samples and performed well when compared with recalibrated versions of existing published risk prediction models in the cohort of patients eligible for all models. The hypothesis of perfect fit was rejected for all models, including the Intensive Care National Audit & Research Centre (ICNARC) model, as is to be expected in such a large cohort. The ICNARC model demonstrated better discrimination and overall fit than existing risk prediction models, even following recalibration of these models. We recommend it be used to replace previously published models for risk adjustment in the UK.

Case mix, outcome and activity for patients admitted to intensive care units requiring chronic renal dialysis: a secondary analysis of the ICNARC Case Mix Programme Database

IntroductionThis report describes the case mix, outcome and activity for admissions to intensive care units (ICUs) of patients who require prior chronic renal dialysis for end-stage renal failure (ESRF), and investigates the effect of case mix factors on outcome.MethodsThis was a secondary analysis of a high-quality clinical database, namely the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme Database, which includes 276,731 admissions to 170 adult ICUs across England, Wales and Northern Ireland from 1995 to 2004.ResultsDuring the eight year study period, 1.3% (n = 3,420) of all patients admitted to ICU were receiving chronic renal dialysis before ICU admission. This represents an estimated ICU utilization of six admissions (32 bed-days) per 100 dialysis patient-years. The ESRF group was younger (mean age 57.3 years versus 59.5 years) and more likely to be male (60.2% versus 57.9%) than those without ESRF. Acute Physiology and Chronic Health Evaluation II score and Acute Physiology Score revealed greater severity of illness on admission in patients with ESRF (mean 24.7 versus 16.6 and 17.2 versus 12.6, respectively). Length of stay in ICU was comparable between groups (median 1.9 days versus 1.8 days) and ICU mortality was only slightly elevated in the ESRF group (26.3% versus 20.8%). However, the ESRF group had protracted overall hospital stay (median 25 days versus 17 days), and increased hospital mortality (45.3% versus 31.2%) and ICU readmission (9.0% vs. 4.7%). Multiple logistic regression analysis adjusted for case mix identified the increased hospital mortality to be associated with increasing age, emergency surgery and nonsurgical cases, cardiopulmonary resuscitation before ICU admission and extremes of physiological norms. The adjusted odds ratio for ultimate hospital mortality associated with chronic renal dialysis was 1.24 (95% confidence interval 1.13 to 1.37).ConclusionPatients with ESRF admitted to UK ICUs are more likely to be male and younger, with a medical cause of admission, and to have greater severity of illness than the non-ESRF population. Outcomes on the ICU were comparable between the two groups, but those patients with ESRF had greater readmission rates, prolonged post-ICU hospital stay and increased post-ICU hospital mortality. This study is by far the largest comparative outcome analysis to date in patients with ESRF admitted to the ICU. It may help to inform clinical decision-making and resource requirements for this patient population.

Case mix, outcome, and activity for admissions to UK critical care units with severe acute pancreatitis: a secondary analysis of the ICNARC Case Mix Programme Database

IntroductionSevere acute pancreatitis (SAP) requiring admission to a critical care unit is associated with high mortality and long lengths of stay. We describe the case mix, outcome, and activity of admissions with SAP who were identified from a high-quality clinical database.MethodsWe conducted a secondary analysis of the ICNARC (Intensive Care National Audit & Research Centre) Case Mix Programme Database of 219,468 admissions to 159 adult, general critical care units in England, Wales, and Northern Ireland for the period of 1995 to 2003 to identify admissions with SAP. The ability of the modified Glasgow criteria to discriminate hospital survivors from non-survivors was compared to that of the Acute Physiology and Chronic Health Evaluation (APACHE) II score and a number of individual physiological parameters.ResultsA total of 2,677 admissions with SAP were identified (1.2% of all admissions). Mortality for these admissions was 31% in the critical care unit and 42% in hospital. The median length of stay in the critical care unit was 3.8 days and was similar for survivors and non-survivors. Increasing numbers of modified Glasgow criteria were associated with increasing hospital mortality, but better discrimination was provided by the APACHE II score and by several physiological parameters.ConclusionSAP requiring critical care is associated with high mortality and long length of stay. The modified Glasgow criteria represent a simple measure of severity but were not designed to predict hospital mortality. It may be possible to develop a specific model for risk prediction in patients with SAP requiring critical care.

Process monitoring in intensive care with the use of cumulative expected minus observed mortality and risk-adjusted P charts.

