Hyperchloremia is associated with 30-day mortality in major trauma patients: a retrospective observational study

Fluid management in the septic peri-operative patient

PURPOSE

This review provides insight into recent clinical studies involving septic peri-operative patients and highlights gaps in understanding fluid management. The aim is to enhance the understanding of safe fluid resuscitation to optimize peri-operative outcomes and reduce complications.

RECENT FINDINGS

Recent research shows adverse surgical and clinical outcomes with both under- and over-hydration of peri-operative patients. The kinetic of intravenous fluids varies significantly during surgery, general anaesthesia, and sepsis with damage to endothelial glycocalyx (EG), which increases vascular permeability and interstitial oedema. Among clinical anaesthesia, neuraxial anaesthesia and sevoflurane have less effect on EG. Hypervolemia and the speed and volume of fluid infusion are also linked to EG shedding. Despite improvement in the antisepsis strategies, peri-operative sepsis is not uncommon. Fluid resuscitation is the cornerstone of sepsis management. However, overzealous fluid resuscitation is associated with increased mortality in patients with sepsis and septic shock. Personalized fluid resuscitation based on a careful assessment of intravascular volume status, dynamic haemodynamic variables and fluid tolerance appears to be a safe approach. Balanced solutions (BS) are preferred over 0.9% saline in patients with sepsis and septic shock due to a potential reduction in mortality, when exclusive BS are used and/or large volume of fluids are required for fluid resuscitation. Peri-operative goal-directed fluid therapy (GDFT) using dynamic haemodynamic variables remains an area of interest in reducing postoperative complications and can be considered for sepsis management (Supplementary Digital Content).

SUMMARY

Optimization of peri-operative fluid management is crucial for improving surgical outcomes and reducing postoperative complications in patients with sepsis. Individualized and GDFT using BS is the preferred approach for fluid resuscitation in septic peri-operative patients. Future research should evaluate the interaction between clinical anaesthesia and EG, its implications on fluid resuscitation, and the impact of GDFT in septic peri-operative patients.

Electrolyte Imbalance in Acute Traumatic Brain Injury: Insights from the First 24 h

BACKGROUND/OBJECTIVES

Electrolyte disturbances are common in patients with traumatic brain injury (TBI), particularly affecting sodium, potassium, chloride, and calcium levels. This study aims to provide insights into these disturbances within the first 24 h post-injury.

METHODS

We conducted a cross-sectional analysis of 50 TBI patients, excluding those with conditions affecting electrolyte balance. Electrolyte levels were measured, and correlations with demographic data, trauma mechanisms, imaging findings, and Glasgow Coma Scale (GCS) scores were analyzed.

RESULTS

The results indicated that chloride levels inversely correlated with GCS scores (ρ = -0.515; p = 0.002), suggesting that elevated chloride may indicate severe neurological impairment. Potassium levels were significantly associated with subdural hematoma (p = 0.032) and subarachnoid hemorrhage (p = 0.043), highlighting their potential as markers for severe brain injuries. No significant associations were found between sodium or calcium levels and the studied variables.

CONCLUSIONS

These findings underscore the importance of early monitoring of chloride and potassium levels in TBI patients to improve management and outcomes. Future research should focus on larger, multi-center studies to validate these findings and develop comprehensive guidelines for managing electrolyte imbalances in TBI patients.

Advancements in Trauma-Induced Acute Kidney Injury: Diagnostic and Therapeutic Innovations

Acute kidney injury following trauma impacts patient recovery critically, necessitating an integrated approach to emergency care and nephrology. This review aims to provide a comprehensive understanding of trauma-induced nephropathy, highlighting recent advancements in pathophysiological insights, diagnostic techniques, and strategic interventions. Our key findings emphasize the role of biomarkers, like Neutrophil Gelatinase-Associated Lipocalin and Liver Fatty Acid-Binding Protein, and imaging techniques, such as contrast-enhanced ultrasound, in early AKI detection. Preventive strategies, including aggressive fluid resuscitation, avoidance of nephrotoxic agents, and hemodynamic optimization, are essential for mitigating AKI progression. Integrating these approaches into trauma care frameworks aims to enhance patient outcomes and set a foundation for future research and clinical improvements.

Effect of hyperchloremia on mortality of pediatric trauma patients: a retrospective cohort study

BACKGROUND

Hyperchloremia is often encountered due to the frequent administration of intravenous fluids in critically ill patients with conditions such as shock or hypotension in the pediatric intensive care unit, and high serum levels of chloride are associated with poor clinical outcomes.

OBJECTIVES

This study aimed to determine the association between hyperchloremia and in-hospital mortality in pediatric patients with major trauma.

DESIGN AND SETTING

This retrospective cohort study was conducted at a tertiary university hospital in Turkey.

METHODS

Data were collected between March 2020 and April 2022. Patients aged 1 month to 18 years with major trauma who received intravenous fluids with a concentration > 0.9% sodium chloride were enrolled. Hyperchloremia was defined as a serum chloride level > 110 mmol/L. Clinical and laboratory data were compared between the survivors and nonsurvivors.

RESULTS

The mortality rate was 23% (n = 20). The incidence of hyperchloremia was significantly higher in nonsurvivors than in survivors (P = 0.05). In multivariate logistic analysis, hyperchloremia at 48 h was found to be an independent risk factor for mortality in pediatric patients with major trauma.

CONCLUSIONS

In pediatric patients with major trauma, hyperchloremia at 48-h postadmission was associated with 28-day mortality. This parameter might be a beneficial prognostic indicator.

Modified Nutrition Risk in the Critically ill score and mortality in critically ill patients with traumatic brain injury

BACKGROUND

Understanding the relationship between nutrition risk at admission to the intensive care unit (ICU) and the prognosis of patients with traumatic brain injury (TBI) may aid early recognition of high-risk patients.

METHODS

We extracted data from the Medical Information Mart for Intensive Care III and the electronic ICU Collaborative Research Databases. Using modified Nutrition Risk in the Critically ill score (mNUTRIC) within the first 24 h of ICU admission, 5153 patients were divided into three groups: low (≤1, n = 1765), moderate (2-4, n = 2574), and high (≥5, n = 814). The primary outcome was 28-day in-hospital mortality, and the secondary outcomes were 7-day in-hospital mortality, length of ICU stay, and duration of mechanical ventilation.

