The Multiple Organ Dysfunction Score as a descriptor of patient outcome in septic shock compared with two other scoring systems

Improvement of APACHE II score system for disease severity based on XGBoost algorithm

BACKGROUND

Prognostication is an essential tool for risk adjustment and decision making in the intensive care units (ICUs). In order to improve patient outcomes, we have been trying to develop a more effective model than Acute Physiology and Chronic Health Evaluation (APACHE) II to measure the severity of the patients in ICUs. The aim of the present study was to provide a mortality prediction model for ICUs patients, and to assess its performance relative to prediction based on the APACHE II scoring system.

METHODS

We used the Medical Information Mart for Intensive Care version III (MIMIC-III) database to build our model. After comparing the APACHE II with 6 typical machine learning (ML) methods, the best performing model was screened for external validation on anther independent dataset. Performance measures were calculated using cross-validation to avoid making biased assessments. The primary outcome was hospital mortality. Finally, we used TreeSHAP algorithm to explain the variable relationships in the extreme gradient boosting algorithm (XGBoost) model.

RESULTS

We picked out 14 variables with 24,777 cases to form our basic data set. When the variables were the same as those contained in the APACHE II, the accuracy of XGBoost (accuracy: 0.858) was higher than that of APACHE II (accuracy: 0.742) and other algorithms. In addition, it exhibited better calibration properties than other methods, the result in the area under the ROC curve (AUC: 0.76). we then expand the variable set by adding five new variables to improve the performance of our model. The accuracy, precision, recall, F1, and AUC of the XGBoost model increased, and were still higher than other models (0.866, 0.853, 0.870, 0.845, and 0.81, respectively). On the external validation dataset, the AUC was 0.79 and calibration properties were good.

CONCLUSIONS

As compared to conventional severity scores APACHE II, our XGBoost proposal offers improved performance for predicting hospital mortality in ICUs patients. Furthermore, the TreeSHAP can help to enhance the understanding of our model by providing detailed insights into the impact of different features on the disease risk. In sum, our model could help clinicians determine prognosis and improve patient outcomes.

Prognostic Value of Tissue Oxygen Saturation Using a Vascular Occlusion Test in Patients in the Early Phase of Multiorgan Dysfunction Syndrome

BACKGROUND

Multiple organ dysfunction syndrome (MODS) is a common disease pattern in intensive care units which is associated with an increased mortality. The aim of this study was to investigate whether a near-infrared spectroscopy (NIRS)-based noninvasive ischemia-reperfusion test (vascular occlusion test) using the parameter of tissue oxygen saturation (StO2) contains prognostic information for patients in the early phase of MODS.

METHODS

Within a period of 18 months between 2010 and 2012, 56 patients who newly developed MODS (≤24 h after diagnosis, Acute Physiology and Chronic Health Evaluation [APACHE] II score ≥20, subgroups: cardiogenic MODS [cMODS] and septic MODS [sMODS]) were included into the study. The StO2 was determined non-invasively in the area of the thenar muscles using a bedside NIRS device, InSpectra Tissue Spectrometer Model 650 (Hutchinson Technology Inc., Hutchinson, MN). The VOT was carried out by inflating a blood pressure cuff on the upper arm 30 mmHg above systolic blood pressure for 5 min. The parameters occlusion slope (OS) and recovery slope (RS) were recorded.

RESULTS

Fifteen patients with cMODS and 41 patients with sMODS were included in the study (age: 62.5 ± 14.4 years, 40 men and 16 women, APACHE II score: 34.6 ± 6.4). Twenty-eight-day-mortality was 55.4% (cMODS: 7 out of 15 patients, sMODS: 24 out of 41 patients). The measurement of StO2 while applying the VOT at baseline showed an OS of -11.7 ± 3.7%/min and an RS of 2.2 ± 1.5%/s. Survivors had significantly better values compared with non-survivors at baseline regarding OS (-12.8 ± 3.5%/min vs. -9.8 ± 3.4%/min; P = 0.016) and RS (2.6 ± 1.7%/s vs. 1.6 ± 1.0%/s; P = 0.022). Receiver-operating characteristic (ROC) curves show that the area under the curve (AUC) for OS was found to be significantly related to 28-day mortality (AUC: 0.7; 95% confidence interval [CI]: 0.56-0.85; P = 0.01). However, using both univariate and multivariate binary logistic regression models, RS was significantly associated with increased 28-day mortality (OR [univariate model]: 1.21 [95% CI: 1.1-1.8]; OR [multivariate model]: 1.23 [95% CI: 1.1-1.3]).

CONCLUSIONS

Impaired values of the VOT-parameters OS and RS are associated with an increased 28-day mortality in patients in the early phase of MODS.

Differential clinical benefits of continuous blood purification treatment in critically ill patients with variable APACHE II scores

The present study aimed to assess whether the Acute Physiology And Chronic Health Evaluation (APACHE) II score may be used to predict whether critically ill patients benefit from continuous blood purification (CBP) treatment. A total of 115 critically ill patients were retrospectively reviewed and grouped according to their baseline APACHE II scores. Each group was further divided into 2 groups based on whether they received CBP or not. At 72 h after CBP treatment, clinical indicators comprising the plasma levels of inflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-8, as well as endotoxin and procalcitonin (PCT), and severity scores (APACHE II, multiple organ dysfunction syndrome and systemic inflammatory response syndrome), were analyzed in all patients. It was observed that while CBP slightly reduced the severity scores in all patients, it significantly improved those in patients with an APACHE II score of 20-29 (P<0.05). Similarly, the plasma levels of TNF-α, IL-6, IL-8, endotoxin and PCT were significantly lower in patients receiving CBP than in those without CBP when the APACHE II score was 20-29 (P<0.05). Furthermore, CBP treatment significantly decreased the fatality rate and length of stay at the intensive care unit (ICU) for critically ill patients with an APACHE II score of 20-29 (P<0.05). In conclusion, CBP significantly decreases the inflammatory response, shortens the length of stay at the ICU and improves the prognosis for critically ill patients with an APACHE II score of 20-29 points. This observation suggests that the APACHE II score is an important clinical indicator to determine the potential benefit of CBP therapy in critically ill patients.

