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

The surviving sepsis campaign: basic/translational science research priorities

Objectives

Expound upon priorities for basic/translational science identified in a recent paper by a group of experts assigned by the Society of Critical Care Medicine and the European Society of Intensive Care Medicine.

Data sources

Original paper, search of the literature.

Study selection

This study is selected by several members of the original task force with specific expertise in basic/translational science. Data extraction and data synthesis are not available.

Conclusions

In the first of a series of follow-up reports to the original paper, several members of the original task force with specific expertise provided a more in-depth analysis of the five identified priorities directly related to basic/translational science. This analysis expounds on what is known about the question and what was identified as priorities for ongoing research. It is hoped that this analysis will aid the development of future research initiatives.

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.

Differential regulation of macrophage activation by the MIF cytokine superfamily members MIF and MIF-2 in adipose tissue during endotoxemia

Sepsis is a leading cause of death worldwide and recent studies have shown white adipose tissue (WAT) to be an important regulator in septic conditions. In the present study, the role of the inflammatory cytokine macrophage migration inhibitory factor (MIF) and its structural homolog D-dopachrome tautomerase (D-DT/MIF-2) were investigated in WAT in a murine endotoxemia model. Both MIF and MIF-2 levels were increased in the peritoneal fluid of LPS-challenged wild-type mice, yet, in visceral WAT, the proteins were differentially regulated, with elevated MIF but downregulated MIF-2 expression in adipocytes. Mif gene deletion polarized adipose tissue macrophages (ATM) toward an anti-inflammatory phenotype while Mif-2 gene knockout drove ATMs toward a pro-inflammatory phenotype and Mif-deficiency was found to increase fibroblast viability. Additionally, we observed the same differential regulation of these two MIF family proteins in human adipose tissue in septic vs healthy patients. Taken together, these data suggest an inverse relationship between adipocyte MIF and MIF-2 expression during systemic inflammation, with the downregulation of MIF-2 in fat tissue potentially increasing pro-inflammatory macrophage polarization to further drive adipose inflammation.

The Effects of Obesity on Outcome in Preclinical Animal Models of Infection and Sepsis: A Systematic Review and Meta-Analysis

BACKGROUND

Clinical studies suggest obesity paradoxically increases survival during bacterial infection and sepsis but decreases it with influenza, but these studies are observational. By contrast, animal studies of obesity in infection can prospectively compare obese versus nonobese controls. We performed a systematic review and meta-analysis of animal investigations to further examine obesity's survival effect in infection and sepsis.

METHODS

Databases were searched for studies comparing survival in obese versus nonobese controls. We performed a systematic review and meta-analysis of animal investigations to further examine obesity's survival effect in infection and sepsis. Methods. Databases were searched for studies comparing survival in obese versus nonobese animals following bacteria, lipopolysaccharide, or influenza virus challenges.

RESULTS

Twenty-one studies (761 obese and 603 control animals) met the inclusion criteria. Obesity reduced survival in 19 studies (11 significantly) and the odds ratio (95% CI) of survival (0.21(0.13, 0.35); I ² = 64%, p < 0.01p < 0.01p < 0.01) but with high heterogeneity. Obesity reduced survival (1) consistently in both single-strain bacteria- and lipopolysaccharide-challenged studies (n = 6 studies, 0.21(0.13, 0.34); I ² = 64%, p < 0.01p < 0.01) but with high heterogeneity. Obesity reduced survival (1) consistently in both single-strain bacteria- and lipopolysaccharide-challenged studies (n = 6 studies, 0.21(0.13, 0.34); I ² = 64%, p < 0.01p < 0.01) but with high heterogeneity. Obesity reduced survival (1) consistently in both single-strain bacteria- and lipopolysaccharide-challenged studies (n = 6 studies, 0.21(0.13, 0.34); I ² = 64%, p < 0.01p < 0.01) but with high heterogeneity. Obesity reduced survival (1) consistently in both single-strain bacteria- and lipopolysaccharide-challenged studies (n = 6 studies, 0.21(0.13, 0.34); I ² = 64%, p < 0.01p < 0.01p < 0.01) but with high heterogeneity. Obesity reduced survival (1) consistently in both single-strain bacteria- and lipopolysaccharide-challenged studies (n = 6 studies, 0.21(0.13, 0.34); I ² = 31%, p=0.20 and n = 5, 0.22(0.13, 0.36); I ² = 0%, p=0.59, respectively), (2) not significantly with cecal ligation and puncture (n = 4, 0.72(0.08, 6.23); I ² = 75%, p < 0.01), and (3) significantly with influenza but with high heterogeneity (n = 6, 0.12(0.04, 0.34); I ² = 73%, p < 0.01). Obesity's survival effects did not differ significantly comparing the four challenge types (p=0.49). Animal models did not include antimicrobials or glycemic control and study quality was low.