RESULTS

During the median follow-up time of 6.69 days, 647 deaths occurred in total. After adjustment for potential confounding factors, setting the low mNUTRIC group as a reference, the risk of 28-day mortality was increased in the high and moderate mNUTRIC groups (hazard ratio [HR]high vs low [95% CI]: 4.21 [2.70-6.58] and 2.84 [1.95-4.14], respectively). Similarly, high and moderate mNUTRIC scores are linked to a higher risk of 7-day mortality (PTrend  < 0.001) and a longer duration of mechanical ventilation (PTrend  < 0.001). The effect of mNUTRIC on mortality varied by serum glucose level (PInteraction  = 0.01). Lastly, those whose mNUTRIC scores deteriorated within the first 3 days have a 1.46 times greater risk of dying compared with patients with improved mNUTRIC scores.

CONCLUSIONS

Nutrition risk screening by mNUTRIC score at the time of admission to the ICU may improve mortality prediction.

Effect of Pre-Hospital Intravenous Fluids on Initial Metabolic Acid-Base Status in Trauma Patients: A Retrospective Cohort Study

Despite its known harmful effects, normal saline is still commonly used in the treatment of hypovolemia in polytrauma patients. Given the lack of pre-hospital research on this topic, the current study aims to assess the current practice of fluid administration during the pre-hospital phase of care and its effects on initial metabolic acid-base status in trauma patients. We extracted and completed data from patients recorded in the Lausanne University Hospital (CHUV) trauma registry between 2008 and 2019. Patients were selected according to their age, the availability of a blood gas analysis after arrival at the emergency room, data availability in the trauma registry, and the modality of arrival in the ED. The dominantly administered pre-hospital fluid was normal saline. No association between the type of fluid administered during the pre-hospital phase and the presence of hyperchloremic acidosis in the ED was observed.

Trauma-related electrolyte disturbances: From resuscitation to rhabdomyolysis

Traumatic injury results in drastic changes to a patient's normal physiology. The hormonal stress response, as well as some treatment strategies, lead to significant disruptions in electrolyte homeostasis that are important for clinicians to understand. In addition, advances in fluid resuscitation and modern transfusion practices have led to their own unique set of consequences, which we are just beginning to appreciate. Special attention is placed on rhabdomyolysis, as this distinct entity represents an extreme example of injury induced electrolyte derangements. This review describes the physiologic response to trauma and highlights some of the important electrolyte abnormalities that can be encountered while caring for the injured patient.

Increase in chloride from baseline is independently associated with mortality in intracerebral hemorrhage patients admitted to intensive care unit: A retrospective study

Background

Hyperchloremia is associated with increased mortality in critically ill patients. The objective of this study was to investigate the association between increased chloride levels and mortality outcomes in intracerebral hemorrhage (ICH) patients admitted to the intensive care unit (ICU).

Methods

We performed a retrospective study of all patients diagnosed with ICH and included in the Medical Information Mart for Intensive Care (MIMIC-Ⅲ) from 2001 to 2012. Inclusion criteria were the first diagnosis of ICH, ICU length of stay (LOS) over 72 h, and not receiving hypertonic saline treatment. Serum chloride perturbation within 72 h of admission was evaluated as a predictor of outcomes. The increase in chloride from baseline was dichotomized based on an increase in chloride in 72 h (≤5 mmol/L or >5 mmol/L). The primary outcome was 90-day mortality.

Results

A total of 376 patients (54.5% male, median age 70 years, interquartile range:58-79 years) were included. The overall 90-day mortality was 32.2% (n=121), in-hospital mortality was 25.8% (n=97), and Day 2 acute kidney injury (AKI) occurred in 29.0% (n=109) of patients. The prevalence of hyperchloremia on admission, during the first 72 h, and an increase in chloride (>5 mmol/L) were 8.8%, 39.4%, and 42.8%, respectively. After adjusting for confounders, the hazard ratio of increase in chloride (>5 mmol/L) was 1.66 (95% confidence interval:1.05-2.64, P=0.031). An increase in chloride (>5 mmol/L) was associated with a higher odds ratio for 90-day mortality in both the AKI and non-AKI groups.

Conclusions

An increase in chloride from baseline is common in adult patients with ICH admitted to ICU. The increase is significantly associated with elevated mortality. These results support the significance of diligently monitoring chloride levels in these patients.

Association of hyperchloremia with all-cause mortality in patients admitted to the surgical intensive care unit: a retrospective cohort study

Background

Serum chloride (Cl⁻) is one of the most essential extracellular anions. Based on emerging evidence obtained from patients with kidney or heart disease, hypochloremia has been recognized as an independent predictor of mortality. Nevertheless, excessive Cl⁻ can also cause death in severely ill patients. This study aimed to investigate the relationship between hyperchloremia and high mortality rate in patients admitted to the surgical intensive care unit (SICU).

Methods

We enrolled 2131 patients from the Multiparameter Intelligent Monitoring in Intensive Care III database version 1.4 (MIMIC-III v1.4) from 2001 to 2012. Selected SICU patients were more than 18 years old and survived more than 72 h. A serum Cl⁻ level ≥ 108 mEq/L was defined as hyperchloremia. Clinical and laboratory variables were compared between hyperchloremia (n = 664) at 72 h post-ICU admission and no hyperchloremia (n = 1467). The Locally Weighted Scatterplot Smoothing (Lowess) approach was utilized to investigate the correlation between serum Cl- and the thirty-day mortality rate. The Cox proportional-hazards model was employed to investigate whether serum chlorine at 72 h post-ICU admission was independently related to in-hospital, thirty-day and ninety-day mortality from all causes. Kaplan-Meier curve of thirty-day and ninety-day mortality and serum Cl⁻ at 72 h post-ICU admission was further constructed. Furthermore, we performed subgroup analyses to investigate the relationship between serum Cl⁻ at 72 h post-ICU admission and the thirty-day mortality from all causes.

Results

A J-shaped correlation was observed, indicating that hyperchloremia was linked to an elevated risk of thirty-day mortality from all causes. In the multivariate analyses, it was established that hyperchloremia remained a valuable predictor of in-hospital, thirty-day and ninety-day mortality from all causes; with adjusted hazard ratios (95% CIs) for hyperchloremia of 1.35 (1.02 ~ 1.77), 1.67 (1.28 ~ 2.19), and 1.39 (1.12 ~ 1.73), respectively. In subgroup analysis, we observed hyperchloremia had a significant interaction with AKI (P for interaction: 0.017), but there were no interactions with coronary heart disease, hypertension, and diabetes mellitus (P for interaction: 0.418, 0.157, 0.103, respectively).