Optimal intensive care outcome prediction over time using machine learning

BACKGROUND

Prognostication is an essential tool for risk adjustment and decision making in the intensive care unit (ICU). Research into prognostication in ICU has so far been limited to data from admission or the first 24 hours. Most ICU admissions last longer than this, decisions are made throughout an admission, and some admissions are explicitly intended as time-limited prognostic trials. Despite this, temporal changes in prognostic ability during ICU admission has received little attention to date. Current predictive models, in the form of prognostic clinical tools, are typically derived from linear models and do not explicitly handle incremental information from trends. Machine learning (ML) allows predictive models to be developed which use non-linear predictors and complex interactions between variables, thus allowing incorporation of trends in measured variables over time; this has made it possible to investigate prognosis throughout an admission.

METHODS AND FINDINGS

This study uses ML to assess the predictability of ICU mortality as a function of time. Logistic regression against physiological data alone outperformed APACHE-II and demonstrated several important interactions including between lactate & noradrenaline dose, between lactate & MAP, and between age & MAP consistent with the current sepsis definitions. ML models consistently outperformed logistic regression with Deep Learning giving the best results. Predictive power was maximal on the second day and was further improved by incorporating trend data. Using a limited range of physiological and demographic variables, the best machine learning model on the first day showed an area under the receiver-operator characteristic curve (AUC) of 0.883 (σ = 0.008), compared to 0.846 (σ = 0.010) for a logistic regression from the same predictors and 0.836 (σ = 0.007) for a logistic regression based on the APACHE-II score. Adding information gathered on the second day of admission improved the maximum AUC to 0.895 (σ = 0.008). Beyond the second day, predictive ability declined.

CONCLUSION

This has implications for decision making in intensive care and provides a justification for time-limited trials of ICU therapy; the assessment of prognosis over more than one day may be a valuable strategy as new information on the second day helps to differentiate outcomes. New ML models based on trend data beyond the first day could greatly improve upon current risk stratification tools.

An observational study of incidence, risk factors & outcome of systemic inflammatory response & organ dysfunction following major trauma

Background & objectives:

Trauma is known to lead to systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS), which is often a cause of late deaths after injury. SIRS and MODS have been objectively measured using scoring systems. This prospective observational study was carried out in a tertiary care hospital in India to evaluate SIRS and MODS following trauma in terms of their incidence, the associated risk factors and the effect on the outcome.

Methods:

All adult patients with major life- and limb-threatening trauma were included. Patients who died within 24 h, those with severe head injury, known comorbidity, immunocompromised state, on immunosuppressants or pregnancy were excluded. SIRS and MODS scores were recorded after initial management (baseline score), on days 3 and 6 of admission. SIRS was defined as SIRS score of ≥2 and MODS was defined as MODS score of ≥1.

Results:

Two hundred patients were enrolled. SIRS was noted in 156 patients (78%). MODS was noted in 145 (72.5%) patients. Overall mortality was 39 (19.5%). Both SIRS and MODS scores were significantly associated with age >60 yr, blunt injury, (lower) revised trauma score hypotension on admission and (higher) injury severity score, but not with gender, pre-hospital time or operative treatment.

Interpretation & conclusions:

Both SIRS and MODS scores were associated with longer Intensive Care Unit (ICU) stay, more ICU interventions and higher mortality. Incidence of MODS was significantly higher in patients with SIRS. Both scores showed rising trend with time in non-survivors and a decreasing trend in survivors. The serial assessment of scores can help prognosticate outcome and also allocate appropriate critical care resources to patients with rising scores.

Predictors of Mortality in Septic Shock: Findings for 57 Patients Diagnosed on Admission to Emergency or within 24 hours of Admission to Intensive Care

Objective

To identify the risk factors that influence outcome for patients who are diagnosed with septic shock in the emergency department at presentation or within 24 hours after admission to intensive care unit.

Methods

A retrospective study of 57 adult patients with septic shock was conducted between March 1, 2006 and August 31, 2009.

Results

The patients were 23 males and 34 females with a median age of 67 years (20 to 92 years). Thirty-three (58%) of 57 patients died in hospital and 24 (42%) survived. Multivariate analysis identified low blood pH (OR <0.001; 95% CI <0.001-0.53) and low bicarbonate level (OR 0.81; 95% CI 0.70-0.95) at emergency department or intensive care unit admission as useful predictors of 3-day in-hospital mortality. Low blood pH (OR <0.001; 95% CI <0.001-0.05), low bicarbonate level (OR 0.75; 95% CIs 0.61-0.91), long duration of symptoms (OR 1.49; 95% CI 1.04-2.13), high MEDS score (OR 1.56; 95% CIs 1.06-2.30), and high SOFA score (OR 1.57; 95% CI 1.12-2.20) were risk factors for 14-day in-hospital mortality. Renal failure (OR 7.58; 95% CI 1.28-44.77), lower pulmonary tract infection (OR 3.58; 95% CI 1.10-11.58), high MEDS score (OR 1.42; 95% CI 1.05-1.93) and high APACHE II score (OR 1.34; 95% CI 1.13-1.60) were risk factors for 28-day in-hospital mortality.

Conclusions

Several factors signaling poor short-term outcome for this patient group are low blood pH, low serum bicarbonate level, longer duration of symptoms, lower respiratory tract infection and renal failure. MEDS and SOFA scores might be helpful in the ED to stratify patients with septic shock according to mortality risk.

Serum oxygen radical activity and total antioxidation capacity are related with severities of surgical patient with sepsis: Prospective pilot study

PURPOSE

The purpose of this pilot study was to evaluate the correlation between clinical severity and serum oxygen radical activity (ORA) and total antioxidation capacity (TAC) in critically ill surgical patients with sepsis.

MATERIALS AND METHODS

The prospective observational study was performed in surgical intensive care unit (SICU) patients with intra-abdominal sepsis. Serum ORA and TAC levels were measured using a spectrophotometry-based antioxidant assay machine. Serum selenium and zinc levels and plasma glutamine concentrations were also determined. Sequential organ failure assessment (SOFA) and multiple organ dysfunction (MOD) scores were calculated to evaluate the severity. Blood tests and severity scores were assessed on days 1, 3, and 7 in the SICU.

RESULTS

Twenty-seven patients were included. The mean APACHE II score was 22.4. The in-hospital mortality rate was 14.8%. Serum TAC levels correlated positively with SOFA and MOD scores on SICU days 1, 3 and 7, and serum ORA correlated negatively with SOFA and MOD scores on day 3. Serum zinc and selenium levels were lower than normal throughout the observation period. However, there was no significant relationship in clinical severity.

