The impact of obesity on sepsis mortality: a retrospective review

A tagging polymorphism in fat mass and obesity-associated (FTO) gene is associated with sepsis status in children

INTRODUCTION

Sepsis is one of the most common causes of death in patients admitted to intensive care units (ICUs). The development of sepsis is significantly influenced by genetic predisposition. In this study, we highlight a potential association between a variant of the fat mass and obesity-associated (FTO) gene and risk of sepsis in children and adolescents.

METHODS

We investigated a first-intron tagging FTO polymorphism (rs17817449) by comparing a severe condition (SC) group, comprising 598 paediatric patients (ages 0-19 years) admitted to an ICU with fever, systemic inflammatory response syndrome (SIRS), sepsis, severe sepsis, septic shock, or multiple organ dysfunction syndrome (MODS), with a control group consisting of 616 healthy young adults.

RESULTS

We observed a lower prevalence (p < 0.01; OR = 0.59, 95% CI = 0.39-0.87) of the FTO TT genotype in febrile and SIRS patients compared to patients with severe illness. There was a borderline trend towards a lower prevalence of the FTO TT genotype in the control group compared to the SC group (p < 0.09, OR = 0.81, 95% CI = 0.62-1.06).

CONCLUSIONS

Our findings suggest that rs17817449, a common FTO polymorphism, may be a predictor of sepsis in paediatric patients, and that higher body weight is protective against this clinical complication.

The obesity paradox in younger adult patients with sepsis: analysis of the MIMIC-IV database

BACKGROUND

The obesity paradox suggests that individuals with obesity may have a survival advantage against specific critical illnesses, including sepsis. However, whether this paradox occurs at younger ages remains unclear. Therefore, we aimed to investigate whether obesity could improve survival in younger adult patients with sepsis.

METHODS

We used clinical data sourced from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Patients with Sequential Organ Failure Assessment score ≥2 and suspected infection at the time of ICU admission were identified as having sepsis, following the Sepsis-3 definition. Individuals were classified into the obesity (BMI ≥30 kg/m²) and non-obesity (BMI <30 kg/m²) groups. Patients aged <50 and ≥50 years were categorized as younger adult patients and older patients, respectively.

RESULTS

Of 73,181 patients in the MIMIC-IV ICU database, 18,120 satisfied the inclusion criteria: 2642 aged <50 years and 15,478 aged ≥50 years. The Kaplan-Meier curve showed that obesity was not associated with an improved mortality rate among younger adult patients with sepsis (log-rank test: P = 0.197), while obesity exhibited a survival benefit in older patients with sepsis (log-rank test: P < 0.001). After propensity score matching, in-hospital mortality did not differ significantly between the obesity and non-obesity groups (13.3% vs. 12.2%; P = 0.457) in the younger adult patients with sepsis. Multivariate logistic regression analysis revealed that BMI was not an independent risk factor for in-hospital mortality in younger adult patients with sepsis (underweight: adjusted odds ratio [aOR] 1.72, P = 0.076; overweight: aOR 0.88, P = 0.437; obesity: aOR 0.93, P = 0.677; and severe obesity: aOR 1.22, P = 0.580, with normal weight as the reference).

CONCLUSION

Contrary to findings regarding older patients with sepsis, our findings suggest that the obesity paradox does not apply to younger adult patients with sepsis.

Metabolic syndrome induces benefits in mice experiencing severe sepsis, comparable to the effects of low-dose aspirin pretreatment in septic mice lacking metabolic syndrome

BACKGROUND

Sepsis is a complex condition characterized by systemic host inflammation caused by an infection. Experimental and observational studies indicate that obesity, one of the components of metabolic syndrome (MetS), or aspirin (ASA) treatment could be associated with sepsis survival. However, the effects of ASA on septic mice with MetS-induced conditions have not been explored.

METHODS

Swiss mice were administered monosodium glutamate (MSG) (4 mg/kg) during their first 5 days of life for MetS induction, while the control mice received an equimolar saline solution. MetS was validated in male mice on their 60th day of life. ASA treatment was administered for 15 days prior to sepsis (40 mg/kg). On the 75th day, sepsis was induced in MetS and control mice through cecal ligation and puncture (CLP). The effects of ASA on septic mice with MSG-induced MetS were assessed by determining survival rates, quantification of nitric oxide (NO), and cytokine levels in the plasma, while correlating these data with hematological, blood glucose and cardiovascular parameters.

RESULTS

MetS was validated by Lee-Index (3 body weight/naso-anal length×1000), hypertension, and hyperglycemia in animals receiving MSG as neonates. In control animals, severe sepsis promoted hypoglycemia, which was associated with mortality, as well as increased plasma NO levels, hypotension, hematological alterations, and elevation of proinflammatory cytokines. In contrast, MetS and pre-treatment with ASA were able to prevent sepsis-related alterations.

CONCLUSIONS

MetS and ASA pre-treatment provided protection against severe sepsis. However, ASA was ineffective in mice with MetS undergoing severe sepsis.

The effect of omentoplasty in various surgical operations: systematic review and meta-analysis

BACKGROUND

Omentoplasty is commonly used in various surgeries. However, its effectiveness is unsure due to lack of convincing data and research. To clarify the impact of omentoplasty on postoperative complications of various procedures, this systematic review and meta-analysis was performed.

METHODS

A systematic review of published literatures from four databases: PubMed, Web of Science, Cochrane Library, and Embase before 14 July 2022. The authors primarily included publications on five major surgical operations performed in conjunction with omentoplasty: thoracic surgery, esophageal surgery, gastrointestinal surgery, pelvi-perineal surgery, and liver surgery. The protocol was registered in PROSPERO.

RESULTS

This review included 25 273 patients from 91 studies ( n =9670 underwent omentoplasty). Omentoplasty was associated with a lower risk of overall complications particularly in gastrointestinal [relative risk (RR) 0.53; 95% CI: 0.39-0.72] and liver surgery (RR 0.54; 95% CI: 0.39-0.74). Omentoplasty reduced the risk of postoperative infection in thoracic (RR 0.38; 95% CI: 0.18-0.78) and liver surgery (RR 0.39; 95% CI: 0.29-0.52). In patients undergoing esophageal (RR 0.89; 95% CI: 0.80-0.99) and gastrointestinal (RR 0.28; 95% CI: 0.23-0.34) surgery with a BMI greater than 25, omentoplasty is significantly associated with a reduced risk of overall complications compared to patients with normal BMI. No significant differences were found in pelvi-perineal surgery, except infection in patients whose BMI ranged from 25 kg/m 2 to 29.9 kg/m 2 (RR 1.25; 95% CI: 1.04-1.50) and anastomotic leakage in patients aged over 60 (RR 0.59; 95% CI: 0.39-0.91).

CONCLUSION

Omentoplasty can effectively prevent postoperative infection. It is associated with a lower incidence of multiple postoperative complications in gastrointestinal and liver surgery.

Role of obesity in lower mortality risk in sepsis: a meta-analysis of observational studies

This meta-analysis aims to explore the correlation between obesity and mortality in patients with sepsis. Data were gathered from various sources, including PubMed, the Cochrane Library, and Embase (no language restrictions). Clinical studies, both retrospective and prospective ones, were selected to analyze mortality due to sepsis in patients with or without obesity. The Newcastle-Ottawa Scale was used to assess the quality of the studies included. In data synthesis, odds ratio (OR) and 95% confidence interval (CI) were meta-analyzed using the DerSimonian-Laird random-effects model, followed by sensitivity and heterogeneity analyses. Two cohort studies were included to investigate survival in inpatients with obesity and sepsis, with pooled analysis indicating a lowered mortality rate (OR=0.88; 95% CI: 0.81-0.95; I2=0.00%; P=0.000). This meta-analysis lends support to the obesity paradox, suggesting a reduced mortality from sepsis in obese patients. However, further prospective trials and research on mechanisms are needed to test this hypothesis.

Obesity and septic patient outcomes: Shaping the puzzle through age and sex perspectives

BACKGROUND & AIMS

While obesity has been reported as a protective factor in septic patients, little is known about the potential modifying effects of age and sex. The objective of this study is to investigate age and sex-specific associations between obesity and the prognosis of septic patients.

METHODS

A retrospective analysis was conducted on a cohort of 15,464 septic patients, categorized by body mass index (BMI) into four groups: underweight (<18.5 kg/m2, n = 483), normal (18.5-24.9 kg/m2, n = 4344), overweight (25-29.9 kg/m2, n = 4949) and obese (≥30 kg/m2, n = 5688). Multivariable logistic regression and inverse probability weighting were employed to robustly confirm the protective effect of a higher BMI on 28-day mortality, with normal weight serving as the reference category. Subgroup analyses based on age (young: 18-39, middle-aged: 40-64 and elderly: ≥65) and sex were performed.

RESULTS

The findings demonstrate that high BMI independently confers a protective effect against 28-day mortality in septic patients. However, the relationship between BMI and 28-day mortality exhibits a non-linear trend, with a BMI of 34.5 kg/m2 displaying the lowest odds ratio. Notably, the survival benefits associated with a high BMI were not observed in the young group. Moreover, being underweight emerges as an independent risk factor for middle-aged and elderly female patients, while in males it is only a risk factor in the elderly group. Interestingly, being overweight and obese were identified as independent protective factors in middle-aged and elderly male patients, but not in females.