Conclusion

Hyperchloremia at 72 h post-ICU admission and increasing serum Cl⁻ were associated with elevated mortality risk from all causes in severely ill SICU patients.

Subtyping Hyperchloremia among Hospitalized Patients by Machine Learning Consensus Clustering

Background and Objectives: Despite the association between hyperchloremia and adverse outcomes, mortality risks among patients with hyperchloremia have not consistently been observed among all studies with different patient populations with hyperchloremia. The objective of this study was to characterize hyperchloremic patients at hospital admission into clusters using an unsupervised machine learning approach and to evaluate the mortality risk among these distinct clusters. Materials and Methods: We performed consensus cluster analysis based on demographic information, principal diagnoses, comorbidities, and laboratory data among 11,394 hospitalized adult patients with admission serum chloride of >108 mEq/L. We calculated the standardized mean difference of each variable to identify each cluster's key features. We assessed the association of each hyperchloremia cluster with hospital and one-year mortality. Results: There were three distinct clusters of patients with admission hyperchloremia: 3237 (28%), 4059 (36%), and 4098 (36%) patients in clusters 1 through 3, respectively. Cluster 1 was characterized by higher serum chloride but lower serum sodium, bicarbonate, hemoglobin, and albumin. Cluster 2 was characterized by younger age, lower comorbidity score, lower serum chloride, and higher estimated glomerular filtration (eGFR), hemoglobin, and albumin. Cluster 3 was characterized by older age, higher comorbidity score, higher serum sodium, potassium, and lower eGFR. Compared with cluster 2, odds ratios for hospital mortality were 3.60 (95% CI 2.33-5.56) for cluster 1, and 4.83 (95% CI 3.21-7.28) for cluster 3, whereas hazard ratios for one-year mortality were 4.49 (95% CI 3.53-5.70) for cluster 1 and 6.96 (95% CI 5.56-8.72) for cluster 3. Conclusions: Our cluster analysis identified three clinically distinct phenotypes with differing mortality risks in hospitalized patients with admission hyperchloremia.

Association between the use of balanced fluids and outcomes in critically ill children: a before and after study

Background

Hyperchloremia and chloride load have been associated with worse clinical outcomes in critically ill patients. We sought to evaluate the electrolyte profile and clinical outcomes associated with a unit-wide transition from saline to balanced fluids for resuscitation and maintenance fluids in a pediatric intensive care unit (PICU).

Methods

A before and after analysis of all patients admitted to the PICU in a large, urban, academic hospital between August 2018 and March 2020. The transition from the use of saline to the use of balanced fluids for both resuscitation and maintenance fluid as standard care occurred in June 2019. The primary outcome was day 3 acute kidney injury (AKI). The secondary outcomes included mortality, ventilator-free days (VFDs), need for renal replacement therapy (RRT), hospital length of stay (LOS), and electrolyte abnormalities.

Results

Overall, 2863 patients (47% female) with a day 3 AKI rate of 12.9% (n = 130) and a mortality rate of 2.8% (n = 79) were included. After adjusting for confounders (age, PRISM III, mechanical ventilation, and immunocompromised state, septic shock), there were no significant differences in the odds of day 3 AKI (pre 13%, post 12.5%; adjusted odds ratio [aOR] 0.96, 95%CI 0.65–1.42). There were no differences in the secondary outcomes. The post-intervention period had fewer patients with hyperchloremia (pre 15.5% vs. post 10.4%, p =  < 0.0001) and hyperkalemia (pre 3.2% vs. post 1.4%, p = 0.02) and more patients with hypochloremia (pre 9.5% vs. post 14.4%, p =  < 0.0001) and hypokalemia (pre 38.2% vs. post 47.2%, p =  < 0.0001). In reference to the normochloremic cohort, the hypochloremic cohort had an increase in day 3 AKI, need for RRT, hyperchloremia, and hyperkalemia, and a decrease in hypokalemia; and the hyperchloremic cohort had an increase in VFD and a decrease in hospital LOS.

Conclusions

Following a unit-wide implementation of balanced fluids as standard care, there were no differences in rates of day 3 AKI or other clinical outcomes. However, there were lower rates of hyperkalemia and hyperchloremia and higher rates of hypokalemia and hypochloremia. Further evaluation of the effect of balanced fluids and the clinical significance of electrolyte abnormalities in critically ill children is needed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03705-3.

High Chloride Burden and Clinical Outcomes in Critically Ill Patients With Large Hemispheric Infarction

Background: In general, disease severity has been found to be associated with abnormal chloride levels in critically ill patients, but hyperchloremia is associated with mixed results regarding patient-centered clinical outcomes. We aimed to investigate the impact of maximum serum chloride concentration on the clinical outcomes of critically ill patients with large hemispheric infarction (LHI).

Methods: We conducted a retrospective observational cohort study using prospective institutional neurocritical care registry data from 2013 to 2018. Patients with LHIs involving over two-thirds of middle cerebral artery territory, with or without infarction of other vascular territories, and a baseline National Institutes of Health Stroke Scale score of ≥13 were assessed. Those with a baseline creatinine clearance of <15 mL/min and required neurocritical care for <72 h were excluded. Primary outcome was in-hospital mortality. Secondary outcomes included 3-month mortality and acute kidney injury (AKI) occurrence. Outcomes were compared to different maximum serum chloride levels (5 mmol/L increases) during the entire hospitalization period using multivariable logistic regression analyses.

Results: Of 90 patients, 20 (22.2%) died in-hospital. Patients who died in-hospital had significantly higher maximum serum chloride levels than did those who survived up to hospital discharge (139.7 ± 8.1 vs. 119.1 ± 10.4 mmol/L; p < 0.001). After adjusting for age, sex, and Glasgow coma scale score, each 5-mmol/L increase in maximum serum chloride concentration was independently associated with an increased risk of in-hospital mortality (adjusted odds ratio (aOR), 4.34; 95% confidence interval [CI], 1.98–9.50; p < 0.001). Maximum serum chloride level was also an independent risk factor for 3-month mortality (aOR, 1.99 [per 5 mmol/L increase]; 95% CI, 1.42–2.79; p < 0.001) and AKI occurrence (aOR, 1.57 [per 5 mmol/L increase]; 95% CI, 1.18–2.08; p = 0.002).