CONCLUSIONS

Serum TAC level may be a useful biomarker to predict severity of critically ill surgical patients with sepsis.

To develop a regional ICU mortality prediction model during the first 24 h of ICU admission utilizing MODS and NEMS with six other independent variables from the Critical Care Information System (CCIS) Ontario, Canada

Background

Intensive care unit (ICU) scoring systems or prediction models evolved to meet the desire of clinical and administrative leaders to assess the quality of care provided by their ICUs. The Critical Care Information System (CCIS) is province-wide data information for all Ontario, Canada level 3 and level 2 ICUs collected for this purpose. With the dataset, we developed a multivariable logistic regression ICU mortality prediction model during the first 24 h of ICU admission utilizing the explanatory variables including the two validated scores, Multiple Organs Dysfunctional Score (MODS) and Nine Equivalents Nursing Manpower Use Score (NEMS) followed by the variables age, sex, readmission to the ICU during the same hospital stay, admission diagnosis, source of admission, and the modified Charlson Co-morbidity Index (CCI) collected through the hospital health records.

Methods

This study is a single-center retrospective cohort review of 8822 records from the Critical Care Trauma Centre (CCTC) and Medical-Surgical Intensive Care Unit (MSICU) of London Health Sciences Centre (LHSC), Ontario, Canada between 1 Jan 2009 to 30 Nov 2012. Multivariable logistic regression on training dataset (n = 4321) was used to develop the model and validate by bootstrapping method on the testing dataset (n = 4501). Discrimination, calibration, and overall model performance were also assessed.

Results

The predictors significantly associated with ICU mortality included: age (p < 0.001), source of admission (p < 0.0001), ICU admitting diagnosis (p < 0.0001), MODS (p < 0.0001), and NEMS (p < 0.0001). The variables sex and modified CCI were not significantly associated with ICU mortality. The training dataset for the developed model has good discriminating ability between patients with high risk and those with low risk of mortality (c-statistic 0.787). The Hosmer and Lemeshow goodness-of-fit test has a strong correlation between the observed and expected ICU mortality (χ² = 5.48; p > 0.31). The overall optimism of the estimation between the training and testing data set ΔAUC = 0.003, indicating a stable prediction model.

Conclusions

This study demonstrates that CCIS data available after the first 24 h of ICU admission at LHSC can be used to create a robust mortality prediction model with acceptable fit statistic and internal validity for valid benchmarking and monitoring ICU performance.

Electronic supplementary material

The online version of this article (doi:10.1186/s40560-016-0143-6) contains supplementary material, which is available to authorized users.

Value of plasma neutrophil gelatinase-associated lipocalin in predicting the mortality of patients with sepsis at the emergency department

BACKGROUND

Sepsis is a major cause of morbidity and mortality in the emergency department. This study aimed to evaluate the assessment of severity of sepsis by and prognostic value of plasma neutrophil gelatinase-associated lipocalin (NGAL) compared with other widely used biological markers of inflammation in patients with sepsis.

METHODS

NGAL, procalcitonin, and C-reactive protein values were measured in 470 patients with suspected sepsis, and the Mortality in Emergency Department Sepsis (MEDS) score was obtained for all enrolled subjects, who were followed for up to 28days.

RESULTS

The median plasma NGAL value was increased with sepsis severity according to the MEDS score. The plasma NGAL value was higher in nonsurvivors than in survivors. The area under the receiver operating characteristic curve of NGAL (0.797) was greater than that of procalcitonin (0.599) and MEDS score (0.774) in predicting 28-day hospital mortality. Multivariable logistic regression found that the plasma NGAL value was an independent predictor for hospital mortality in patients with sepsis. The plasma NGAL values were positively correlated with C-reactive protein and procalcitonin levels, and MEDS scores.

CONCLUSIONS

Plasma NGAL is a valuable biological marker in the assessment of severity and prediction of prognosis of patients with sepsis in the emergency department.

Daily estimation of the severity of organ dysfunctions in critically ill children by using the PELOD-2 score

INTRODUCTION

Daily or serial evaluation of multiple organ dysfunction syndrome (MODS) scores may provide useful information. We aimed to validate the daily (d) PELOD-2 score using the set of seven days proposed with the previous version of the score.

METHODS

In all consecutive patients admitted to nine pediatric intensive care units (PICUs) we prospectively measured the dPELOD-2 score at day 1, 2, 5, 8, 12, 16, and 18. PICU mortality was used as the outcome dependent variable. The discriminant power of the dPELOD-2 scores was estimated using the area under the ROC curve and the calibration using the Hosmer-Lemeshow chi-square test. We used a logistic regression to investigate the relationship between the dPELOD-2 scores and outcome, and between the change in PELOD-2 score from day 1 and outcome.

RESULTS

We included 3669 patients (median age 15.5 months, mortality rate 6.1%, median length of PICU stay 3 days). Median dPELOD-2 scores were significantly higher in nonsurvivors than in survivors (p < 0.0001). The dPELOD-2 score was available at least at day 2 in 2057 patients: among the 796 patients without MODS on day 1, 186 (23.3%) acquired the syndrome during their PICU stay (mortality 4.9% vs. 0.3% among the 610 who did not; p < 0.0001). Among the 1261 patients with MODS on day 1, the syndrome worsened in 157 (12.4%) and remained unchanged or improved in 1104 (87.6%) (mortality 22.9% vs. 6.6%; p < 0.0001). The AUC of the dPELOD-2 scores ranged from 0.75 (95% CI: 0.67-0.83) to 0.89 (95% CI: 0.86-0.91). The calibration was good with a chi-square test between 13.5 (p = 0.06) and 0.9 (p = 0.99). The PELOD-2 score on day 1 was a significant prognostic factor; the serial evaluation of the change in the dPELOD-2 score from day1, adjusted for baseline value, demonstrated a significant odds ratio of death for each of the 7 days.

CONCLUSION

This study suggests that the progression of the severity of organ dysfunctions can be evaluated by measuring the dPELOD-2 score during a set of 7 days in PICU, providing useful information on outcome in critically ill children. Its external validation would be useful.

Consideration of additional factors in Sequential Organ Failure Assessment score

PURPOSE

The Sequential Organ Failure Assessment (SOFA) score, originally developed to assess organ failure status, is widely used as a prognostic indicator in intensive care unit patients. Additional prognostic factors, such as age and comorbidities, may complement the predictive performance of the SOFA.