CONCLUSIONS

The effect of BMI on mortality in septic patients varies according to age and sex. Elderly individuals with sepsis may derive more prognostic benefits from obesity.

Maternal consumption of a high-fat diet modulates the inflammatory response in their offspring, mediated by the M1 muscarinic receptor

Introduction

High-fat diet (HFD) consumption is associated with various metabolic disorders and diseases. Both pre-pregnancy and maternal obesity can have long-term consequences on offspring health. Furthermore, consuming an HFD in adulthood significantly increases the risk of obesity and metabolic disorders. However, an intriguing phenomenon known as the obesity paradox suggests that obesity may confer a protective effect on mortality outcomes in sepsis. In sepsis, activation of the cholinergic anti-inflammatory pathway (CAP) can help mitigate systemic inflammation. We employed a metabolic programming model to explore the relationship between maternal HFD consumption and offspring response to sepsis.

Methods

We fed female mice either a standard diet (SC) or an HFD during the pre-pregnancy, pregnancy, and lactation periods. Subsequently, we evaluated 28-day-old male offspring.

Results

Notably, we discovered that offspring from HFD-fed dams (HFD-O) exhibited a higher survival rate compared with offspring from SC-fed dams (SC-O). Importantly, inhibition of the m1 muscarinic acetylcholine receptor (m1mAChR), involved in the CAP, in the hypothalamus abolished this protection. The expression of m1mAChR in the hypothalamus was higher in HFD-O at different ages, peaking on day 28. Treatment with an m1mAChR agonist could modulate the inflammatory response in peripheral tissues. Specifically, CAP activation was greater in the liver of HFD-O following agonist treatment. Interestingly, lipopolysaccharide (LPS) challenge failed to induce a more inflammatory state in HFD-O, in contrast to SC-O, and agonist treatment had no additional effect. Analysis of spleen immune cells revealed a distinct phenotype in HFD-O, characterized by elevated levels of CD4+ lymphocytes rather than CD8+ lymphocytes. Moreover, basal Il17 messenger RNA (mRNA) levels were lower while Il22 mRNA levels were higher in HFD-O, and we observed the same pattern after LPS challenge.

Discussion

Further examination of myeloid cells isolated from bone marrow and allowed to differentiate showed that HFD-O macrophages displayed an anti-inflammatory phenotype. Additionally, treatment with the m1mAChR agonist contributed to reducing inflammatory marker levels in both groups. In summary, our findings demonstrate that HFD-O are protected against LPS-induced sepsis, and this protection is mediated by the central m1mAChR. Moreover, the inflammatory response in the liver, spleen, and bone marrow-differentiated macrophages is diminished. However, more extensive analysis is necessary to elucidate the specific mechanisms by which m1mAChR modulates the immune response during sepsis.

Loss of body weight and lean mass in long-stay, hospitalized canine patients

A high prevalence of malnutrition occurs in human hospitals and has been associated with detrimental consequences. By comparison, much less is known in hospitalized veterinary patients. The aims of this study were to evaluate the prevalence of malnutrition and body composition changes in long-stay hospitalised patients using an isotopic dilution technique. An additional objective was to compare the changes in composition with commonly used methods measuring body fat and lean mass. The dogs consumed on average 77.5% of their estimated resting energy requirements during their stay. The majority (78.3%) of dogs lost body weight, of which a greater proportion was lean mass (61.8%) than fat mass (FM) (38.2%). There was a moderate correlation between body condition score and percentage FM measured at admission (Kendall's τ = 0.51; p = 0.002), and at discharge (Kendall's τ = 0.55; p = 0.001). However, there was no correlation between muscle condition score and fat-free mass at either admission or discharge (p > 0.1). Duration of stay was positively associated with loss of body weight (p < 0.001), but was not associated with changes in either lean or FM expressed as a percentage of body weight or in absolute terms (p > 0.1), which was presumed to be explained by small sample size and variation. Food intake was not found to a significant factor for lean or FM loss (p > 0.1). These findings indicate that weight loss is common in hospitalized canine patients, which is not explained by simple under-eating. Other factors such as inflammation and inactivity should be evaluated in future studies to determine their role in influencing muscle and FM changes in hospitalized canine patients.

Association of obesity and mortality in sepsis patients: A meta-analysis from observational evidence

The project aims to investigate the correlation between obesity, overweight, or low body weight and the risk of mortality in sepsis patients. We performed a rigorous and thorough search of major electronic databases, including PubMed, Web of Science, EMBASE, and Cochrane Library, from the inception of these databases up to March 28, 2023. The data were analyzed with Stata software (version 16.0). Twelve studies incorporating 521,207 individuals were enrolled. The results demonstrated that obesity (OR = 0.82; 95% CI: 0.69-0.97; P < 0.001) or overweight (OR = 0.83; 95% CI: 0.73-0.94; P < 0.001) decreased the risk of mortality in sepsis patients. Instead, the reverse phenomena existed in patients with a low weight (OR = 1.43; 95%CI: 1.16-1.76; P = 0.038). There is an "obesity paradox" phenomenon in the mortality of obese and overweight patients with sepsis, but low body weight is an independent risk factor for the mortality of sepsis patients. This study demonstrated that the mortality in sepsis patients and obesity or overweight were negatively correlated, but displayed a significant positive relation to low weight.

Association of body mass index with mortality of sepsis or septic shock: an updated meta-analysis

BACKGROUND

The effects of body mass index (BMI) on mortality of sepsis remain unknown, since previous meta-analyses have reported conflicting results. Several observational studies published recently have provided new evidence. Thus, we performed this updated meta-analysis.

METHODS

PubMed, Embase, Web of Science, and Cochran Library were searched for articles published before February 10, 2023. Observational studies that assessed the association of BMIs with mortality of sepsis patients aged > 18 years were selected. We excluded studies of which data were unavailable for quantitative synthesis. Odds ratios (OR) with 95% confidence interval (CI) were the effect measure, which were combined using fixed-effect or random-effect models. The Newcastle-Ottawa Scale was applied for quality assessment. Subgroups analyses were conducted according to potential confounders.

RESULTS

Fifteen studies (105,159 patients) were included in the overall analysis, which indicated that overweight and obese BMIs were associated with lower mortality (OR: 0.79, 95% CI 0.70-0.88 and OR: 0.74, 95% CI 0.67-0.82, respectively). The association was not significant in patients aged ≤ 50 years (OR: 0.89, 95% CI 0.68-1.14 and OR: 0.77, 95% CI 0.50-1.18, respectively). In addition, the relationship between morbidly obesity and mortality was not significant (OR: 0.91, 95% CI 0.62-1.32).

CONCLUSIONS

Overweight and obese BMIs (25.0-39.9 kg/m²) are associated with reduced mortality of patients with sepsis or septic shock, although such survival advantage was not found in all crowds. Trial registration The protocol of this study was registered in PROSPERO (registration number CRD42023399559).

Linking Sepsis with chronic arterial hypertension, diabetes mellitus, and socioeconomic factors in the United States: A scoping review

RATIONALE

Sepsis is a syndrome of life-threatening organ dysfunction caused by a dysregulated host immune response to infection. Social risk factors including location and poverty are associated with sepsis-related disparities. Understanding the social and biological phenotypes linked with the incidence of sepsis is warranted to identify the most at-risk populations. We aim to examine how factors in disadvantage influence health disparities related to sepsis.

METHODS

A scoping review was performed for English-language articles published in the United States from 1990 to 2022 on PubMed, Web of Science, and Scopus. Of the 2064 articles found, 139 met eligibility criteria and were included for review.

RESULTS

There is consistency across the literature of disproportionately higher rates of sepsis incidence, mortality, readmissions, and associated complications, in neighborhoods with socioeconomic disadvantage and significant poverty. Chronic arterial hypertension and diabetes mellitus also occur more frequently in the same geographic distribution as sepsis, suggesting a potential shared pathophysiology.

CONCLUSIONS

The distribution of chronic arterial hypertension, diabetes mellitus, social risk factors associated with socioeconomic disadvantage, and sepsis incidence, are clustered in specific geographical areas and linked by endothelial dysfunction. Such population factors can be utilized to create equitable interventions aimed at mitigating sepsis incidence and sepsis-related disparities.