Conclusions: High maximum serum chloride concentrations were associated with poor clinical outcomes in critically ill patients with LHI. This study highlights the importance of monitoring serum chloride levels and avoiding hyperchloremia in this patient population.

The Association Between Variability in Electrolytes and the In-Hospital Mortality in Critically Ill Children in Pediatric Intensive Care Units

Objective: This study aimed to explore the association between the variability in electrolytes and the in-hospital mortality in critically ill children admitted into intensive care units (ICUs). Design: This is a retrospective case-control study. Setting and Participants: Total of 11,245 children have been admitted to ICUs of Children's Hospital of Zhejiang University from 2010 to 2018. Methods: The coefficient of variation (CV), standard deviation (SD), and variability independent of the mean (VIM) were calculated as variability indices. High variability was defined as having values in the highest quartile for each parameter. Age, sex, diagnoses of disease, and surgical treatment were adjusted in the multivariable-adjusted logistic regression model. Results: A total of 11,245 children were included, and 660 patients died in the hospital. The median (P25, P75) potassium, sodium, and chloride of all patients were 3.8 (3.58, 4.09), 136.83 (135.11, 138.60), and 108.67 (105.71, 111.17), respectively. U-shaped relationships between the mean, lowest, and highest levels of potassium, sodium, and chloride and the in-hospital mortality were observed. The lowest mortality was noted when serum potassium, sodium, and chloride were between ~3.5 and 5.0, 135 and 145, and 105 and 115 mmol/l, respectively. The areas under the curve (AUCs) of three indices of variability in electrolytes were larger than those of the mean and lowest levels of electrolytes in predicting the in-hospital mortality. In the multivariable-adjusted model, the odds ratios and 95% confidence interval (CI) of the in-hospital mortality were 3.14 (2.44-4.04) for one parameter, 5.85 (4.54-7.53) for two parameters, and 10.32 (7.81-13.64) for three parameters compared with subjects having no parameters of high variability measured as the CV. The results were consistent when the variability was determined using the SD and VIM (all P for trend <0.001). Consistent results were noted in various subgroup analyses. Conclusions: This study showed that individuals with higher variability of each parameter were related with higher risk of in-hospital mortality. There was a linear association between the number of high variability parameters and the in-hospital mortality. The variability of electrolytes might be a good predictor for in-hospital mortality of children in ICUs.

Association of Hyperchloremia and Acute Kidney Injury in Patients With Traumatic Brain Injury

Introduction:

Hypertonic saline is often used to treat patients with traumatic brain injury. It carries the undesired side effect of hyperchloremia, which has been linked to acute kidney injury (AKI). We sought to evaluate the relationship of hyperchloremia and AKI in this population and whether the absolute exposure to hyperchloremia, including maximal hyperchloremia and duration of hyperchloremia were associated with AKI.

Methods:

A retrospective study of severe traumatic brain injury patients who received hypertonic saline at a single academic institution. Demographics, head abbreviated injury scale, development of hyperchloremia (Cl ≥ 115), duration of hyperchloremia, highest chloride level, duration of hypertonic saline use, admission GFR, and administration of nephrotoxic medications were abstracted. The outcome of interest was the association between renal function and hyperchloremia.

Results:

A total of 123 patients were included in the study. Multivariable logistic regression analysis demonstrated that only duration of hyperchloremia ( p = 0.014) and GFR on admission ( p = 0.004) were independently associated with development of AKI. The number of days of hypertonic saline infusion ( p = 0.79) without the persistence of hyperchloremia and highest serum chloride levels ( p = 0.23) were not predictive of AKI development.

Discussion:

In patients with traumatic brain injury, admission GFR and prolonged hyperchloremia rather than the highest chloride level or the duration of hypertonic saline infusion were associated with the development of AKI.

Intravenous Fluid Management in Critically Ill Adults: A Review

TOPIC

This article reviews the management of intravenous fluids and the evaluation of volume status in critically ill adults.

CLINICAL RELEVANCE

Intravenous fluid administration is one of the most common interventions in the intensive care unit. Critically ill patients have dynamic fluid requirements, making the management of fluid therapy challenging. New literature suggests that balanced salt solutions may be preferred in some patient populations.

PURPOSE OF PAPER

The bedside critical care nurse must understand the properties of various intravenous fluids and their corresponding impact on human physiology. The nurse's clinical and laboratory assessments of each patient help define the goals of fluid therapy, which will in turn be used to determine the optimal patient-specific selection and dose of fluid for administration. Nurses serve a vital role in monitoring the safety and efficacy of intravenous fluid therapy. Although this intervention can be lifesaving, inappropriate use of fluids has the potential to yield detrimental effects.

CONTENT COVERED

This article discusses fluid physiology and the goals of intravenous fluid therapy, compares the types of intravenous fluids (isotonic crystalloids, including 0.9% sodium chloride and balanced salt solutions; hypotonic and hypertonic crystalloids; and colloids) and their adverse effects and impact on hemodynamics, and describes the critical care nurse's essential role in selecting and monitoring intravenous fluid therapy.

Association of Chloride Ion and Sodium-Chloride Difference With Acute Kidney Injury and Mortality in Critically Ill Patients

Objectives

Derangements of chloride ion concentration ([Cl^-]) have been shown to be associated with acute kidney injury and other adverse outcomes. For a physicochemical approach, however, chloride ion concentration should be considered with sodium ion concentration. This study aimed to examine the association of chloride ion concentration and the main strong ion difference (difference between sodium ion concentration and chloride ion concentration) during the first 24 hours after admission into ICU with the development of acute kidney injury and mortality.

Design

Retrospective analyses using the eICU Collaborative Research Database.

Setting

ICUs in 208 hospitals across the United States between 2014 and 2015.

Patients

Critically ill patients who were admitted into the ICU.

Interventions

None.