METHODS

In total, 1049 consecutive patients were enrolled prospectively. SOFA and other admission-based intensive care unit scores were recorded during the first 24 hours. A complemented SOFA (cSOFA) score model was constructed by adding age and comorbidity scores to the original SOFA score, based on logistic regression analysis. The predictive performance was evaluated with regard to hospital mortality by receiver operating characteristics analysis. The Hosmer-Lemeshow goodness-of-fit test was used to assess calibration of the model, and leave-one-out cross-validation was performed.

RESULTS

The cSOFA score (maximum 30 points) was calculated as the SOFA score (24 points) + age score (2 points) + comorbidity score (4 points). The cSOFA score model showed satisfactory calibration and cross-validation performance. The AUC (95% CI) of the cSOFA score (0.812 [0.787-0.835]) was higher than the SOFA score (0.743 [0.715-0.769], P < .0001).

CONCLUSION

The performance of the SOFA score to predict hospital mortality can be improved by considering age and comorbidity factors.

Early alterations of B cells in patients with septic shock

Introduction

It has recently been proposed that B lymphocytes are involved in sepsis pathogenesis. The goal of this study is to investigate potential abnormalities in a subset distribution and activation of circulating B lymphocytes in patients with septic shock.

Methods

This observational prospective study was conducted in a medical-surgical ICU. All patients with septic shock were eligible for inclusion. B-cell phenotypes (CD19+CD69+, CD19+CD23+, CD19+CD5+, CD19+CD80, CD19+CD86+, CD19+CD40 and CD19+CD95+) were assessed by quantitative flow cytometry upon admission to the ICU and 3, 7, 14 and 28 d later.

Results

Fifty-two patients were included. Thirty-six healthy volunteers matched for age and sex were used as controls. The patients had lymphopenia that was maintained during 28 d of follow-up. In patients with septic shock who died, the percentage of CD19+CD23+ was lower during the 7 d of follow-up than it was in survival patients. Moreover, the percentage of CD80+ and CD95+ expression on B cells was higher in patients who died than in survivors. Receiver operating characteristic curve analysis showed that a CD19+CD23+ value of 64.6% at ICU admission enabled discrimination between survivors and nonsurvivors with a sensitivity of 90.9% and a specificity of 80.0% (P = 0.0001).

Conclusions

Patients with septic shock who survive and those who don't have different patterns of abnormalities in circulating B lymphocytes. At ICU admission, a low percentage of CD23+ and a high of CD80+ and CD95+ on B cells were associated with increased mortality of patients with septic shock. Moreover, a drop in circulating B cells persisted during 28 d of ICU follow-up.

Continuous multiorgan variability analysis to track severity of organ failure in critically ill patients

PURPOSE

The purpose of this study is to evaluate the utility of using continuous heart rate variability (HRV) and respiratory rate variability (RRV) monitoring for (a) tracking daily organ dysfunction in critically ill patients and (b) identifying patterns of variability changes during onset of shock and resolution of respiratory failure.

MATERIALS AND METHODS

Thirty-three critically ill patients experiencing respiratory and/or cardiac failure underwent continuous recording of their electrocardiogram and capnogram (CO2) waveforms from admission or intubation until discharge (maximum 14 days). HRV and RRV were computed in 5-minute overlapping windows, using Continuous Individualized Multi-organ Variability Analysis software. Multiple organ dysfunction scores were recorded daily. HRV and RRV trajectories were characterized during onset of shock and resolution of respiratory failure.

RESULTS

Both HRV and RRV decreased with increasing severity of multiple organ dysfunction scores for a variety of variability metrics. A decline in several measures of HRV and no decline in RRV were observed before onset of shock (n=6). In contrast, during resolution of respiratory failure, an increase in RRV was observed in patients who successfully passed extubation (n=12), with no change in RRV in those who subsequently failed extubation (n=2).

CONCLUSIONS

There is an association between reduced HRV and RRV and increasing organ dysfunction in critically ill patients. The significance of observing trends of decreasing HRV (with onset of shock) and increasing RRV (with resolution of respiratory failure) merits further investigation.

Prognostic categorization of intensive care septic patients

Sepsis is one of the leading worldwide causes of morbidity and mortality in critically-ill patients. Prediction of outcome in patients with sepsis requires repeated clinical interpretation of the patients’ conditions, clinical assessment of tissue hypoxia and the use of severity scoring systems, because the prognostic categorization accuracy of severity scoring indices alone, is relatively poor. Generally, such categorization depends on the severity of the septic state, ranging from systemic inflammatory response to septic shock. Now, there is no gold standard for the clinical assessment of tissue hypoxia which can be achieved by both global and regional oxygen extractabilities, added to prognostic pro-inflammatory mediators. Because the technology used to identify the genetic make-up of the human being is rapidly advancing, the structure of 30 000 genes which make-up the human DNA bank is now known. This would allow easy prognostic categorization of critically-ill patients including those suffering from sepsis. The present review spots lights on the main severity scoring systems used for outcome prediction in septic patients. For morbidity prediction, it discusses the Multiple Organ Dysfunction score, the sequential organ failure assessment score, and the logistic organ dysfunction score. For mortality/survival prediction, it discusses the Acute Physiology and Chronic Health Evaluation scores, the Therapeutic Intervention Scoring System, the Simplified acute physiology score and the Mortality Probability Models. An ideal severity scoring system for prognostic categorization of patients with systemic sepsis is far from being reached. Scoring systems should be used with repeated clinical interpretation of the patients’ conditions, and the assessment of tissue hypoxia in order to attain satisfactory discriminative performance and calibration power.

The logistic organ dysfunction score as a tool for making ethical decisions

PURPOSE

We examined whether the change of the logistic organ dysfunction score (LOD) between the first and the fourth day in the intensive care unit (ICU) could be predictive of death in the ICU. The LOD could then be used to help make decisions concerning therapeutic limitations (TL).

METHODS

One hundred fifty-four patients were included. Exclusion criteria were: discharge from the ICU or TL before the 72nd hr. Ninety-three patients remained for evaluation. The LOD was calculated on the day of admission (LOD1) and between the 72nd and 96th hr (LOD4). The DeltaLOD = LOD4-LOD1 index was calculated for survivors and non-survivors; sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated.

RESULTS

Sixteen patients died in the ICU, they had a higher DeltaLOD (0 vs -2; P = 0.0046) than the survivors. After logistic regression, a high DeltaLOD was associated with a higher risk of death in the ICU independent of the initial severity of disease. The PPV concerning death in the ICU was 0.66 for a DeltaLOD > or = 4 cut-off. The NPV was 0.89 for a cut-off of > or = 1.