SEX-DEPENDENT EFFECTS OF ADIPOCYTE STAT3 INHIBITION ON THE INFLAMMATORY RESPONSE DURING SEVERE SEPSIS

ABSTRACT

Introduction: Sepsis is a dysregulated host response to infection that can lead to life-threatening organ dysfunction. Clinical and animal studies consistently demonstrate that female subjects are less susceptible to the adverse effects of sepsis, demonstrating the importance of understanding how sex influences sepsis outcomes. The signal transducer and activator of transcription 3 (STAT3) pathway are a major signaling pathway that facilitates inflammation during sepsis. STAT3 is abundantly expressed in white adipose tissue; however, little is known about the contribution of white adipose tissue STAT3 activation during sepsis. We hypothesize that adipocyte STAT3 inhibition during severe sepsis will exaggerate the inflammatory response and impact organ injury, in a sex-dependent manner. Methods: We generated STAT3 flox/flox (wild-type [WT]) and adipocyte STAT3 knock out (A-STAT3 KO) mice using Cre-lox technology. Studies were done in 12- to 16-week-old male and female mice. Polymicrobial sepsis was induced by cecal ligation and puncture (CLP). Control nonseptic mice did not undergo CLP (0 h CLP). Tissues were harvested 18 h after CLP. Body composition was determined by echo magnetic resonance imaging. Energy metabolism was determined by indirect calorimetry. White adipose tissue morphology was determined by hematoxylin and eosin staining, while STAT3 activation in the white adipose tissue was determined by western blot analysis and immunohistochemistry staining of STAT3 activation/phosphorylation at tyrosine 705. Plasma cytokines (TNF-α, IL-6, and leptin) were determined by luminex assay. Neutrophil infiltration of the lung and liver was assessed by myeloperoxidase activity assay. Histological signs of organ injury on lung and liver tissue were assessed by hematoxylin and eosin staining. Liver injury was further assessed by measuring plasma alanine and aspartate aminotransferase. In a separate cohort of mice, sepsis was induced by CLP and mice were monitored every 6-12 h over a 7-day period to assess survival rate. Results: We demonstrate that neither body composition nor energy metabolism is altered with adipocyte STAT3 inhibition in male or female mice, under nonseptic conditions. Sepsis was associated with reduced adipocyte size in female WT and A-STAT3 KO mice, suggesting that this event is STAT3 independent. Sepsis did not alter adipocyte size in male WT and A-STAT3 KO mice, suggesting that this event is also sex dependent. Although STAT3 phosphorylation at tyrosine 705 expression is negligible in male and female A-STAT3 KO mice, septic female WT and A-STAT3 KO mice have higher white adipose tissue STAT3 activation than male WT and A-STAT3 KO mice. Adipocyte STAT3 inhibition did not alter the proinflammatory cytokine response during sepsis in male or female mice, as measured by plasma TNF-α, IL-6, and leptin levels. Adipocyte STAT3 inhibition reduced lung neutrophil infiltration and histological signs of lung injury during sepsis in male mice. On the contrary, adipocyte STAT3 inhibition had no effect on lung neutrophil infiltration or lung injury in female mice. We further demonstrate that neither liver neutrophil infiltration nor histological signs of liver injury are altered by adipocyte STAT3 inhibition during sepsis, in male or female mice. Lastly, adipocyte STAT3 inhibition did not affect survival rate of male or female mice during sepsis. Conclusions: Our study demonstrates that sex influences white adipose tissue STAT3 activation and morphology during sepsis, which is not dependent on the presence of functional STAT3 in mature adipocytes. Furthermore, genetic inhibition of adipocyte STAT3 activation in male, but not female mice, results in reduced lung neutrophil infiltration and lung injury during sepsis. The results from our study demonstrate the importance of considering biological sex and the white adipose tissue as potential sources and targets of inflammation during sepsis.

Association between obesity and 1-year mortality in septic patients: a retrospective cohort study

OBJECTIVE

Sepsis is a major contributor of intensive care units (ICUs) patient mortality. Prior investigations claimed that obesity enhances overall survival (OS) of septic patients. However, the reported results were inconsistent. This study examined the association between obesity and the 1-year mortality of septic patients.

DESIGN

A retrospective cohort study.

SETTING

The Medical Information Mart for Intensive Care III database.

PARTICIPANTS

3145 septic patients were separated into three distinct cohorts, based on their WHO body mass index (BMI) status.

OUTCOMES

Our primary endpoint was the 1-year mortality from the date of ICU hospitalization.

RESULT

1334 (42.4%) died within 1 year. The 1-year mortality rate was low in obese patients (38.8%), compared with normal (46.9%) and overweight (42.1%) patients. Crude assessment revealed that obese patients experienced reduced 1-year mortality, relative to normal weight patients (HR 0.79, 95% CI 0.69 to 0.9, p<0.001). However, once adjusted for baseline variables and comorbidities, no correlation was found between obesity and the 1-year mortality (HR 0.93, 95% CI 0.81 to 1.06, p=0.28) of septic patients. There was an association among diabetic (HR 0.72, 95% CI 0.56 to 0.93, p=0.012) and hypertensive (HR 0.73, 95% CI 0.58 to 0.92, p=0.008) patients, and among males (HR 0.71, 95% CI 0.59 to 0.86, p<0.001), with obese individuals experiencing the lowest mortality rate. Given these evidences, the interactions between BMI and mortality in diabetic (p=0.031) and hypertensive (p=0.035) patients were significant.

CONCLUSION

In our study, obese diabetic and hypertensive patients associated to less sepsis-related mortality risk, compared with normal weight patients. Further researches were need to validated.

Divergent Sepsis Pathophysiology in Older Adults

Significance: Both incidence and mortality rates of sepsis significantly increase with advanced age, and the majority of sepsis patients are late middle-aged or older. With the proportion of older adults rapidly increasing in developed countries, age-dependent sepsis vulnerability is an urgent medical issue. Due to an increasing life expectancy, postsepsis complications and health care costs are expected to increase as well. Recent Advances: Older patients suffer from higher sepsis incidence and mortality rates, likely resulting from frequent comorbidities, increased coagulation, dysgylcemia, and altered immune responses. Critical Issues: Despite a large number of ongoing clinical and basic research studies, there is currently no effective therapeutic strategy targeting older patients with severe sepsis. The disparity between clinical and basic studies is a problem, and this is largely due to the use of animal models lacking clinical relevance. Although the majority of sepsis cases occur in older adults, most laboratory animals used for sepsis research are very young. Further, despite the wide use of combination fluid and antibiotic treatment in intensive care unit (ICU) patients, most animal research does not include such treatment. Future Directions: Because sepsis is a systemic disease with multiple organ dysfunction, combined therapy approaches, not those targeting single pathways or single organs, are essential. As for preclinical research, it is critical to confirm new findings using aged animal models with clinically relevant ICU-like medical treatments. Antioxid. Redox Signal. 35, 1358-1375.

The Impact of Obesity on Critical Illnesses

ABSTRACT

In the last few decades, obesity became one of the world's greatest health challenges reaching a size of global epidemic in virtually all socioeconomic statuses and all age groups. Obesity is a risk factor for many health problems and as its prevalence gradually increases is becoming a significant economic and health burden. In this manuscript we describe how normal respiratory and cardiovascular physiology is altered by obesity. We review past and current literature to describe how obesity affects outcomes of patients facing critical illnesses and discuss some controversies related to this topic.

Adipocyte inflammation and pathogenesis of viral pneumonias: an overlooked contribution

Epidemiological evidence establishes obesity as an independent risk factor for increased susceptibility and severity to viral respiratory pneumonias associated with H1N1 influenza and SARS-CoV-2 pandemics. Given the global obesity prevalence, a better understanding of the mechanisms behind obese susceptibility to infection is imperative. Altered immune cell metabolism and function are often perceived as a key causative factor of dysregulated inflammation. However, the contribution of adipocytes, the dominantly altered cell type in obesity with broad inflammatory properties, to infectious disease pathogenesis remains largely ignored. Thus, skewing of adipocyte-intrinsic cellular metabolism may lead to the development of pathogenic inflammatory adipocytes, which shape the overall immune responses by contributing to either premature immunosenescence, delayed hyperinflammation, or cytokine storm in infections. In this review, we discuss the underappreciated contribution of adipocyte cellular metabolism and adipocyte-produced mediators on immune system modulation and how such interplay may modify disease susceptibility and pathogenesis of influenza and SARS-CoV-2 infections in obese individuals.

Association between body mass index and short-term mortality in patients with intra-abdominal infections: a retrospective, single-centre cohort study using the Medical Information Mart for Intensive Care database

OBJECTIVES

This study aimed to determine the relationship between the body mass index (BMI) and short-term mortality of patients with intra-abdominal infection (IAI) using the Medical Information Mart for Intensive Care (MIMIC-III) database.

DESIGN

Retrospective cohort study.

SETTING

Adult intensive care units (ICUs) at a tertiary hospital in the USA .

PARTICIPANTS

Adult IAI ICU patients from 2001 to 2012 in the MIMIC-III database.

INTERVENTIONS

In univariate analysis, we compared the differences in the characteristics of patients in each BMI group. Cox regression models were used to evaluate the relationships between BMI and short-term prognosis.

PRIMARY AND SECONDARY OUTCOME MEASURES

90-day survival.

RESULTS

In total, 1161 patients with IAI were included. There were 399 (34.4%) patients with a normal BMI (<25 kg/m²), 357 (30.8%) overweight patients (25-30 kg/m²) and 405 (34.9%) obese patients (>30 kg/m²) who tended to be younger (p<0.001) and had higher Sequential Organ Failure Assessment scores (p<0.05). The mortality of obese patients at 90 days was lower than that of patients with a normal BMI (20.74% vs 23.25%, p<0.05), but their length of stay in the ICU was higher (4.9 days vs 3.6 days, p<0.001); however, their rate of mechanical ventilation utilisation was higher (61.48% vs 56.86%, p<0.05). In the Cox regression model, we also confirmed that BMI was a protective factor in patients with IAIs, and the adjusted mortality rate of patients with a higher BMI was 0.97 times lower than that of patients with a lower BMI (p<0.001, HR=0.97, 95% CI 0.96 to 0.99).