Measurements and Main Results

A total of 34,801 patients records were analyzed. A multivariable logistic regression analysis for the development of acute kidney injury within 7 days of ICU admission shows that, compared with main strong iron difference 32-34 mEq/as a reference, there were significantly high odds for the development of acute kidney injury in nearly all groups with main strong iron difference more than 34 mEq/L (main strong iron difference = 34-36 mEq/L, odds ratio = 1.17, p = 0.02; main strong iron difference = 38-40 mEq/L, odds ratio = 1.40, p < 0.001; main strong iron difference = 40-42 mEq/L, odds ratio = 1.46, p = 0.001; main strong iron difference > 42 mEq/L, odds ratio = 1.56, p < 0.001). With chloride ion concentration 104-106 mEq/L as a reference, the odds for acute kidney injury were significantly higher only in chloride ion concentration less than or equal to 94 mEq/L and chloride ion concentration 98-100 mEq/L groups. Analyses conducted using inverse probability weighting showed significantly greater odds for ICU mortality in all groups with main strong iron difference greater than 34mEq/L other than the 36-38mEq/L group, as well as in the less than 26-mEq/L group.

Conclusions

Main strong iron difference measured on ICU presentation to the ICU predicts acute kidney injury within 7 days, with low and, in particular, high values representing increased risk. The association between the chloride levels and acute kidney injury is statistically insignificant in models incorporating main strong iron difference, suggesting main strong iron difference is a better predictive marker than chloride on ICU admission.

Pediatric Mortality and Acute Kidney Injury Are Associated with Chloride Abnormalities in Intensive Care Units in the United States: A Multicenter Observational Study

Our objective was to determine in children in the intensive care unit (ICU) the incidence of hyperchloremia (>110 mmol/L) and hypochloremia (<98 mmol/L), the association of diagnoses with chloride abnormalities, and the associations of mortality and acute kidney injury (AKI) with chloride abnormalities. We analyzed the initial, maximum, and minimum chloride measurements of 14,684 children in the ICU with ≥1 chloride measurement in the Health Facts database between 2009 and 2016. For hyperchloremia and hypochloremia compared with normochloremia, mortality rates increased three to fivefold and AKI rates increased 1.5 to threefold. The highest mortality rate (7.7%; n = 95/1,234) occurred with hyperchloremia in the minimum chloride measurement group and the highest AKI rate (7.7%; n = 72/930) occurred with hypochloremia in the initial chloride measurement group. The most common diagnostic categories associated with chloride abnormalities were injury and poisoning; respiratory; central nervous system; infectious and parasitic diseases; and endocrine, nutritional, metabolic, and immunity disorders. Controlled for race, gender, age, and diagnostic categories, mortality odds ratios, and AKI odds ratios were significantly higher for hyperchloremia and hypochloremia compared with normochloremia. In conclusion, hyperchloremia and hypochloremia are independently associated with mortality and AKI in children in the ICU.

Hospital-Acquired Serum Chloride Derangements and Associated In-Hospital Mortality

Background: We aimed to describe the incidence of hospital-acquired dyschloremia and its association with in-hospital mortality in general hospitalized patients. Methods: All hospitalized patients from 2009 to 2013 who had normal admission serum chloride and at least two serum chloride measurements in the hospital were studied. The normal range of serum chloride was defined as 100–108 mmol/L. Hospital serum chloride levels were grouped based on the occurrence of hospital-acquired hypochloremia and hyperchloremia. The association of hospital-acquired hypochloremia and hyperchloremia with in-hospital mortality was analyzed using logistic regression. Results: Among the total of 39,298 hospitalized patients, 59% had persistently normal hospital serum chloride levels, 21% had hospital-acquired hypochloremia only, 15% had hospital-acquired hyperchloremia only, and 5% had both hypochloremia and hyperchloremia. Compared with patients with persistently normal hospital serum chloride levels, hospital-acquired hyperchloremia only (odds ratio or OR 2.84; p < 0.001) and both hospital-acquired hypochloremia and hyperchloremia (OR 1.72; p = 0.004) were associated with increased in-hospital mortality, whereas hospital-acquired hypochloremia only was not (OR 0.91; p = 0.54). Conclusions: Approximately 40% of hospitalized patients developed serum chloride derangements. Hospital-acquired hyperchloremia, but not hypochloremia, was associated with increased in-hospital mortality.

Plasma-Lyte 148 and Plasma-Lyte 148 + 5% glucose compatibility with commonly used critical care drugs

PURPOSE

Plasma-Lyte is a balanced, crystalloid intravenous fluid which has been shown to avoid the hyperchloremic metabolic acidosis associated with 0.9% sodium chloride. Data on physical, pH and chemical compatibility with other medicines are essential.

METHODS

The compatibility of adrenaline, dobutamine, dopamine, furosemide, midazolam, morphine and milrinone with Plasma-Lyte 148 (PLA) and Plasma-Lyte 148 with 5% glucose (PLA-G) was investigated. Control solutions were 0.9% sodium chloride and 5% glucose. Chemical stability was defined as < 5% concentration change with high-performance liquid chromatography (HPLC). Physical compatibility was assessed by checking for colour changes and precipitate formation. The pH of the admixtures was considered acceptable if between 5 and 9 at all time points. Six repeats were carried out for HPLC, 2 for physical compatibility checks and pH measurements, with all admixtures being tested at 0, 2 and 24 h after mixing.

RESULTS

All combinations were found to be chemically stable at 0, 2 and 24 h apart from furosemide with PLA-G at 24 h and midazolam with PLA or PLA-G at both 2 and 24 h. Only midazolam was physically incompatible when mixed with both Plasma-Lyte solutions. The pH remained stable in all admixtures, although not all pH values recorded were within the range of 5-9.

CONCLUSION

All drugs excluding furosemide and midazolam were shown to be chemically, physically and pH stable at the tested concentrations when diluted with PLA and PLA-G.

Serum Chloride Levels at Hospital Discharge and One-Year Mortality among Hospitalized Patients

This study aimed to assess the one-year mortality risk based on discharge serum chloride among the hospital survivors. We analyzed a cohort of adult hospital survivors at a tertiary referral hospital from 2011 through 2013. We categorized discharge serum chloride; ≤96, 97–99, 100–102, 103–105, 106–108, and ≥109 mmoL/L. We performed Cox proportional hazard analysis to assess the association of discharge serum chloride with one-year mortality after hospital discharge, using discharge serum chloride of 103–105 mmoL/L as the reference group. Of 56,907 eligible patients, 9%, 14%, 26%, 28%, 16%, and 7% of patients had discharge serum chloride of ≤96, 97–99, 100–102, 103–105, 106–108, and ≥109 mmoL/L, respectively. We observed a U-shaped association of discharge serum chloride with one-year mortality, with nadir mortality associated with discharge serum chloride of 103–105 mmoL/L. When adjusting for potential confounders, including discharge serum sodium, discharge serum bicarbonate, and admission serum chloride, one-year mortality was significantly higher in both discharge serum chloride ≤99 hazard ratio (HR): 1.45 and 1.94 for discharge serum chloride of 97–99 and ≤96 mmoL/L, respectively; p < 0.001) and ≥109 mmoL/L (HR: 1.41; p < 0.001), compared with discharge serum chloride of 103–105 mmoL/L. The mortality risk did not differ when discharge serum chloride ranged from 100 to 108 mmoL/L. Of note, there was a significant interaction between admission and discharge serum chloride on one-year mortality. Serum chloride at hospital discharge in the optimal range of 100–108 mmoL/L predicted the favorable survival outcome. Both hypochloremia and hyperchloremia at discharge were associated with increased risk of one-year mortality, independent of admission serum chloride, discharge serum sodium, and serum bicarbonate.