CONCLUSION

DeltaLOD appears to be a predictor of death in the ICU, independent of the initial severity of disease. The PPV is not high enough to assist with making individual TL decisions. The NPV can help to identify patients at low risk of death. The DeltaLOD deserves to be evaluated in a population exhibiting greater severity of disease.

Daily assessment of organ dysfunction and survival in intensive care unit cardiac surgical patients

BACKGROUND

The purpose of this study was to develop a specific postoperative score for intensive care unit (ICU) cardiac surgical patients for assessment of organ dysfunction and survival.

METHODS

This prospective study consisted of all consecutive adult patients admitted after cardiac surgery to our ICU over a period of 3 years. Evaluation of variables was performed using the first year patients who stayed in the ICU for at least 24 hours. The reproducibility was then tested in two validation sets using all patients. Performance was assessed with the Hosmer-Lemeshow (chi2 statistics) goodness-of-fit test and receiver operating characteristic (ROC) curves and compared with the Acute Physiology and Chronic Health Evaluation (APACHE II) and Multiple Organ Dysfunction Score (MODS).

RESULTS

A total of 3,230 patients were admitted to the ICU after cardiac surgery. Mean chi2 values for the new score were 5.8 (APACHE II, 11.3; MODS, 9.7) for the construction set, 7.2 (APACHE II, 8.0; MODS, 4.5) for the validation set I, and 5.9 for the validation set II. The mean area under the ROC curve was 0.91 (APACHE II, 0.86; MODS, 0.84) for the new score in the construction set, 0.88 (APACHE II, 0.84; MODS, 0.84) in the validation set I, and 0.92 in the validation set II.

CONCLUSIONS

Our new 10-variable risk index performs very well, with calibration and discrimination very high, better than general severity systems; and it is an appropriate tool for daily risk stratification in ICU cardiac surgery patients. Thus, it may serve as an "expert system" for diagnosing organ failure, decision making, resource evaluation, and predicting mortality among ICU cardiac surgical patients.

Value of APACHE II, SOFA and CPIS Scores in Predicting Prognosis in Patients with Ventilator-Associated Pneumonia

BACKGROUND

Ventilator-associated pneumonia (VAP) is the most frequent infection with high mortality rates in intensive care units (ICUs) and the prediction of outcome is important in the decision-making process.

OBJECTIVE

To assess the value of the Acute Physiology and Chronic Health Evaluation II (APACHE II), Sequential Organ Failure Assessment (SOFA) and Clinical Pulmonary Infection Score (CPIS) in the prediction of mortality during VAP episodes in pulmonary patients.

METHODS

This study was a prospective observational cohort study. Sixty-three patients who were admitted to the ICU and developed VAP were included in the study consecutively. Clinical and laboratory data conforming to the APACHE II and SOFA scores were recorded on admission and APACHE II, SOFA and CPIS scores on the day of the diagnosis of VAP. The outcome measure was the ICU mortality. Logistic regression and receiver operating characteristic (ROC) curve analyses and the area under the curve (AUC) were used to estimate the predictive ability of the scoring systems.

RESULTS

Mortality rate was 54%. The mean APACHE II (21 +/- 6, 14 +/- 5; p = 0.001), SOFA (7 +/- 3, 4 +/- 2; p = 0.002) and CPIS (8 +/- 2, 7 +/- 3; p = 0.025) scores determined at the time of VAP diagnosis were significantly higher in nonsurvivors than in survivors. Discrimination was excellent for APACHE II (ROC AUC: 0.81; p = 0.001) and acceptable for SOFA (ROC AUC: 0.71; p = 0.005) scores. Of the three scores only APACHE II >16 was an independent predictor of the mortality (OR: 5; 95% CI: 1.3-18; p = 0.019) in the logistic regression analysis.

CONCLUSION

These results suggest that APACHE II determined at the time of VAP diagnosis may be useful in predicting mortality in the pulmonary ICU patient population who develops VAP.

Do we have reliable biochemical markers to predict the outcome of critical illness?

Current outcome prediction in critically ill patients relies on the art of clinical judgement and/or the science of prognostication using illness severity scores. The biochemical processes underlying critical illness have increasingly been unravelled. Several biochemical markers reflecting the process of inflammation, immune dysfunction, impaired tissue oxygenation and endocrine alterations have been evaluated for their predictive power in small subpopulations of critically ill patients. However, none of these parameters has been validated in large populations of unselected ICU patients as has been done for the illness severity and organ failure scores. A simple biochemical predictor of ICU mortality will probably remain elusive because the processes underlying critical illness are very complex and heterogeneous. Future prognostic models will need to be far more sophisticated.

Early changes in organ function predict eventual survival in severe sepsis*

OBJECTIVE

Early identification and treatment of severe sepsis can significantly reduce mortality rate. We hypothesized that a risk prediction model based on early (baseline to day 1 of study) response to standard care should be significantly related to 28-day survival.

DESIGN

Analysis of organ dysfunction data from two placebo-controlled severe sepsis trials (PROWESS and secretory phospholipase A2 inhibitor trials).

SETTING

Research laboratory.

PATIENTS

The placebo arms of two randomized, double-blind sepsis trials were combined (n = 1036). These patients met criteria for severe sepsis and received supportive standard intensive care and fluid resuscitation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Sequential Organ Failure Assessment (SOFA) scores were calculated daily using the most aberrant physiologic or laboratory variables. Baseline and post-baseline SOFA scores categorized as improved, unchanged, or worsened were used in regression analyses correlating organ dysfunction changes with 28-day mortality. Improvement in cardiovascular (p = .0010), renal (p < .0001), or respiratory (p = .0469) function from baseline to day 1 was significantly related to survival. Odds ratios (95% confidence intervals) associated with improved vs. worsened respiratory, cardiovascular, or renal function before start of day 1 were 0.56 (0.35-0.91), 0.33 (0.18-0.59), and 0.30 (0.17-0.52), respectively. Continued improvement in cardiovascular function before start of day 2 and start of day 3 was associated with further improvement in survival (p <. 0001), with odds ratios of 0.15 (0.06-0.39) and 0.11 (0.04-0.31) for patients who improved compared with those who worsened. No other organ system was retained in the model, and improvement beyond day 1 in any other organ function did not add to the model's predictive power.