CONCLUSIONS

IAI patients with an overweight or obese status might have lower 90-day mortality than patients with a normal BMI.

Association Between Body Mass Index and Outcomes in Venoarterial Extracorporeal Membrane Oxygenation

BACKGROUND

The association between obesity, or elevated body mass index (BMI), and outcomes in patients receiving venoarterial extracorporeal membrane oxygenation (VA-ECMO) has not been well established. Recent studies in patients receiving venovenous ECMO did not detect an association between obesity and increased mortality. The purpose of this retrospective observational study is to evaluate the association between BMI and survival in patients receiving VA-ECMO for cardiogenic shock.

METHODS

All patients >18 years of age supported on VA-ECMO for refractory cardiogenic shock in a single academic center between 2009 and 2019 were included. ECMO outcomes, including successful ECMO decannulation and 30-day survival, were analyzed after stratification according to BMI. Multivariable and univariate logistic regression were used to assess the association between BMI and VA-ECMO outcomes.

RESULTS

Of the total patients (n = 355) cannulated for VA-ECMO, 61.7% of the patients survived to ECMO recovery/decannulation, 45.5% of the patients survived to 30 days after ECMO decannulation, and 38.9% of the patients survived to hospital discharge with no statistically significant differences among the BMI groups. Multivariable logistic regression did not reveal any associations between obesity as defined by BMI and survival to ECMO decannulation (odds ratio [OR] 1.07 per 5 unit increase in BMI, 95% confidence interval [CI], 0.86-1.33; P = .57), 30-day survival (OR = 0.91, 95% CI, 0.73-1.14; P = .41) or survival to hospital discharge (OR = 0.95, 95% CI, 0.75-1.20; P = .66).

CONCLUSIONS

Despite potential challenges to cannulation and maintaining adequate flow during ECMO, this single centered, retrospective observational study did not detect association between BMI and survival to ECMO decannulation, 30-day survival, or survival to hospital discharge for patients requiring VA-ECMO for refractory cardiogenic shock. These data suggest that obesity alone should not exclude candidacy for VA-ECMO. The primary outcome in this retrospective study was survival of the ECMO therapy (survival to ECMO decannulation), defined as surviving >24 hours after decannulation without a withdrawal of care. Secondary outcomes included survival at 30 days and survival to hospital discharge.

Effect of obesity on mortality among hospitalized paediatric patients with severe sepsis

INTRODUCTION

Severe sepsis is one of the leading causes of mortality among children. Studies in adults have suggested a protective effect of obesity on mortality among patients hospitalized with sepsis. Paediatric studies evaluating similar relationship is lacking.

METHODS

We analysed non-overlapping years of the Kids Inpatient Database (KID) and National Inpatient Sample (NIS) database between 2003 and 2014 of all paediatric patients with severe sepsis (PSS) up to 20 years of age. PSS was defined using specific International Classification of Diseases (ICD) codes and modified Angus criteria. Using ICD-9 diagnosis codes, patients were divided into three mutually exclusive groups (obesity, morbid obesity and control groups), and these groups were compared for outcomes measures including in-hospital mortality and healthcare resource utilization using the length of stay and inflation-adjusted hospitalization charges.

RESULTS

We analysed 109 026 hospitalizations due to PSS. The prevalence rate of obesity was 1.5% (n = 1643), and morbid obesity was 1.05% (n = 1147). Multivariate regression models showed obesity was associated with 63% (OR 0.37, CI: 0.29-0.47, p < 0.001) and 54% reduction in mortality among PSS patients and patients with septic shock respectively. Contrastingly, morbid obesity was not associated with mortality among PSS patients and but was associated with 1.37 times (CI: 1.06-1.78, p = 0.01) increased risk of mortality among paediatric patients with septic shock.

CONCLUSIONS

Paediatric obesity is associated with reduced mortality among patients with PSS, with the exception of morbid obesity. Further prospective studies are needed to better understand the relationship between obesity and outcomes in PSS.

Associations between low body mass index and mortality in patients with sepsis: A retrospective analysis of a cohort study in Japan

Background

The distribution of body mass in populations of Western countries differs from that of populations of East Asian countries. In East Asian countries, fewer people have a high body mass index than those in Western countries. In Japan, the country with the highest number of older adults worldwide, many people have a low body mass index. Therefore, this study aimed to determine the association between a low body mass index and mortality in patients with sepsis in Japan.

Methods

We conducted this retrospective analysis of 548 patients with severe sepsis from a multicenter prospective observational study. Multivariate logistic regression analyses determined the association between body mass index and 28-day mortality adjusted for age, sex, pre-existing conditions, the occurrence of septic shock, Acute Physiology and Chronic Health Evaluation II scores, and Sequential Organ Failure Assessment scores. Furthermore, the association between a low body mass index and 28-day mortality was analyzed.

Results

The low body mass index group represented 18.8% of the study population (103/548); the normal body mass index group, 57.3% (314/548); and the high body mass index group, 23.9% (131/548), with the 28-day mortality rates being 21.4% (22/103), 11.2% (35/314), and 14.5% (19/131), respectively. In the low body mass index group, the crude and adjusted odds ratios (95% confidence intervals) for 28-day mortality relative to the non-low body mass index (normal and high body mass index groups combined) group were 2.0 (1.1–3.4) and 2.3 (1.2–4.2), respectively.

Conclusion

A low body mass index was found to be associated with a higher 28-day mortality than the non-low body mass index in patients with sepsis in Japan. Given that older adults often have a low body mass index, these patients should be monitored closely to reduce the occurrence of negative outcomes.

Impact of Body Mass Index on the Survival of Patients with Sepsis with Different Modified NUTRIC Scores

Nutritional status affects the survival of patients with sepsis. This retrospective study analyzed the impact of body mass index (BMI) and modified nutrition risk in critically ill (mNUTRIC) scores on survival of these patients. Data of 1291 patients with sepsis admitted to the intensive care unit (ICU) were extracted. The outcomes were mortality, duration of stay, ICU stay, and survival curve for 90-day mortality. Logistic regression analysis was performed to examine the risk factors for mortality. Cytokine and biomarker levels were analyzed in 165 patients. The 90-day survival of underweight patients with low mNUTRIC scores was significantly better than that of normal-weight patients with low mNUTRIC scores (70.8% vs. 58.3%, respectively; p = 0.048). Regression model analysis revealed that underweight patients with low mNUTRIC scores had a lower risk of mortality (odds ratio = 0.557; p = 0.082). Moreover, normal-weight patients with low mNUTRIC scores had the lowest human leukocyte antigen DR (HLA-DR) level on days 1 (underweight vs. normal weight vs. overweight: 94.3 vs. 82.1 vs. 94.3, respectively; p = 0.007) and 3 (91.8 vs. 91.0 vs. 93.2, respectively; p = 0.047). Thus, being underweight may not always be harmful if patients have optimal clinical nutritional status. Additionally, HLA-DR levels were the lowest in patients with low survival.

Impact of obesity on outcome of severe bacterial infections

Introduction

Obesity is a rapidly growing global health concern with considerable negative impact on life-time expectancy. It has yet not been clarified if and how obesity impacts outcomes of severe bacterial infections. The aim of this study was to determine how body mass index impacts outcome of severe bacterial infections in a well-defined population-based cohort.

Methods

This study is based on a cohort of 2196 patients included in a Swedish prospective, population-based, consecutive observational study of the incidence of community-onset severe sepsis and septic shock in adults. All patients with weight and height documented in the medical records on admission were included.

Results

The case fatality rate (CFR) was negatively correlating with increasing BMI. Outcomes included 28-day CFR (p-value = 0.002), hospital CFR (p-value = 0.039) and 1-year CFR (p-value<0.001). When BMI was applied as continuous variable in a multiple logistic regression together with other possible covariates, we still could discern that BMI was associated with decreasing 28-day CFR (OR = 0.93, 95% CI 0.88–0.98, p-value = 0.009) and 1-year CFR (OR = 0.94, 95% CI 0.91–0.97, p-value<0.001).

Conclusion

The hypothesis and paradox of obesity being associated with higher survival rates in severe bacterial infections was confirmed in this prospective, population-based observational study.

The Association Between Body Mass Index and the Risk of Hospitalization and Mortality due to Infection: A Prospective Cohort Study

Background

We aim to determine whether obesity increases the risk of various infections using a large prospective population-based cohort.

Methods

A total of 120 864 adults were recruited from the New Taipei City health screening program from 2005 to 2008. Statistics for hospitalization and mortality due to infection were obtained from the National Health Insurance Database and the National Death Registry in Taiwan.