CONCLUSIONS

Preclinical and clinical studies together emphasize the need for prospective studies in patients accurately assessing obesity's impact on survival during severe infection.

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.

Medical Versus Surgical ICU Obese Patient Outcome: A Propensity-Matched Analysis to Resolve Clinical Trial Controversies

OBJECTIVES

To determine the short- and long-term mortality of obese ICU patients following medical as opposed to surgical admission and the relation between obesity and mortality.

DESIGN

Retrospective analysis of prospectively collected data, using a propensity score-matched analysis of patients with medical or surgical admission.

SETTING

One French mixed medical-surgical ICU.

PATIENTS

Critically ill obese patients (body mass index ≥ 30 kg/m) and nonobese patients admitted during a 14-year period.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Seven-hundred ninety-one obese patients and 4,644 nonobese patients were included, 338 (43%) and 2,367 (51%) medical and 453 (57%) and 2,277 (49%) surgical obese and nonobese patients, respectively. Mortality was significantly higher in medical than in surgical obese patients in ICU (25% vs 12%; p < 0.001) and up to 365 days (36% vs 18%; p < 0.001) post ICU admission. One-to-one propensity score matching generated 260 pairs with well-balanced baseline characteristics. After matching on propensity score, mortality was still significantly higher in medical patients both in the ICU (21% vs 13%; p = 0.03) and up to 365 days (30% vs 20%; p = 0.01) post ICU admission. Obesity was not significantly associated with mortality both in univariate analysis (140 obese patients [15%] in the dead group vs 651 [14%] in the alive group; p = 0.72) and multivariate analysis (odds ratio, 1.09 [95% CI, 0.86-1.38]; p = 0.49) after adjustment for Simplified Acute Physiology Score II, age, category of admission, history of cardiac disease, and history of respiratory disease.

CONCLUSIONS

After careful matching, the data suggest that ICU mortality in obese population was higher in the medical group than in the surgical group and remains significantly higher 365 days post ICU admission.

Factors predicting long-term survival of patients with sepsis on arrival at the emergency department: A single-center, observational study

Predicting long-term outcomes after sepsis is important when caring for patients with this condition. The purpose of the present study was to develop models predicting long-term mortality of patients with sepsis, including septic shock.Retrospective data from 446 patients with sepsis (60.8% men; median age, 71 years) treated at a single university-affiliated tertiary care hospital over 3 years were reviewed. Binary logistic regression was used to identify factors predicting mortality at 180 and 365 days after arrival at the emergency department. Long-term prognosis scores for the 180- and 365-day models were calculated by assigning points to variables according to their β coefficients.The 180- and 365-day mortality rates were 40.6% and 47.8%, respectively. Multivariate analysis identified the following factors for inclusion in the 180- and 365-day models: age ≥65 years, body mass index ≤18.5 kg/m, hemato-oncologic diseases as comorbidities, and ventilator care. Patients with scores of 0 to ≥3 had 180-day survival rates of 83.8%, 70.8%, 42.3%, and 25.0%, respectively, and 365-day survival rates of 72.1%, 64.6%, 36.2%, and 15.9%, respectively (all differences P < .001; log-rank test). The areas under the receiver operating characteristic curves of the 180- and 365-day models were 0.713 (95% confidence interval [CI] 0.668-0.756, P < .001) and 0.697 (95% CI 0.650-0.740, P < .001), respectively.These long-term prognosis models based on baseline patient characteristics and treatments are useful for predicting the 6- and 12-month mortality rates of patients with sepsis.

Combination of red blood cell distribution width and body mass index (COR-BMI) predicts in-hospital mortality in patients with different diagnoses?

Background

The combination of red blood cell distribution width and body mass index (COR-BMI) is indicated as a new prognostic index of survival in patients with laryngeal cancer. However, the ability of this prediction in other types of cancer or whether its use can be expanded to non-oncological patients is unknown. The aim of this study was to investigate the prediction of prognosis of in-hospital mortality of the COR-BMI in oncological and non-oncological patients.