IntroductionA health care system is a complex adaptive system. The effect of a single intervention, incorporated into a complex clinical environment, may be different from that expected. A national database such as the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme in the UK represents a centralised monitoring, surveillance and reporting system for retrospective quality and comparative audit. This can be supplemented with real-time process monitoring at a local level for continuous process improvement, allowing early detection of the impact of both unplanned and deliberately imposed changes in the clinical environment.MethodsDemographic and UK Acute Physiology and Chronic Health Evaluation II (APACHE II) data were prospectively collected on all patients admitted to a UK regional hospital between 1 January 2003 and 30 June 2004 in accordance with the ICNARC Case Mix Programme. We present a cumulative expected minus observed (E-O) plot and the risk-adjusted p chart as methods of continuous process monitoring. We describe the construction and interpretation of these charts and show how they can be used to detect planned or unplanned organisational process changes affecting mortality outcomes.ResultsFive hundred and eighty-nine adult patients were included. The overall death rate was 0.78 of predicted. Calibration showed excess survival in ranges above 30% risk of death. The E-O plot confirmed a survival above that predicted. Small transient variations were seen in the slope that could represent random effects, or real but transient changes in the quality of care. The risk-adjusted p chart showed several observations below the 2 SD control limits of the expected mortality rate. These plots provide rapid analysis of risk-adjusted performance suitable for local application and interpretation. The E-O chart provided rapid easily visible feedback of changes in risk-adjusted mortality, while the risk-adjusted p chart allowed statistical evaluation.ConclusionLocal analysis of risk-adjusted mortality data with an E-O plot and a risk-adjusted p chart is feasible and allows the rapid detection of changes in risk-adjusted outcome of intensive care patients. This complements the centralised national database, which is more archival and comparative in nature.

The epidemiology of severe sepsis in England, Wales and Northern Ireland, 1996 to 2004: secondary analysis of a high quality clinical database, the ICNARC Case Mix Programme Database

IntroductionTo evaluate the impact of recent evidence-based treatments for severe sepsis in routine clinical care requires an understanding of the underlying epidemiology, particularly with regard to trends over time. We interrogated a high quality clinical database to examine trends in the incidence and mortality of severe sepsis over a nine-year period.MethodsAdmissions with severe sepsis occurring at any time within 24 hours of admission to critical care were identified to an established methodology using raw physiological data from the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme Database, containing data from 343,860 admissions to 172 adult, general critical care units in England, Wales and Northern Ireland between December 1995 and January 2005. Generalised linear models were used to assess changes in the incidence, case mix, outcomes and activity of these admissions.ResultsIn total, 92,672 admissions (27.0%) were identified as having severe sepsis in the first 24 hours following admission. The percentage of admissions with severe sepsis during the first 24 hours rose from 23.5% in 1996 to 28.7% in 2004. This represents an increase from an estimated 18,500 to 31,000 admissions to all 240 adult, general critical care units in England, Wales and Northern Ireland. Hospital mortality for admissions with severe sepsis decreased from 48.3% in 1996 to 44.7% in 2004, but the total number of deaths increased from an estimated 9,000 to 14,000. The treated incidence of severe sepsis per 100,000 population rose from 46 in 1996 to 66 in 2003, with the associated number of hospital deaths per 100,000 population rising from 23 to 30.ConclusionThe population incidence of critical care admission with severe sepsis during the first 24 hours and associated hospital deaths are increasing. These baseline data provide essential information to those wishing to evaluate the introduction of the Surviving Sepsis Campaign care bundles in UK hospitals.

Community-acquired pneumonia on the intensive care unit: secondary analysis of 17,869 cases in the ICNARC Case Mix Programme Database

IntroductionThis paper describes the case mix, outcome and activity for admissions to intensive care units (ICUs) with community-acquired pneumonia (CAP).MethodsWe conducted a secondary analysis of a high quality clinical database, the Intensive Care National Audit & Research Centre (ICNARC) Case Mix Programme Database, of 301,871 admissions to 172 adult ICUs across England, Wales and Northern Ireland, 1995 to 2004. Cases of CAP were identified from pneumonia admissions excluding nosocomial pneumonias and the immuno-compromised. It was not possible to review data from the time of hospital admission; therefore, some patients who developed hospital-acquired/nosocomial pneumonia may have been included.ResultsWe identified 17,869 cases of CAP (5.9% of all ICU admissions). There was a 128% increase in admissions for CAP from 12.8 per unit to 29.2 per unit during the study period compared to only a 24% rise in total ICU admissions (p < 0.001). Eighty-five percent of admissions were from within the same hospital. Fifty-nine percent of cases were admitted to the ICU <2 days, 21.5% between 2 and 7 days, and 19.5% >7 days after hospital admission. Between 1995 and 1999 and 2000 and 2004 there was a rise in admissions from accident and emergency (14.8% to 16.8%; p < 0.001) and high dependency units (6.9% to 11.9%; p < 0.001) within the same hospital, those aged >74 (18.5 to 26.1%; p < 0.001), and mean APACHE II score (6.83 to 6.91; p < 0.001). There was a fall in past history of severe respiratory problems (8.7% to 6.4%; p < 0.001), renal replacement therapy (1.6% to 1.2%; p < 0.01), steroid treatment (3.4% to 2.8%; p < 0.05), sedation/paralysis (50.2% to 40.4%; p < 0.001), cardiopulmonary resuscitation prior to admission (7.5% to 5.5%; p < 0.001), and septic shock (7.3% to 6.6%; p < 0.001). ICU mortality was 34.9% and ultimate hospital mortality 49.4%. Mortality was 46.3% in those admitted to the ICU within 2 days of hospital admission rising to 50.4% in those admitted at 2 to 7 days and 57.6% in those admitted after 7 days following hospital admission.ConclusionCAP makes up a small, but important and rising, proportion of adult ICU admissions. Survival of over half of all cases vindicates the use of ICU facilities in CAP management. Nevertheless, overall mortality remains high, especially in those admitted later in their hospital stay.