Results

During a mean follow-up period of 7.61 years, there were 438, 7582, 5298, and 1480 first hospitalizations due to infection in the underweight, normal, overweight, and obese groups, respectively. Obesity significantly increases the risk of hospitalization for intra-abdominal infections (adjusted hazard ratio [aHR], 1.19; 95% CI, 1.00–1.40), including diverticulitis, liver abscess, acute cholecystitis and anal and rectal abscess, reproductive and urinary tract infection (aHR, 1.38; 95% CI, 1.26–1.50), skin and soft tissue infection (aHR, 2.46; 95% CI, 2.15–2.81), osteomyelitis (aHR, 1.70; 95% CI, 1.14–2.54), and necrotizing fasciitis (aHR, 3.54; 95% CI,1.87–6.67), and this relationship is dose-dependent. This study shows that there is a U-shaped association between body mass index (BMI) and hospitalization for lower respiratory tract infection, septicemia, and the summation of all infections and that underweight people are at the greatest risk, followed by obese people. There is a clear negative relationship between BMI and infection-related mortality.

Conclusions

The pattern that BMI affects the risk of hospitalization and mortality due to infection varies widely across infection sites. It is necessary to tailor preventive and therapeutic measures against different infections in hosts with different BMIs.

Does Obesity Protect Against Death in Sepsis? A Retrospective Cohort Study of 55,038 Adult Patients

OBJECTIVES

Observational studies suggest obesity is associated with sepsis survival, but these studies are small, fail to adjust for key confounders, measure body mass index at inconsistent time points, and/or use administrative data to define sepsis. To estimate the relationship between body mass index and sepsis mortality using detailed clinical data for case detection and risk adjustment.

DESIGN

Retrospective cohort analysis of a large clinical data repository.

SETTING

One-hundred thirty-nine hospitals in the United States.

PATIENTS

Adult inpatients with sepsis meeting Sepsis-3 criteria.

EXPOSURE

Body mass index in six categories: underweight (body mass index < 18.5 kg/m), normal weight (body mass index = 18.5-24.9 kg/m), overweight (body mass index = 25.0-29.9 kg/m), obese class I (body mass index = 30.0-34.9 kg/m), obese class II (body mass index = 35.0-39.9 kg/m), and obese class III (body mass index ≥ 40 kg/m).

MEASUREMENTS

Multivariate logistic regression with generalized estimating equations to estimate the effect of body mass index category on short-term mortality (in-hospital death or discharge to hospice) adjusting for patient, infection, and hospital-level factors. Sensitivity analyses were conducted in subgroups of age, gender, Elixhauser comorbidity index, Sequential Organ Failure Assessment quartiles, bacteremic sepsis, and ICU admission.

MAIN RESULTS

From 2009 to 2015, we identified 55,038 adults with sepsis and assessable body mass index measurements: 6% underweight, 33% normal weight, 28% overweight, and 33% obese. Crude mortality was inversely proportional to body mass index category: underweight (31%), normal weight (24%), overweight (19%), obese class I (16%), obese class II (16%), and obese class III (14%). Compared with normal weight, the adjusted odds ratio (95% CI) of mortality was 1.62 (1.50-1.74) for underweight, 0.73 (0.70-0.77) for overweight, 0.61 (0.57-0.66) for obese class I, 0.61 (0.55-0.67) for obese class II, and 0.65 (0.59-0.71) for obese class III. Results were consistent in sensitivity analyses.

CONCLUSIONS

In adults with clinically defined sepsis, we demonstrate lower short-term mortality in patients with higher body mass indices compared with those with normal body mass indices (both unadjusted and adjusted analyses) and higher short-term mortality in those with low body mass indices. Understanding how obesity improves survival in sepsis would inform prognostic and therapeutic strategies.

Sepsis Patients in Critical Care Units with Obesity: Is Obesity Protective?

Obesity is becoming a global health issue and its prevalence is increasing. It is associated with an increased incidence of illness and sepsis. While obesity is associated with increased morbidity and mortality, obesity has been found to be associated with improvement in mortality outcomes in sepsis when compared to leaner patients, a phenomenon described as an obesity paradox. However, the effect of obesity on mortality in adults requiring treatment for sepsis is unclear. Studies evaluating this effect are inconsistent and there is an increased morbidity still associated with obesity. As well, there are many limitations to these studies confounding interpretation. Future prospective studies minimizing bias and confounding factors are suggested to address this important clinical issue.

The Role of Adipose Tissue and Adipokines in Sepsis: Inflammatory and Metabolic Considerations, and the Obesity Paradox

PURPOSE

Sepsis has become a global health problem with rising incidence and high mortality, creating a substantial social and economic burden. Early diagnosis and treatment can improve outcome, but reliable sepsis biomarkers are lacking. This review summarizes current evidence of the pathophysiological mechanisms linking adipose tissue to sepsis and presents experimental and clinical data on adipokines and sepsis along with important insights into the obesity paradox in sepsis survival.

RECENT FINDINGS

Sepsis is characterized by significant alterations in circulating cytokines and adipokines, biologically active molecules produced by the adipose tissue, being implicated in metabolic and inflammatory processes. Although data are inconclusive regarding classic adipokines such as leptin and adiponectin, recent evidence have highlighted the striking elevation of resistin and visfatin in critical illness and sepsis as well as their association with sepsis severity and outcomes. Given that inflammatory and metabolic pathways are involved in sepsis, studying adipokines presents an attractive, innovative, and promising research field that may provide more powerful diagnostic and prognostic biomarkers as well as novel therapeutic targets, empowering the therapeutic armamentarium for sepsis management in order to improve survival.

Obesity and 1-Year Mortality in Adults After Sepsis: A Systematic Review

PURPOSE

In recent years, researchers have noted an "obesity paradox," where individuals with obesity survive sepsis at higher rates than their nonobese counterparts. This systematic review summarizes the literature on studies examining the association between obesity and 1-year mortality among patients admitted with sepsis, severe sepsis, or septic shock.

MATERIALS AND METHODS

Using a comprehensive search strategy, a systematic review was conducted to identify studies examining the association of obesity and sepsis mortality. PubMed, Cumulative Index of Nursing and Allied Health Literature, and Elton B. Stephens Company host databases were searched for the terms sepsis, obesity, mortality, and adult.

RESULTS

The initial search identified 189 studies, 9 of which met inclusion criteria. Of these, four provided evidence that obese or very obese patients with sepsis have lower mortality than nonobese patients. Methodologic differences in the remaining five studies, which reported conflicting results, limit generalizability.

CONCLUSION

This systematic review on the association of obesity and sepsis mortality found three studies that demonstrated lower sepsis mortality among obese patients in the first 30 days and one showing that this protective effect extends up to 1 year. Given the increased number of patients surviving sepsis, it is important to consider long-term mortality and further describe the variables associated with increased survival.

Refined carbohydrates, phenotypic plasticity and the obesity epidemic

The major change in the United States and European diets associated with the increased rates of obesity was an increased consumption of refined carbohydrates. A feature of refined carbohydrates is their predisposition to cause increased fluctuations in plasma insulin and glucose levels and postprandial reactive hypoglycaemia. As the central nervous system is dependent on a stable supply of glucose this threatens the central nervous system functioning and these fluctuations also have a negative impact on the cardiovascular system. Phenotypic plasticity enables organisms to use adaptive phenotypes already in existence such as the increased insulin resistance and increased adiposity associated with pregnancy or the insulin resistance associated with infection, trauma and burns or to evolve new phenotypes to adapt to variations in the environment. This paper explores the evidence that increased insulin resistance that is commonly associated with increased adiposity possibly because of shared locations on the genome is a phenotypic plastic adaptation to the increased consumption of refined carbohydrates and their predisposition to cause increased fluctuations in plasma insulin and plasma glucose and post-prandial reactive hypoglycaemia both of which have negative impacts on the metabolism. Obesity, that is a relatively stable state of increased adiposity and insulin resistance has adaptive and defensive features to these fluctuations in plasma insulin and glucose in that metabolic disorders associated with refined carbohydrate consumption are often mitigated and modified as exemplified by the obesity paradox.

Body Habitus and Risk of Mortality in Pediatric Sepsis and Septic Shock: A Retrospective Cohort Study

OBJECTIVE

To investigate the association between body habitus and mortality in critically ill children with sepsis or septic shock.

STUDY DESIGN

This was a retrospective cohort study of prospectively collected data of children admitted to US pediatric intensive care units (PICUs) with a primary or secondary diagnosis of sepsis or septic shock. We separated body habitus into underweight, normal weight, overweight, and obese. Outcomes were mortality (primary), treatment with invasive mechanical ventilation (secondary), and time to PICU discharge for survivors (secondary). Multivariable analyses using mixed-effects logistic regression and shared frailty models clustered by unit and adjusted for confounding variables were used to assess the association between body habitus and outcomes.

RESULTS

There were 7038 children with sepsis or septic shock. Mortality was 10.1% (n = 714) and 52.9% (n = 3720) required invasive mechanical ventilation. Body habitus was not associated with mortality after controlling for hospital level effects and confounding variables. Children who were overweight and obese had greater odds of invasive mechanical ventilation (overweight OR 1.23 [95% CI 1.05-1.45], P = .011 and obese OR 1.57 [95% CI 1.37-1.80], P < .001) compared with children of normal weight. In survivors treated with invasive mechanical ventilation, children who were obese had a longer time to PICU discharge than children of normal weight (obese hazard ratio for discharge 0.84 [95% CI, 0.77-0.92], P < .0001).