CONCLUSIONS

These analyses suggest that outcomes for patients with severe sepsis are closely related to early (baseline to day 1 here) improvement, or lack thereof, in organ function. Also, clinical improvement on subsequent days may have little additional impact on the likelihood of survival.

Cumulative influence of organ dysfunctions and septic state on mortality of critically ill children

The interaction between sepsis and multiple organ dysfunction syndrome is poorly defined in children. We analyzed by Cox regression models the cumulative influence of organ dysfunctions, using the pediatric logistic organ dysfunction (PELOD) score, and septic state (systemic inflammatory response syndrome or sepsis, severe sepsis, and septic shock) on mortality of critically ill children. We included 593 children (mortality rate: 8.6%) from three pediatric intensive care units; 514 patients had at least a systemic inflammatory response syndrome and 269 had two or more organ dysfunctions. Hazard ratio of death significantly increased with the severity of organ dysfunction, as estimated by the PELOD score, and the worst diagnostic category of septic state. Each increase of one unit in the PELOD score multiplied the hazard ratio by 1.096 (p < 0.0001); hazard ratio of diagnostic category was 9.039 (p = 0.031) for systemic inflammatory response syndrome or sepsis, 18.797 (p = 0.007) for severe sepsis and 32.572 (p < 0.001) for septic shock. Cumulative hazard ratio of death = (hazard ratio of PELOD score) x (hazard ratio of diagnostic category). We conclude that there is a cumulative accrual of the risk of death both with an increasing severity of organ dysfunction and an increasing severity of the diagnostic category of septic state.

The Prediction of Adverse Maternal Outcomes in Preeclampsia

OBJECTIVES

(1) To evaluate whether clinical variables reflecting the multiorgan dysfunctions of preeclampsia can predict adverse maternal outcomes of preeclampsia; (2) to determine the usefulness of the mean platelet volume (MPV):platelet ratio as a novel measure of platelet consumption in predicting the severity of preeclampsia.

METHOD

A retrospective chart review was conducted of cases of preeclampsia seen in 3 tertiary level units from January 2001 to December 2001. Candidate predictors of adverse maternal outcome were gestational age (GA) on admission to hospital, blood pressure, proteinuria, urine output, uric acid, creatinine, aspartate transaminase (AST), lactate dehydrogenase, bilirubin, albumin, fraction of inspired oxygen:oxygen saturation (FIO2:SaO2) ratio, platelet count, MPV, MPV:platelet ratio, fibrinogen, and seizures. The combined adverse maternal outcomes included maternal death; 1 or more of hepatic failure, hematoma, or rupture; Glasgow coma scale <13; stroke; 2 or more seizures; cortical blindness; positive inotrope support; myocardial infarction; infusion of any third antihypertensive; dialysis; renal transplantation; > or =50% FIO2 for >1 hour; intubation; or transfusion of > or =10 units of blood products. Descriptive, univariable, and multivariable analyses were performed, with significance set at P < .05.

RESULTS

Of a total of 594 women with preeclampsia, 60 (10.1%) developed at least 1 element of the combined adverse outcome; 1 of these 60 women died. The most common outcomes were increased oxygen requirements, the use of a third infused antihypertensive, and transfusion >10 units. In women who developed an adverse outcome, GA and fibrinogen were lower, and total leukocyte count, creatinine, and AST were greater. Multivariable logistic regression revealed that admission GA (odds ratio [OR], 0.91), dipstick protein (OR, 1.31), and MPV:platelet ratio (OR, 391.0) independently predicted the outcome.

CONCLUSIONS

Several promising markers were identified: admission GA, dipstick proteinuria, and the MPV:platelet ratio. MPV:platelet ratio also showed promise as a marker of platelet consumption. A prospective study is required to develop a clinical prediction model for preeclampsia.

Increased glomerular permeability and pulmonary dysfunction following major surgery: correlation of microalbuminuria and PaO/FiO ratio

BACKGROUND

The aim of our trial was to evaluate the ability of microalbuminuria as an indicator of outcome and to investigate its relationship with the postoperative respiratory dysfunction in the initial postoperative period in a high-risk patient group.

METHODS

In our prospective, observational study patients were consecutively recruited following elective oesophagectomy, total gastrectomy, Whipple-resection of the pancreas and liver resection due to tumour removal. Microalbuminuria (expressed as urine albumin:creatinine ratio, M:Cr) was measured before (tp), and after surgery (t0, t6, t24, t48, t72). Multiple Organ Dysfunction Scores were monitored on ICU admission than daily (t1, t2, t3). For statistical analysis, Wilcoxon's rank-sum test, Mann-Whitney's U-test, receiver operating characteristic curve analysis and Spearman's rho test were used as appropriate.

RESULTS

One hundred and forty patients (118 survivors and 22 non-survivors) were recruited. Significantly higher Multiple Organ Dysfunction Scores were observed in non-survivors throughout the study period (P < 0.001). Microalbuminuria (Cr) increased significantly (P < 0.01) on admission to the ICU (t0) compared with the preoperative levels, but levels returned to normal within 6 h and remained so for the rest of the study. There was a significant difference between survivors and non-survivors at t0 (P < 0.01). However the ROC curve indicated that M:Cr is not a reliable descriptor of outcome. Comparison of Cr values with the PaO2/FiO2 ratio showed an inverse relationship on admission, which remained so for t24 and t48.

CONCLUSION

M:Cr measured on admission to the ICU was significantly higher in non-survivors than in survivors, and also showed an inverse relationship with the PaO2/FiO2 ratio following extended abdominal surgery. However, on admission, M:Cr did not discriminate survivors from non-survivors. Further studies are required to evaluate the prognostic value of this test for postoperative patients with risk of respiratory failure.

Validation of the multiple organ dysfunction (MOD) score in critically ill medical and surgical patients

OBJECTIVE

To validate the Multiple Organ Dysfunction (MOD) score externally.

DESIGN

Prospective observational cohort study.

SETTING

Mixed medical/surgical ICU in a tertiary referral university hospital.

PATIENTS AND PARTICIPANTS

Thousand eight hundred and nine patients admitted to ICU for more than 24 h over a 3-year period.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

The MOD score was calculated daily for all patients. The criterion validity of the individual organ scores, the maximal MOD score and the change in MOD score were assessed by examining the relationship between increasing scores and ICU mortality. Increased maximal MOD scores and each of the six individual organ scores, and change in MOD scores were associated with increased mortality.