An Association Between Hyperchloremia and Acute Kidney Injury in Patients With Acute Ischemic Stroke

Background and Purpose

While an association between hyperchloremia and worse outcomes, such as acute kidney injury and increased mortality, has been demonstrated in hemorrhagic stroke, it is unclear whether the same relationship exists after acute ischemic stroke. This study aims to determine the relationship between moderate hyperchloremia (serum chloride ≥115 mmol/L) and acute kidney injury in patients with ischemic stroke.

Methods

This is a multicenter, retrospective, propensity-matched cohort study of adults admitted for acute ischemic stroke. The primary objective was to determine the relationship between moderate hyperchloremia and acute kidney injury, as defined by the Acute Kidney Injury Network criteria. Secondary objectives included mortality and hospital length of stay.

Results

A total of 407 patients were included in the unmatched cohort (332 nonhyperchloremia and 75 hyperchloremia) and 114 patients (57 in each group) were matched based upon propensity scores. In the matched cohort, hyperchloremia was associated with an increased risk of acute kidney injury (relative risk 1.91 [95% confidence interval 1.01-3.59]) and a longer hospital length of stay (16 vs 12 days; P = .03). Mortality was higher in the hyperchloremia group (19.3% vs 10.5%, P = .19), but this did not reach statistical significance.

Conclusions

In this study, hyperchloremia after ischemic stroke was associated with increased rates of acute kidney injury and longer hospital length of stay. Further research is needed to determine which interventions may increase chloride levels in patients with acute ischemic stroke and the association between hyperchloremia and clinical outcomes.

Hyperchloremia and acute kidney injury: a retrospective observational cohort study on a general mixed medical-surgical not ICU-hospitalized population

The aim of this observational retrospective cohort study was to analyze the association between hyperchloremia and serum chloride variation with in-hospital acute kidney injury (AKI) and mortality in a general, no-ICU hospitalized population. We performed a retrospective study on inpatient population admitted to Fondazione Policlinico Universitario A. Gemelli IRCCS between January 2010 and December 2014 with inclusion of adult patients with at least two values available for chloride, sodium and creatinine. Hyperchloremia was defined as serum chloride concentration ≥ 108 mmol/L (moderate hyperchloremia: chloremia between 108-110 mmol/L, severe hyperchloremia: chloremia > 110 mmol/L). According to the time of onset of the electrolyte disturbance, hyperchloremia was then classified as hospital acquired (HA) and community acquired (CA). In patients with HA-hyperchloremia, chloride variation (ΔCl) was calculated. In-hospital AKI was defined according to creatinine kinetics criteria occurring 48 h after hospital admission. Logistic regression analysis was used to evaluate the association between the exposures of interest and in-hospital AKI and mortality. A total of 24,912 hospital admissions met the inclusion criteria. Regression analyses showed that only severe HA-hyperchloremia was associated with increased risk of in-hospital AKI [odds ratio (OR) 2.60, 95% confidence interval (CI) 1.58, 4.30, p value < 0.001] and death (OR 3.89, 95% CI 2.11, 7.18, p value < 0.001). With increasing ΔCl, the OR of in-hospital AKI increased progressively (p value for trend = 0.005). In conclusion, severe hyperchloremia is an independent predictor for in-hospital AKI and mortality; HA-hyperchloremia is more detrimental for patient outcome; higher ΔCl from hospital admission is associated with increased risk of AKI.

Hyperchloremia, not Concomitant Hypernatremia, Independently Predicts Early Mortality in Critically Ill Moderate-Severe Traumatic Brain Injury Patients

BACKGROUND

Hypernatremia has been associated with mortality in neurocritically ill patients, with and without traumatic brain injury (TBI). These studies, however, lack concomitant adjustment for hyperchloremia as a physiologically co-occurring finding despite the associations with hyperchloremia and worse outcomes after trauma, sepsis, and intracerebral hemorrhage. The objective of our study was to examine the association of concomitant hypernatremia and hyperchloremia with in-hospital mortality in moderate-severe TBI (msTBI) patients.

METHODS

We retrospectively analyzed prospectively collected data from the OPTIMISM-study and included all msTBI patients consecutively enrolled between 11/2009 and 1/2017. Time-weighted average (TWA) sodium and chloride values were calculated for all patients to examine the unadjusted mortality rates associated with the burden of hypernatremia and hyperchloremia over the entire duration of the intensive care unit stay. Multivariable logistic regression modeling predicting in-hospital mortality adjusted for validated confounders of msTBI mortality was applied to evaluate the concomitant effects of hypernatremia and hyperchloremia. Internal bootstrap validation was performed.

RESULTS

Of the 458 patients included for analysis, 202 (44%) died during the index hospitalization. Fifty-five patients (12%) were excluded due to missing data. Unadjusted mortality rates were nearly linearly increasing for both TWA sodium and TWA chloride, and were highest for patients with a TWA sodium > 160 mmol/L (100% mortality) and TWA chloride > 125 mmol/L (94% mortality). When evaluated separately in the multivariable analysis, TWA sodium (per 10 mmol/L change: adjusted OR 4.0 [95% CI 2.1-7.5]) and TWA chloride (per 10 mmol/L change: adjusted OR 3.9 [95% CI 2.2-7.1]) independently predicted in-hospital mortality. When evaluated in combination, TWA chloride remained independently associated with in-hospital mortality (per 10 mmol/L change: adjusted OR 2.9 [95% CI 1.1-7.8]), while this association was no longer observed with TWA sodium values (per 10 mmol/L change: adjusted OR 1.5 [95% CI 0.51-4.4]).