CONCLUSIONS

There was no association between body habitus and mortality in critically ill children with sepsis. Children who were overweight and obese were more likely to receive invasive mechanical ventilation and mechanically ventilated survivors who were obsese had a longer time to PICU discharge.

Characteristics, management, and in-hospital mortality among patients with severe sepsis in intensive care units in Japan: the FORECAST study

Background

Sepsis is a leading cause of death and long-term disability in developed countries. A comprehensive report on the incidence, clinical characteristics, and evolving management of sepsis is important. Thus, this study aimed to evaluate the characteristics, management, and outcomes of patients with severe sepsis in Japan.

Methods

This is a cohort study of the Focused Outcomes Research in Emergency Care in Acute Respiratory Distress Syndrome, Sepsis, and Trauma (FORECAST) study, which was a multicenter, prospective cohort study conducted at 59 intensive care units (ICUs) from January 2016 to March 2017. We included adult patients with severe sepsis based on the sepsis-2 criteria.

Results

In total, 1184 patients (median age 73 years, interquartile range (IQR) 64–81) with severe sepsis were admitted to the ICU during the study period. The most common comorbidity was diabetes mellitus (23%). Moreover, approximately 63% of patients had septic shock. The median Sepsis-related Organ Failure Assessment (SOFA) score was 9 (IQR 6–11). The most common site of infection was the lung (31%). Approximately 54% of the participants had positive blood cultures. The compliance rates for the entire 3-h bundle, measurement of central venous pressure, and assessment of central venous oxygen saturation were 64%, 26%, and 7%, respectively. A multilevel logistic regression model showed that closed ICUs and non-university hospitals were more compliant with the entire 3-h bundle. The in-hospital mortality rate of patients with severe sepsis was 23% (21–26%). Older age, multiple comorbidities, suspected site of infection, and increasing SOFA scores correlated with in-hospital mortality, based on the generalized estimating equation model. The length of hospital stay was 24 (12–46) days. Approximately 37% of the patients were discharged home after recovery.

Conclusion

Our prospective study showed that sepsis management in Japan was characterized by a high compliance rate for the 3-h bundle and low compliance rate for central venous catheter measurements. The in-hospital mortality rate in Japan was comparable to that of other developed countries. Only one third of the patients were discharged home, considering the aging population with multiple comorbidities in the ICUs in Japan.

Trial registration

UMIN-CTR, UMIN000019742. Registered on 16 November 2015.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2186-7) contains supplementary material, which is available to authorized users.

High Fat Diets Composed of Palm Stearin and Olive Oil Equally Exacerbate Liver Inflammatory Damage and Metabolic Stress in Mice

SCOPE

People with fatty liver could be subject to acute infections such as sepsis. The aim of the study is to evaluate the effect of high fat diets (HFD) of olive oil and palm stearin on liver inflammation induced by lipopolysaccharides (LPS).

METHODS AND RESULTS

C57BL/6J male mice were treated with high fat diets with different sources of oils: palm stearin and olive oil for 8 weeks followed by LPS injection. The proinflammatory effect of olive oil was also studied using gavage treatment and IP injection of LPS. Animals fed with HFDs showed an increase in body weight, elevated blood glucose levels, and fatty liver phenotype. HFDs aggravated the effect of LPS treatment to induce inflammatory response compared to low fat diet (LFD) effect. Following HFD supplementation, LPS induced hyperinsulinemia, more liver damage than in animals that consumed LFD. In addition, both gavage and long-term feeding with high lipids in the presence of LPS resulted in inhibition of gluconeogenic genes expression.

CONCLUSION

HFDs of both monounsaturated and saturated fat potentiated liver inflammation induced by LPS treatment indicate that the total amount of fat consumed is the main proinflammatory factor rather than the type of fat.

Survival benefit of a low ratio of visceral to subcutaneous adipose tissue depends on LDL clearance versus production in sepsis

Background

Patients with sepsis with a high ratio of visceral adipose tissue (VAT) to subcutaneous adipose tissue (SAT) have increased mortality. Our goal was to investigate the mechanism of this effect, noting that low LDL levels are also associated with increased sepsis mortality. Accordingly we tested for association between VAT/SAT, low-density lipoprotein (LDL) levels, and mortality. Then we examined the effect of statin treatment, which decreases LDL production, and the effect of PCSK9 genotype, which increases LDL clearance.

Methods

We performed retrospective analysis of a cohort of patients with sepsis from a tertiary care adult intensive care unit in Vancouver, Canada, who underwent abdominal computed tomography (CT) (n = 75) for clinical reasons. We compared LDL levels in patients with sepsis according to high versus low VAT/SAT and 90-day survival. We next examined the effects of statin therapy and PCSK9 loss-of-function genotype on survival.

Results

Patients with a low VAT/SAT had increased 90-day survival and were relatively protected against low LDL levels in sepsis compared to high VAT/SAT. Statin treatment abrogated the beneficial effects of low VAT/SAT; eliminating the difference in LDL levels and survival between patients with low and high VAT/SAT. PSCK9 loss-of-function genotype similarly eliminated the increased LDL levels in low VAT/SAT patients but, in contrast, increased the survival advantage of low VAT/SAT compared to high VAT/SAT.

Conclusions

Low LDL levels per se are not simply associated with decreased sepsis survival because lowering LDL levels by inhibiting LDL production (statin treatment) is associated with adverse outcomes, while increased LDL clearance (PCSK9 loss-of-function genotype) is associated with improved outcomes in patients with low VAT/SAT.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-1985-1) contains supplementary material, which is available to authorized users.

Outcomes and Resource Use Among Overweight and Obese Children With Sepsis in the Pediatric Intensive Care Unit

OBJECTIVE

To evaluate the effect of overweight and obesity on outcomes and resource use among patients with sepsis in the pediatric intensive care unit (PICU).

DESIGN

Retrospective analysis of clinical characteristics, resource use, and mortality among children 0 to 20 years of age admitted to the C.S. MottChildren's Hospital PICU (University of Michigan) between January 2009 and December 2015, with a diagnostic code for sepsis at admission (based on International Classification of Diseases, Ninth Revision-Clinical Modification codes) and with weight and height measurements at PICU admission.

MEASUREMENTS AND MAIN RESULTS

A total of 454 participants met the inclusion criteria. Seventy-six were categorized as underweight (body mass index [BMI] percentile <5th) and were excluded, which left a final sample size of 378 participants. Children with a BMI >5th and <85th percentiles for age were categorized as normal weight and those with a BMI >85th percentile as overweight/obese. After descriptive and bivariate analyses, multivariate regression methods were used to assess the independent effect of obesity status on mortality and the use of PICU technology after adjustment for patient age and illness severity at admission. Of the 378 patients studied, 41.3% were overweight/obese. There was no difference in microbiologic etiology of sepsis (P = .36), median PICU length of stay in days (5.4 vs 5.6; P = .61), or PICU mortality (6.4% vs 7.2%; P = .76) by weight status. The use of specialized PICU technology including extracorporeal membrane oxygenation (odds ratio [OR]: 2.77, 95% confidence interval [CI]:1.13-6.79) and continuous renal replacement therapy (OR: 4.58, 95% CI: 1.16-18.0) was higher among overweight/obese patients, compared with normal weight patients.

CONCLUSIONS

Although PICU mortality and length of stay were similar for obese-overweight patients and normal weight critically ill children with sepsis, there was significantly higher use of specialized organ-supportive technology among obese patients, likely indicating higher occurrence of multiple organ dysfunction.

Diabetes Mellitus and Sepsis: A Challenging Association

Sepsis is a life-threatening organ dysfunction caused by a deregulated host response to infection. This inappropriate response to micro-organism invasion is characterized by an overwhelmed systemic inflammatory response and cardiovascular collapse that culminate in high mortality and morbidity in critical care units. The occurrence of sepsis in diabetes mellitus (DM) patients has become more frequent, as the prevalence of DM has increased dramatically worldwide. These two important diseases represent a global public health concern and highlight the importance of increasing our knowledge of the key elements of the immune response related to both conditions. In this context, it is well established that the cells taking part in the innate and adaptive immune responses in diabetic patients have compromised function. These altered responses favor micro-organism growth, a process that contributes to sepsis progression. The present review provides an update on the characteristics of the immune system in diabetic and septic subjects. We also explore the beneficial effects of insulin on the immune response in a glycemic control-dependent and independent manner.

The role of increased body mass index in outcomes of sepsis: a systematic review and meta-analysis

Background

The role of increased body mass index (BMI) in sepsis is controversial. We aimed to evaluate the associations between overweight (25 kg/m² < BMI ≤ 29.9 kg/m²), obese (30 kg/m² < BMI ≤ 39.9 kg/m²) and morbidly obese (BMI > 40 kg/m²) BMIs and outcomes in septic patients.