CONCLUSIONS

Maximal and individual organ scores have criterion validity when tested in a different ICU from that in which the scores were derived, indicating that the scoring systems are reproducible. The association of change in MOD score with mortality indicates that the score is responsive. These data, combined with previous data establishing concept and content validity, indicate that the MOD score is a valid measure of multi-organ dysfunction.

Validation of the paediatric logistic organ dysfunction (PELOD) score: prospective, observational, multicentre study

BACKGROUND

Multiple organ dysfunction syndrome is more frequent than death in paediatric intensive care units. Estimation of the severity of this syndrome could be a useful additional outcome measure in clinical trials in such units. We aimed to validate the paediatric logistic organ dysfunction (PELOD) score and estimate its validity when recorded daily (dPELOD).

METHODS

We did a prospective, observational, multicentre cohort study in seven multidisciplinary, tertiary-care paediatric intensive care units of university-affiliated hospitals (two French, three Canadian, and two Swiss). We included 1806 consecutive patients (median age 24 months; IQR 5-90). PELOD score includes six organ dysfunctions and 12 variables and was recorded daily. For each variable, the most abnormal value each day and during the whole stay were used in calculating the dPELOD and PELOD scores, respectively. Outcome was vital status at discharge. We used Hosmer-Lemeshow goodness-of-fit tests to evaluate calibration and areas under receiver operating characteristic curve (AUC) to estimate discrimination.

FINDINGS

370 (21%) patients had no organ dysfunction, 471 (26%) had one, 457 (25%) had two, and 508 (28%) had three or more. Case fatality rate was 6.4% (115 deaths). PELOD score was significantly higher in non-survivors (mean 31.0 [SE 1.2]) than survivors (9.4 [0.2]; p<0.0001). Calibration (p=0.54) and discrimination (AUC=0.91, SE=0.01) of PELOD and dPELOD (p> or =0.39; AUC> or =0.79) scores were good.

INTERPRETATION

PELOD and dPELOD scores are valid outcome measures of the severity of multiple organ dysfunction syndrome in paediatric intensive care units; their use should significantly reduce the sample size required to complete clinical trials in critically ill children.

Fluconazole improves survival in septic shock: a randomized double-blind prospective study

OBJECTIVE

To demonstrate whether fluconazole reduces multiple organ failure and mortality in early septic shock (<24 hrs).

DESIGN

A prospective randomized double-blind study.

SETTING

A medical and surgical adult intensive care unit in a tertiary referral center.

PATIENTS

Values were obtained from 71 general adult intensive care unit patients.

INTERVENTIONS

During a 2.5-yr period, December 1998-June 2001, 71 patients with septic shock attributed to either nosocomial pneumonia (n = 37) or intra-abdominal sepsis (n = 34) were admitted to our intensive care unit and met the criteria of early septic shock and were entered into this study. All patients were randomized by our clinical pharmacist to receive daily either 200 mg of fluconazole in isotonic saline (fluconazole group = 32) or isotonic saline alone (placebo group = 39) intravenously during the course of their septic shock.

MEASUREMENTS AND MAIN RESULTS

All patients were closely monitored with pulmonary artery catheters and parameters to calculate daily organ dysfunction and Acute Physiology and Chronic Health Evaluation II scores. There was a highly significant increase in 30-day survival in the fluconazole-treated patients compared with the placebo patients (78% vs. 46%). However, fluconazole was found to be more effective in patients with septic shock attributed to intra-abdominal sepsis than to nosocomial pneumonia. Increased survival in the intra-abdominal sepsis clinical category was mirrored by a significantly lower number of organ failures in the treated group compared with the placebo group whereas the number of organ failures in the fluconazole group attributed to nosocomial pneumonia were not significantly increased compared with the control group. The septic shock state was considered in all cases to be attributed to bacterial and not to disseminated yeast infection with the exception of one patient in the control group who was admitted with candidemia. The mechanisms by which fluconazole exerts its protective effect against septic shock in patients is far from clear. However, fluconazole has been shown to enhance bactericidal activity of neutrophils and also to inhibit transmigration and adhesion of neutrophils in capillaries of distant organs.

CONCLUSIONS

The development of organ failure and mortality in septic shock was significantly reduced by fluconazole given intravenously. The mechanism of action of fluconazole in reducing multiple organ dysfunction in this group of patients may be attributed to the ability of fluconazole to increase recruitment, improve bactericidal activity of neutrophils, and to contain microorganisms locally.

Prognosis of hematologic malignancies does not predict intensive care unit mortality

OBJECTIVE

To evaluate the correlation between specific prognosis of hematologic malignancies on the one hand and intensive care unit and hospital mortality in critically ill patients with hematologic malignancies on the other hand.

DESIGN

Observational study during a 10-yr period.

SETTING

A 22-bed medical-surgical intensive care unit.

PATIENTS

A total of 84 consecutive patients with nonterminal hematologic malignancies with medical complications requiring intensive care.

INTERVENTIONS

None.

MEASUREMENTS

Demographic factors, acute physiology and organ dysfunction scores, microbiology, therapeutic support, and hematologic factors data on admission and during the intensive care unit stay were collected, together with mortality follow-up. Based on specific-disease prognostic factors and related published survival curves, the prognosis of hematologic malignancies was assessed and defined as good, intermediate, or poor according to a 3-yr survival probability of >50%, 20-50%, or <20%, respectively.

MAIN RESULTS

Prognosis of hematologic malignancies does not predict intensive care unit or hospital mortality and almost reaches significance for 6-mo mortality (53%, 71%, and 84% rate for patients with good, intermediate, and poor prognosis, respectively, p =.058), but it determines long-term survival (p =.008). Intensive care unit, hospital, and 6-mo overall mortality rates were 38%, 61%, and 75%, respectively. Using multivariate analysis, intensive care unit mortality was best predicted on admission by respiratory failure and fungal infection, whereas hospital mortality was predicted by the number of organ failures, the bone marrow transplant status, and the presence of fungal infection. The Acute Physiology and Chronic Health Evaluation II and the Simplified Acute Physiology Score II had no prognostic value, whereas the difference of the Multiple Organ Dysfunction Score between at the time of admission and at day 5 allowed quick prediction of hospital mortality. Diseases with the poorest 6-mo prognosis were acute myeloid leukemia and non-Hodgkin lymphoma. CONCLUSION The severity of the underlying hematologic malignancies does not influence intensive care unit or hospital mortality. Short-term prognosis is exclusively predicted by acute organ dysfunctions and by a pathogen's aggressiveness. Therefore, reluctance to admit patients with nonterminal hematologic malignancies to the intensive care unit based only on the prognosis of their underlying hematologic malignancy does not seem justified.