CONCLUSIONS

When concomitantly adjusting for the burden of hyperchloremia and hypernatremia, only hyperchloremia was independently associated with in-hospital mortality in our msTBI cohort. Pending validation, our findings may provide the rationale for future studies with targeted interventions to reduce hyperchloremia and improve outcomes in msTBI patients.

The Correlation of Serum Chloride Level and Hospital Mortality in Multiple Trauma Patients

Introduction:

Electrolyte disorder is a prevalent complication in multiple trauma patients; nevertheless, the role of chloride has been rarely addressed in literature when evaluating serum electrolytes.

Objective:

The present study was conducted to determine the correlation between serum chloride changes and hospital mortality in multiple trauma patients.

Method:

The present cross-sectional study measured serum chloride levels in 100 multiple trauma patients upon their admission to the emergency department and 24 hours later. All these patients were followed up in terms of hospital mortality using their medical records. Exact logistic regression was used to measure the effects of independent variables on hospital mortality in the patients.

Results:

Hospital mortality was found to be 15 (15%), and the mean serum chloride level to be 106.37±4.53 mmol/l upon admission and 112.18±6.16 mmol/l 24 hours later. Although the univariate analysis suggested that serum chloride levels were independently associated with mortality 24 hours after admission (P=0.005), this correlation was insignificant in the multivariate analysis.

Conclusion:

The present study rejected the hypothesis suggesting the potential role of serum chloride levels in predicting hospital mortality in multiple trauma patients.

Association of Hyperchloremia With Unfavorable Clinical Outcomes in Adults With Diabetic Ketoacidosis

OBJECTIVE

Hyperchloremia is associated with worsened outcomes in various clinical situations; however, data are limited in patients with diabetic ketoacidosis (DKA). The purpose of this study was to determine the effect of hyperchloremia on time to DKA resolution.

METHODS

We conducted a retrospective cohort study of adult patients admitted with incident DKA from January 2013 through October 2017 and stratified by the development of hyperchloremia versus maintaining normochloremia. The primary outcome was time to final DKA resolution. Secondary outcomes included time to initial DKA resolution, incidence of acute kidney injury (AKI) on admission, in-hospital development of AKI, and hospital length of stay (LOS).

RESULTS

Of the 102 patients included, 52 developed hyperchloremia. Patients with hyperchloremia had longer times to final DKA resolution compared to those with normochloremia (median 22.3 [interquartile range, IQR, 15.2-36.9] vs 14.2 [IQR 8.8-21.1] hours; P = .001). Time to initial DKA resolution was also longer in patients who developed hyperchloremia compared to those who did not (median 16.3 vs 10.9 hours; P = .024). More patients with hyperchloremia developed in-hospital AKI (26.9% vs 8.0%; P = .01). Median hospital LOS was significantly longer in the hyperchloremia cohort (P < .001). On Cox regression analysis, time to DKA resolution was significantly longer with each 1 mmol/L increase in serum chloride (HR 0.951; P < .001).

CONCLUSION

The presence of hyperchloremia in patients with DKA was associated with increased time to DKA resolution, risk of in-hospital AKI, and hospital LOS. Further evaluation of the avoidance or treatment of hyperchloremia in DKA is needed.

Hyperchloremia and postoperative acute kidney injury: a retrospective analysis of data from the surgical intensive care unit

Background

Whether perioperative hyperchloremia can induce postoperative acute kidney injury (AKI) is controversial. We investigated the association between perioperative hyperchloremia and postoperative AKI in patients admitted to the intensive care unit (ICU) after surgery.

Methods

We performed a retrospective observational study of patients admitted to the surgical ICU at a single tertiary care hospital between January 2011 and June 2016. Our primary objective was to determine whether hyperchloremia or an increase in serum chloride levels was associated with postoperative AKI. Perioperative hyperchloremia was defined as serum chloride levels ≥ 110 mmol·L^− 1 during postoperative days (PODs) 0–3. The increase in serum chloride levels was defined as the difference between preoperative and maximum postoperative serum chloride levels during the first 3 days after surgery.

Results

Of the 7991 patients included in the final analysis, 1876 (23.5%) developed hyperchloremia during PODs 0–3, and 1187 (14.9%) developed postoperative AKI. Exposure to hyperchloremia during the first 3 days after surgery was not associated with postoperative AKI (odds ratio, 1.09; 95% confidence interval, 0.80–1.49; P = 0.571). However, among patients with preoperative chronic kidney disease stage ≥ 3 (estimated glomerular filtration rate < 60 mL·min^− 1·1.73·m^− 2), the incidence of postoperative AKI was higher in patients with an increase > 6 mmol·L^− 1 in serum chloride levels than in patients with an increase ≤ 1 mmol·L^− 1 (odds ratio, 1.42; 95% confidence interval, 1.09–1.84; P = 0.009). In addition, the incidence of postoperative AKI stage ≥ 2 was not associated with exposure to hyperchloremia or with the increase in serum chloride levels during PODs 0–3, regardless of preoperative kidney function.

Conclusions

Exposure to perioperative hyperchloremia is not associated with postoperative AKI in surgical ICU patients. However, in patients with moderate-to-severe chronic kidney disease (stage ≥ 3), a substantial perioperative increase in serum chloride levels may reflect a higher risk of AKI.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2216-5) contains supplementary material, which is available to authorized users.

Hyperchloremia Is Associated With Poorer Outcome in Critically Ill Stroke Patients

Background and Purpose: This study aims to explore the cause and predictive value of hyperchloremia in critically ill stroke patients.

Materials and Methods: We conducted a retrospective study of a prospectively collected database of adult patients with first-ever acute ischemic stroke (AIS) or intracerebral hemorrhage (ICH) admitted to the neurointensive care unit (NICU) of a university-affiliated hospital, between January 2013 and December 2016. Patients were excluded if admitted beyond 72 h from onset, if they required neurocritical care for less than 72 h, and were treated with hypertonic saline within 72 h or had creatinine clearance less than 15 mL/min.