Methods

We searched the PubMed, Embase, Web of Science, Cochrane Library and ClinicalTrials.gov databases for studies published by December 1, 2016. Electronic database searches yielded 3713 articles, eight of which were included in this meta-analysis. Data were independently extracted by two reviewers, and a third reviewer participated in making decisions as needed. We used Review Manager to conduct the analysis, and the outcomes were reported with odds ratios (ORs) or mean differences (MDs). The primary outcome was mortality, and the secondary outcome was length of stay (LOS) in the intensive care unit (ICU) or the hospital.

Results

Data from eight studies involving a total of 9696 patients were pooled in our final analysis. Compared with patients with normal BMI (18.5 kg/m² < BMI ≤ 24.9 kg/m²), patients with BMI ≥ 25 kg/m² exhibited decreased mortality (OR 0.81; 95% confidence interval (CI), 0.74–0.89, P < 0.0001). In subgroup analysis, compared with normal-weight patients, overweight patients had lower mortality (OR 0.87; 95% CI 0.77–0.97, P = 0.02), whereas obese (OR 0.89, 95% CI 0.72–1.10, P = 0.29) and morbidly obese (OR 0.64, 95% CI 0.38–1.08, P = 0.09) patients did not exhibit significantly reduced mortality.

Conclusions

In sepsis cases, overweight, but not obesity or morbid obesity, was associated with lower mortality. Further prospective studies are needed to clarify this relationship.

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-017-0405-4) contains supplementary material, which is available to authorized users.

The relationship between adiposity and bone density in U.S. children and adolescents

Objective

In adults, obesity has been associated with several health outcomes including increased bone density. Our objective was to evaluate the association between percent body fat and fat mass with bone mineral density (BMD) in a nationally representative population of children and adolescents.

Study design

A total of 8,348 participants 8–18 years of age from the National Health and Nutrition Examination Survey (NHANES) 1999–2006 had whole body DXA scans performed. We conducted linear regressions to examine the relationship between percent body fat and fat mass with outcome variables of total body, pelvic and lumbar spine areal BMD (aBMD), controlling for lean body mass and assessing for gender and race/ethnicity interactions.

Results

We found evidence of gender and race/ethnicity interactions with percent body fat and total fat mass for the different BMD areas. Generally, there were decreases in total body aBMD (p<0.001) and lumbar spine aBMD (p<0.001) with increasing percent body fat and total fat mass, with less consistent patterns for pelvic aBMD.

Conclusion

Our findings of regional differences in the relationship of adiposity to aBMD in children and adolescents with significant interactions by gender and race/ethnicity emphasizes the need for further investigations to understand the impact of adiposity on bone health outcomes.

Short-Term Dietary Restriction Rescues Mice From Lethal Abdominal Sepsis and Endotoxemia and Reduces the Inflammatory/Coagulant Potential of Adipose Tissue

OBJECTIVES

Visceral adipose tissue is a major site for expression of proinflammatory and procoagulant genes during acute systemic inflammation. In this study, we tested whether the loss of fat mass by dietary restriction would remove the major source of these factors resulting in improved tolerance to sepsis and endotoxemia.

DESIGN

Prospective, laboratory controlled experiments.

SETTING

Aging and critical care research laboratory in a university hospital.

SUBJECTS

Middle-aged (12-month old) male C57BL/6 mice.

INTERVENTIONS

Mice were subjected to 40% dietary restriction for 3 weeks followed by induction of abdominal sepsis or endotoxemia by intraperitoneal injection with cecal slurry or lipopolysaccharide, respectively.

MEASUREMENTS AND MAIN RESULTS

Compared with freely fed mice, dietary restricted mice exhibited dramatically improved survival (80% vs 0% after sepsis; p < 0.001 and 86% vs 12% after endotoxemia; p = 0.013) and significantly reduced visceral fat-derived messenger RNA expression of interleukin-6, thrombospondin-1, plasminogen activator inhibitor-1, and tissue factor, which positively correlated with fat mass. Plasma levels of interleukin-6 were significantly reduced by dietary restriction and correlated with adipose interleukin-6 messenger RNA levels and fat mass (p < 0.001; R = 0.64 and 0.89). In vitro culture of visceral fat explants from naive dietary restricted mice showed significantly reduced interleukin-6 secretion compared with that from freely fed mice in response to lipopolysaccharide. Analysis of major adipose immune cell populations by flow cytometry demonstrated that macrophages were the only cell population reduced by dietary restriction and that CD11c/CD206 (M2-type) and CD11c/CD206 (double negative) macrophages, in addition to T cells, are the major immune cell populations that produce interleukin-6 in middle-aged mice during systemic inflammation.

CONCLUSIONS

Short-term dietary restriction drastically improved the survival outcome of middle-aged mice during both polymicrobial sepsis and sterile endotoxemia. Improved survival was accompanied by a significantly attenuated inflammatory response in adipose tissue, which is likely due to alterations of both fat mass quantity and qualitative changes, including a reduction in macrophage populations.

Increased Ratio of Visceral to Subcutaneous Adipose Tissue in Septic Patients Is Associated With Adverse Outcome

OBJECTIVES

Visceral and subcutaneous adipose tissue may contribute differentially to the septic inflammatory response. Accordingly, we tested the hypothesis that the ratio of visceral to subcutaneous adipose tissue is associated with altered sepsis outcome.

DESIGN

A retrospective analysis from a cohort of sepsis patients admitted between 2004 and 2009.

SETTING

A mixed medical-surgical ICU at St. Paul's Hospital in Vancouver, Canada.

PATIENTS

Patients older than 16 years old who had sepsis and underwent abdominal CT scan (n = 257) for clinical reasons.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We measured the visceral adipose tissue and subcutaneous adipose tissue areas and calculated the visceral adipose tissue-to-subcutaneous adipose tissue ratio. Visceral adipose tissue/subcutaneous adipose tissue was not correlated with body mass index (r = -0.015, p = NS) and therefore provides additional unique information independent of body mass index. Sepsis patients with higher visceral adipose tissue/subcutaneous adipose tissue had greater 90-day mortality than patients with lower visceral adipose tissue/subcutaneous adipose tissue (log-rank test, linear-by linear association p < 0.005). After adjustment for significant covariates using Cox regression, increased visceral adipose tissue/subcutaneous adipose tissue quartile was significantly associated with increased 90-day mortality with hazard ratios of 2.01 (95% CI, 1.01-3.99) for the third visceral adipose tissue/subcutaneous adipose tissue quartile compared with the first quartile and 2.32 (95% CI, 1.15-4.69) for the highest visceral adipose tissue/subcutaneous adipose tissue quartile when compared with the first quartile. Increased mortality for patients with higher visceral adipose tissue/subcutaneous adipose tissue was found for both patients with body mass index less than 25 kg/m (p = 0.004) and for body mass index greater than or equal to 25 kg/m (p = 0.023). Furthermore, we found significantly greater need for mechanical ventilation, renal replacement therapy, and ICU stay in patients in the highest visceral adipose tissue/subcutaneous adipose tissue quartile. The ratio of proinflammatory (interleukin-8) to anti-inflammatory (interleukin-10) plasma cytokine levels was greater in patients with higher visceral adipose tissue/subcutaneous adipose tissue than in those with lower visceral adipose tissue/subcutaneous adipose tissue (p = 0.043).

CONCLUSIONS

Visceral obesity, defined by a high visceral adipose tissue-to-subcutaneous adipose tissue ratio, contributes to adverse outcome in sepsis patients perhaps because of a greater pro- versus anti-inflammatory response.

Sepsis in Special Populations

Sepsis is recognized by the presence of physiologic and laboratory changes that reflect the inflammatory response to infection on cellular and systemic levels. Comorbid conditions, such as cirrhosis, end-stage renal disease, and obesity, alter patients' susceptibility to infection and their response to it once present. Baseline changes in vital signs and chronic medications often mask clues to the severity of illness. The physiologic, hematologic, and biochemical adjustments that accompany pregnancy and the puerperium introduce similar challenges. Emergency providers must remain vigilant for subtle alterations in the expected baseline for these conditions to arrive at appropriate management decisions.

OBESITY AND CRITICAL ILLNESS: INSIGHTS FROM ANIMAL MODELS

Critical illness is a major cause of morbidity and mortality around the world. While obesity is often detrimental in the context of trauma, it is paradoxically associated with improved outcomes in some septic patients. The reasons for these disparate outcomes are not well understood. A number of animal models have been used to study the obese response to various forms of critical illness. Just as there have been many animal models that have attempted to mimic clinical conditions, there are many clinical scenarios that can occur in the highly heterogeneous critically ill patient population that occupies hospitals and intensive care units. This poses a formidable challenge for clinicians and researchers attempting to understand the mechanisms of disease and develop appropriate therapies and treatment algorithms for specific subsets of patients, including the obese. The development of new, and the modification of existing animal models, is important in order to bring effective treatments to a wide range of patients. Not only do experimental variables need to be matched as closely as possible to clinical scenarios, but animal models with pre-existing comorbid conditions need to be studied. This review briefly summarizes animal models of hemorrhage, blunt trauma, traumatic brain injury, and sepsis. It also discusses what has been learned through the use of obese models to study the pathophysiology of critical illness in light of what has been demonstrated in the clinical literature.