Calibration and discrimination by daily Logistic Organ Dysfunction scoring comparatively with daily Sequential Organ Failure Assessment scoring for predicting hospital mortality in critically ill patients

OBJECTIVE

The Logistic Organ Dysfunction (LOD) score has been proved effective in evaluating severity during the first day in an intensive care unit but has not been evaluated later. To evaluate attributable mortality related to nosocomial events, organ dysfunction scores that remain accurate throughout the intensive care unit stay are needed. The objective of this study was to evaluate how accurately daily LOD scoring predicts mortality comparatively with daily Sequential Organ Failure Assessment (SOFA) scoring.

DESIGN

Prospective multicenter study.

SETTING

Six intensive care units in France.

PATIENTS

A total of 1685 patients with intensive care unit stays longer than 48 hrs were included in this study (511 hospital deaths). Median age was 66 yrs, and median Simplified Acute Physiology Score II at admission was 38. For each patient, a senior physician recorded the variables needed to compute organ dysfunction scores daily throughout the intensive care unit stay.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

SOFA and LOD scores were computed daily during the first 7 days. Calibration was evaluated based on goodness-of-fit by the Hosmer-Lemeshow chi-square statistic (lower chi-square values and higher values indicate better fit) and discrimination based on the receiver operating characteristics (ROC) area under the curve (AUC; a ROC-AUC of 1 indicates faultless discrimination and a ROC-AUC of 0.5 indicates the effects of chance alone). Because calibration of both scores was poor at all time points ( p<.001), customization was performed using the total score (model 1) or separate introduction of each dysfunction (model 2). The performance of customized LOD and SOFA scores on a given day in predicting mortality was assessed in those patients who spent at least one more calendar day in the intensive care unit. The original LOD and SOFA scores had satisfactory ROC-AUC values (0.720 to 0.766). Internal consistency of both scores was acceptable ( p< 10(-4) for each organ dysfunction). After customization, the original scores calibrated well between days 1 and 7. Discrimination by both scores was better with model 2 (AUC-ROC, 0.729-0.784).

CONCLUSION

Daily LOD and SOFA scores showed good accuracy and internal consistency, and they could be used to adjust severity for events occurring in the intensive care unit.

Comparison of multiple organ dysfunction scores in the prediction of hospital mortality in the critically ill

OBJECTIVE

To compare the scales and predictive power for hospital mortality of three recent multiple organ dysfunction scores.

DESIGN

Prospective, observational, validation cohort study.

SETTING

A ten-bed medical-surgical intensive care unit in a Finnish tertiary care hospital.

PATIENTS

Among the 591 consecutive patients admitted, 520 patients who stayed >4 hrs were studied.

MEASUREMENTS AND MAIN RESULTS

Clinical and laboratory data were collected daily. Acute Physiology and Chronic Health Evaluation (APACHE) III, Multiple Organ Dysfunction Score, Logistic Organ Dysfunction score, and Sequential Organ Failure Assessment score all were calculated and compared for hospital mortality. The areas under receiver operating curves (SE) for day-1 scores were 0.825 (0.02) for APACHE III, 0.805 (0.02) for Logistic Organ Dysfunction, 0.776 (0.02) for SOFA, and 0.695 (0.02) for Multiple Organ Dysfunction Score in prediction of hospital mortality. The highest discriminative power was revealed with total maximum scores. No statistical differences existed between the total maximum scores (p values,.06 to.97). Calibration was good for all scores of day-1 multiple organ dysfunction scales and APACHE III by chi-square test (values between 10.14 and 5.42).

CONCLUSIONS

Discriminative power (ability to distinguish between patients who die and those who live) of day-1, of daily maximum, and especially of total maximum multiple organ dysfunction scores, were rather good, comparable with each other, and comparable with APACHE III in prediction of hospital mortality.

New issues in severity scoring: interfacing the ICU and evaluating it

Since the development of the first general outcome prediction models, these instruments have been widely used in the intensive care unit (ICU), both for patient evaluation and for ICU evaluation. Since some of these uses have been serious questioned, we assisted in the last years to the exploration of alternative paths for increasing the predictive power of the models and to enhance their applicability and utility in the real world. Part of these efforts focused on the exploration of more meaningful outcomes (clinical and non-clinical) with a strong tonic into the relation between outcomes and resources use. Also, since it is now widely recognized that the ICU is not an island, but it is integrated in a continuum of care, more and more efforts are being made to optimize and evaluate the interface between the ICU and the hospital, both at ICU admission and at ICU discharge. The objective of this review is to present and discuss, to the clinician working in the ICU, these emerging issues.

Monitoring organ function. Heart, liver, and kidney

No other part of critical care evaluation is more challenging than the monitoring of end-organ function. Defining the endpoints of resuscitation using organ function is complex and controversial. Although replete with opinions and data, the observation of cardiac, renal, and hepatic function and the technical ability to categorize organ performance is crucial to providing adequate intensive care resuscitation and monitoring.

Scoring systems for assessing organ dysfunction and survival

Sepsis is an ongoing disease process carrying a high risk of organ failure and death. Scoring systems to determine disease severity and risk of mortality may be useful in patient management and clinical trial enrollment, although the role of either type of score in the determination of admission or discharge criteria or in decisions relating to the continuation or withholding of treatment remains controversial. General scoring systems have been developed to quantify the severity of illness and the risk of mortality in ICU patients. Ideally, these should be customized before use in patients with septic shock, but in general noncustomized models are used, and this potential limitation should be acknowledged. Prognostic scores are remarkably reliable at predicting outcome in groups of patients and give an indication of severity of disease on admission, but they are unable to provide detail on how a patient is responding to treatment or on the disease progression. Organ function scores, however, can be assessed repeatedly and used to define a patient's progress. This approach can thus be used to evaluate individual patient care, to identify patients for enrollment in clinical trials or epidemiologic analyses, and to assess morbidity measures in clinical trials of new interventions. Organ dysfunction scores are just that, descriptors of organ dysfunction, and although high values correlate well with mortality, prognostication is not their prime aim; organ dysfunction scores and outcome prediction scores should rather be viewed as complementary systems in the description of ICU populations.