Results: Of 405 eligible patients, the prevalence of hyperchloremia ([Cl⁻] ≥ 110 mmol/L) was 8.6% at NICU admission ([Cl⁻]₀) and 17.0% within 72 h ([Cl⁻]_max). Thirty-eight (9.4%) patients had new-onset hyperchloremia and 110 (27.1%) had moderate increase in chloride (Δ[Cl⁻] ≥ 5 mmol/L; Δ[Cl⁻] = [Cl⁻]_max − [Cl⁻]₀) in the first 72 h after admission, which were found to be determined by the sequential organ failure assessment score in multivariate logistic regression analysis. Neither total fluid input nor cumulative fluid balance had significant association with such chloride disturbance. New-onset hyperchloremia and every 5 mmol/L increment in Δ[Cl⁻] were both associated with increased odds of 30-day mortality and 6-month poor outcome, although no independent significance was found in multivariate models.

Conclusion: Hyperchloremia tends to occur in patients more severely affected by AIS and ICH. Although no independent association was found, new-onset hyperchloremia and every 5 mmol/L increment in Δ[Cl⁻] were related to poorer outcome in critically ill AIS and ICH patients.

Subject terms: clinical studies, intracranial hemorrhage, ischemic stroke, mortality/survival, quality and outcomes.

Acute kidney injury in trauma patients

PURPOSE OF REVIEW

To review epidemiology and pathophysiology of acute kidney injury (AKI) in trauma patients and propose strategies that aim at preventing AKI after trauma.

RECENT FINDINGS

AKI in trauma patients has been reported to be as frequent as 50% with an association to a prolonged length of stay and a raise in mortality. Among the specific risk factors encountered in trauma patients, hemorrhagic shock, rhabdomyolysis severity, age, and comorbidities are independently associated with AKI occurrence. Resuscitation with balanced solutes seems to have beneficial effects on renal outcome compared with NaCl 0.9%, particularly in the context of rhabdomyolysis. However, randomized clinical studies are needed to confirm this signal. Abdominal compartment syndrome (ACS) is rare but has to be diagnosed to initiate a dedicated therapy.

SUMMARY

The high incidence of AKI in trauma patients should lead to early identification of those at risk of AKI to establish a resuscitation strategy that aims at preventing AKI.

Chloride in intensive care units: a key electrolyte

Over the past few years, chloride has joined the league of essential electrolytes for critically ill patients. Dyschloremia can occur secondary to various etiologic factors before and during patient admission in the intensive care unit. Some cases are disease-related; others, treatment-related. Chloride abnormalities were shown in animal models to have adverse effects on arterial blood pressure, renal blood flow, and inflammatory markers, which have led to several clinical investigations. Hyperchloremia was studied in several settings and correlated to different outcomes, including death and acute kidney injury. Baseline hypochloremia, to a much lesser extent, has been studied and associated with similar outcomes. The chloride content of resuscitation fluids was also a subject of clinical research. In this review, we describe the effect of dyschloremia on outcomes in critically ill patients. We review the major studies assessing the chloride content of resuscitation fluids in the critically ill patient.

Choice of Fluids for Resuscitation of the Critically Ill: What Nurses Need to Know

Fluid administration is one of the most universal interventions in the intensive care unit; however, there remains a lack of optimal fluid choice in clinical practice. With increasing evidence suggesting that the choice and dose of fluid may influence patient outcomes, it is important to have an understanding of the differences between the various fluid products and these potential effects in order for nurses to navigate the critically ill patient. This article reviews properties, adverse effects, and monitoring of commonly used colloid and crystalloid fluids, providing information that may aid in fluid selection in the intensive care unit.

Clinical practice guideline adherence during Operation Inherent Resolve

BACKGROUND

The Joint Trauma System (JTS) clinical practice guidelines (CPGs) contributed to the decrease in battlefield mortality over the past 15 years. However, it is unknown to what degree the guidelines are being followed in current military operations.

METHODS

A retrospective review was performed of all patients treated at three separate US Army Role II facilities during the first 10 months of Operation Inherent Resolve in Iraq. Charts were reviewed for patient demographics, clinical care, and outcomes. Charts were also reviewed for compliance with JTS CPGs and Tactical Combat Casualty Care recommendations.

RESULTS

A total of 114 trauma patients were treated during the time period. The mean age was 26.9 ± 10.1 years, 90% were males, and 96% were host nation patients. The most common mechanisms of injury were blast (49%) and gunshot (42%). Records were compliant with documenting a complete set of vitals in 58% and a pain score in 50% of patients. Recommendations for treatment of hypothermia were followed for 97% of patients. Tranexamic acid was given outside guidelines for 6% of patients, and for 40%, it was not determined if the guidelines were followed. Recommendations for initial resuscitative fluid were followed for 41% of patients. Recommendations for antibiotic prophylaxis were followed for 40% of intra-abdominal and 73% of soft tissue injuries. Recommendations for tetanus prophylaxis were followed for 90% of patients. Deep vein thrombosis prophylaxis was given to 32% of patients and contraindicated in 27%. The recommended transfusion ratio was followed for 56% of massive transfusion patients. Recommendations for calcium administration were followed for 40% of patients. When composite scores were created for individual surgeons, there was significant variability between surgeons with regard to adherence to guidelines.

CONCLUSIONS

There is significant deviation in the adherence to the CPGs.

LEVEL OF EVIDENCE

Epidemiologic study, level IV.

Electrolyte Disturbances Are Associated with Non-Survival in Dogs-A Multivariable Analysis

Electrolyte disorders have been individually associated with mortality in small populations of dogs and cats with specific conditions, but the associations and interactions between electrolyte disturbances and outcome have not been evaluated in a large, heterogeneous population. It was hypothesized that abnormalities of sodium, chloride, potassium, and calcium concentrations would be independently and proportionately associated with death from natural causes and with all-cause mortality in dogs. An electronic database containing 33,117 electrolyte profiles was constructed to retrospectively assess the association between disorders of sodium, potassium, corrected chloride, and ionized calcium concentrations with non-survival and with death excluding euthanasia by multivariable modeling. A second database containing 11,249 records was used to validate the models constructed from the first database. All four electrolytes assessed had non-linear U-shaped associations with case fatality rates, wherein concentrations clustered around the reference interval had the lowest case fatality rates, while progressively abnormal concentrations were associated with proportionately increased risk of non-survival (AUROC 0.624) or death (AUROC 0.678). Multivariable modeling suggested that these electrolyte disturbances were associated with non-survival and with death from natural causes independent of each other. This study suggests that measurement of electrolyte concentrations is an important component of the assessment of dogs in emergency rooms or intensive care units. Future studies should focus on confirming these associations in a prospective manner accounting for disease severity.