Impact of body mass index on clinical outcomes in patients with gram-negative bacteria bloodstream infections

INTRODUCTION

Excess body mass index (BMI) is associated with a higher risk of death in many disease states, yet less is known about the impact of higher BMIs on clinical outcomes of serious bacterial infections. We sought to quantify the risk of all-cause mortality and/or organ failure following Gram negative bacteria bloodstream infections (GNBSI) according to BMI.

MATERIALS AND METHODS

We retrospectively reviewed the charts of patients with confirmed GNBSI who received ≥48 h of active antimicrobial therapy. Composite and component patient outcomes, including hospital mortality and organ failure, were assessed as a function of BMI. Organ failure was defined using modified consensus Surviving Sepsis Campaign definitions. Multi-variate methods were used to control for baseline confounders.

RESULTS

Seventy-six patients met our inclusion criteria, of whom 8 died (10.5%). The majority of GNBSI were Escherichia (41.6%) or Klebsiella species (23.3%). Patients with higher BMI more frequently developed cardiovascular failure (P = 0.032), respiratory failure (P < 0.001), renal failure (P = 0.003), and died (P = 0.009). Multivariate analyses demonstrated that higher BMIs were associated with a greater risk of death and/or organ failure (aOR 1.07, 95% CI 1.01-1.14), respiratory failure (aOR 1.10, 95% CI 1.03-1.17), and renal failure (aOR 1.08, 95% CI 1.01-1.14) after adjusting for relevant covariates.

CONCLUSION

Higher BMIs in patients with GNBSIs were associated with a greater risk of a composite of all-cause mortality and organ failure.

Increased body mass index and adjusted mortality in ICU patients with sepsis or septic shock: a systematic review and meta-analysis

Background

At least 25 % of adults admitted to intensive care units (ICU) in the United States have an overweight, obese or morbidly obese body mass index (BMI). The effect of BMI on adjusted mortality in adults requiring ICU treatment for sepsis is unclear. We performed a systematic review of adjusted all-cause mortality for underweight, overweight, obese and morbidly obese BMIs relative to normal BMI for adults admitted to the ICU with sepsis, severe sepsis, and septic shock.

Method

PubMed, the Cochrane Library, and EMBASE electronic databases were searched through November 18, 2015, without language restrictions. We included studies that reported multivariate regression analyses for all-cause mortality using standard BMI categories for adults admitted to the ICU for sepsis, severe sepsis, and septic shock. Articles were selected by consensus among multiple reviewers. Electronic database searches yielded 10,312 articles, of which six were eligible. Data were extracted by one reviewer and then reviewed by three independent reviewers. For the meta-analyses performed, the adjusted odds ratios (aOR) of mortality were combined using a random-effects model. Risk of bias was assessed using the Newcastle-Ottawa quality assessment scale for cohort studies.

Results

Four retrospective (n = 6609 patients) and two prospective (n = 556) studies met inclusion criteria. Compared to normal BMI, across five studies each, overweight or obese BMIs reduced the adjusted odds ratio (95 % CI) of mortality [aOR] [0.83 (0.75, 0.91) p < 0.001 and 0.82 (0.67, 0.99) p = 0.04, respectively] with low or moderate heterogeneity (I² = 15.7 %, p = 0.31 and I² = 53.0 %, p = 0.07, respectively). Across three studies each, morbidly obese BMI and underweight BMI did not alter aOR [0.90 (0.59, 1.39), p = 0.64; I² = 43.3 %, p = 0.17; and 1.24 (0.79, 1.95), p = 0.35; I² = 15.6 %, p = 0.31 respectively]. Only one study clearly defined how and when height and weight measurements were calculated. Site of underlying infection and illness severity may have favored overweight and obese BMIs.

Conclusions

This is the first meta-analysis to show that overweight or obese BMIs reduce adjusted mortality in adults admitted to the ICU with sepsis, severe sepsis, or septic shock. More rigorous studies that address these limitations are needed to clarify the impact of BMI on sepsis ICU outcomes.

Trial registration

PROSPERO International prospective register of systematic reviews 10.15124/CRD42014010556. Registered on July 11, 2014.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1360-z) contains supplementary material, which is available to authorized users.

Obesity and Mortality, Length of Stay and Hospital Cost among Patients with Sepsis: A Nationwide Inpatient Retrospective Cohort Study

OBJECTIVES

The objective of this study was to examine the association between obesity and all-cause mortality, length of stay and hospital cost among patients with sepsis 20 years of age or older.

MATERIALS AND METHODS

It was a retrospective cohort study. The dataset was the Nationwide Inpatient Sample 2011, the largest publicly available all-payer inpatient care database in the United States. Hospitalizations of sepsis patients 20 years of age or older were included. All 25 primary and secondary diagnosis fields were screened to identify patients with sepsis using International Classification of Diseases, Ninth Revision, Clinical Modification codes. Obesity was the exposure of interest. It was one of the 29 standardized Elixhauser comorbidity measures and readily available in the dataset as a dichotomized variable. The outcome measures were all-cause in-hospital death, length of stay and hospital cost.

RESULTS

After weighting, our sample projected to a population size of 1,763,000, providing an approximation for the number of hospital discharges of all sepsis patients 20 years of age or older in the US in 2011. The overall all-cause mortality rate was 14.8%, the median hospital length of stay was 7 days and the median hospital cost was $15,917. After adjustment, the all-cause mortality was lower (adjusted OR = 0.84; 95% CI = 0.81 to 0.88); the average hospital length of stay was longer (adjusted difference = 0.65 day; 95% CI = 0.44 to 0.86) and the hospital cost per stay was higher (adjusted difference = $2,927; 95% CI = $1,606 to $4,247) for obese sepsis patients as compared to non-obese ones.

CONCLUSION

With this large and nationally representative sample of over 1,000 hospitals in the US, we found that obesity was significantly associated with a 16% decrease in the odds of dying among hospitalized sepsis patients; however it was also associated with greater duration and cost of hospitalization.

Influence of Obesity Diagnosis With Organ Dysfunction, Mortality, and Resource Use Among Children Hospitalized With Infection in the United States

BACKGROUND

Sepsis induces inflammation in response to infection and is a major cause of mortality and hospitalization in children. Obesity induces chronic inflammation leading to many clinical manifestations. Our understanding of the impact of obesity on diseases, such as infection and sepsis, is limited. The objective of this study was to evaluate the association of obesity with organ dysfunction, mortality, duration, and charges during among US children hospitalized with infection.

METHODS

Retrospective study of hospitalizations in children with infection aged 0 to 20 years, using the 2009 Kids' Inpatient Database.

RESULTS

Of 3.4 million hospitalizations, 357 701 were for infection, 5685 of which were reported as obese children. Obese patients had higher rates of organ dysfunction (7.35% vs 5.5%, P < .01), longer hospital stays (4.1 vs 3.5 days, P < .001), and accrued higher charges (US$29 019 vs US$21 200, P < .001). In multivariable analysis, mortality did not differ by obesity status (odds ratio: 0.56, 95% confidence interval: 0.23-1.34), however severity of illness modified the association between obesity status and the other outcomes.

CONCLUSIONS

While there was no difference in in-hospital mortality by obesity diagnosis, variation in organ dysfunction, hospital stay, and hospital charges according to obesity status was mediated by illness severity. Findings from this study have significant implications for targeted approaches to mitigate the burden of obesity on infection and sepsis.

Trends in sepsis incidence and outcomes among people with or without type 2 diabetes mellitus in Spain (2008-2012)

AIMS

There is conflicting evidence on how type 2 diabetes mellitus (T2DM) influences in-hospital mortality (IHM) in sepsis. We aimed to compare trends in outcomes for sepsis in people with or without T2DM in Spain between 2008 and 2012.

METHODS

We identified all cases with any sepsis diagnosis using national hospital discharge data. We evaluated annual incidence rates for sepsis stratified by T2DM status. We calculated IHM and analyzed trends over time. In a multivariate analysis including potential confounding factors, we tested T2DM as an independent factor for IHM.

RESULTS

Overall, 217,280 cases of any-stage sepsis were diagnosed, of whom 50,611 (23.3%) had T2DM. The annual incidence of sepsis increased during the 5-year period (from 76.5 to 113.3cases/10(5) population). The incidence increase was higher for the population with T2DM (from 16.8 to 27.1 cases/10(5) population; 61.3% relative increment). People with T2DM were significantly older (75.8 ± 11.2 years vs. 71.0 ± 16.4 years) and suffered from more coexisting medical conditions. In the univariate analysis, mortality was higher for the population with T2DM only when septic shock was present (53.3% vs. 51.9%; P=0.002). IHM decreased over time both in participants with (from 45.7% to 38.1%) and without T2DM (from 46.1% to 39.5%). After accounting for all other potential confounders, T2DM was significantly associated with a lower IHM (odds ratio=0.88; 95% confidence interval, 0.86-0.90).

CONCLUSIONS

In Spain, the annual increase in sepsis incidence was higher in people with T2DM, but the risk of dying with sepsis during admission was moderately lower in people with T2DM.