Methods

A retrospective study was performed with all hospitalized patients between 2014 and 2016, totaling 2930 patients, 262 oncological and 2668 non-oncological. The COR-BMI was divided into three classes: 0, RDW ≤ 13.1% and BMI ≥ 25 kg/m²; 1, RDW ≤ 13.1% and BMI < 18.5 or ≥ 18.5 but < 25 kg/m² and RDW > 13.1% and BMI ≥ 18.5 but < 25 or BMI ≥ 25 kg/m²; and 2, RDW > 13.1% and BMI < 18.5 kg/m². In order to analyze the relationship between COR-BMI and in-hospital mortality in the studied population, the Cox Proportional Hazards Model was used in a multivariate analysis based on a conceptual model.

Results

The COR-BMI was an independent predictor of in-hospital mortality in non-oncological patients (1 versus 0: HR = 3.34; CI = 1.60–6.96, p = 0.001; 2 versus 0: HR = 3.38; CI = 1.22–9.39, p = 0.019). The survival rate of these patients was lower among those with the highest scores on the COR-BMI. This prediction was not found in oncological patients.

Conclusion

The present study suggests that the COR-BMI may have its practical use expanded to non-oncological patients as an independent predictor of in-hospital mortality.

Risk factors associated with the development of sepsis after reconstructive flap surgery. J Plast Surg Hand Surg 2019;53:328-334. [PMID: 31204583 DOI: 10.1080/2000656x.2019.1626738]

Sepsis is a serious and potentially life-threatening condition. Risk factors that are associated with the development of sepsis may differ as it relates to reconstructive flap surgery. The purpose of this study is to identify the incidence and predictors for sepsis in patients undergoing reconstructive flap surgery. The ACS-NSQIP database was queried from 2005 to 2016 for factors related to sepsis in patients undergoing reconstructive flap surgery. CPT codes were used to identify patient cohorts. A sepsis group was compared to a control group that underwent the same procedures without the postoperative manifestations of sepsis. Statistical analyses were performed to ascertain risk factors associated with the development of sepsis. 24,257 patients who underwent flap reconstruction were included in this study. Of these, 511 developed sepsis postoperatively (2.1%). Multivariate analysis showed that male gender (p < .001), African-American race (p < .001), hypertension requiring medication (p < .001), smoking (p < .001), a higher Charlson comorbidity Index score (p < .001), evidence of preoperative wound infection (p < .001), chronic steroid use (p < .001), and prolonged operative time (p < .001) all significantly were associated with the development of sepsis. Sepsis resulted in a higher chance of 30-day mortality (p < .001) and increased the risk of developing septic shock (OR: 2.578, CI: 1.241-5.354) This study shows that postoperative sepsis is a serious complication of reconstructive flap surgery. Risk reduction and prevention of potentially life-threatening complications is always a priority. Awareness of the risk factors contributing to the development of sepsis is crucial for early intervention and treatment.

Lifestyle risk factors, obesity and infectious disease mortality in the general population: Linkage study of 97,844 adults from England and Scotland

We examined associations between lifestyle variables and infectious disease mortality in a large general population cohort. A sample of 97,844 men and women (aged 47.1 ± 17.7 yrs.; 46.6% male) recruited from general population, household-based surveys were followed up over mean [SD] 9.4 ± 4.5 years. Exposure measurements included self-reported physical activity, cigarette smoking, alcohol intake, and objective body mass index and waist to hip ratio. There were 9027 deaths, of which 14.1% were attributed to infectious diseases. Compared to physically inactive participants both insufficiently active (Hazard ratio = 0.61; 95% CI, 0.50, 0.75) and sufficiently active (at least 150 min/wk. moderate - vigorous activity) (0.60; 0.45, 0.78) was associated with reduced risk of infectious disease mortality in models mutually adjusted for other lifestyle factors. Ex-smokers and current smokers were at increased risk of infectious disease mortality compared with never smoker, with the strongest associations being observed for heavy smoking (>20 cigarettes/day) and pneumonia (3.30; 2.35, 4.63). Underweight was associated with increased risk of infectious disease mortality (3.65; 2.64, 5.06) compared with normal weight; the risk of viral infection was lower in overweight (0.56; 0.44, 0.72) and obesity (0.39; 0.26, 0.58). Central obesity was, however, related to higher risk of bacterial infections, but only in normal weight centrally obese participants (1.71; 1.10, 2.64). A physically active lifestyle and lifelong absence from cigarette smoking had protective associations against infectious disease mortality. Obesity has divergent associations dependent on peripheral and visceral fat depots, and the specific outcome.

Impact of body mass index on survival of medical patients with sepsis: a prospective cohort study in a university hospital in China

OBJECTIVE

To evaluate the impact of body mass index (BMI) on survival of a Chinese cohort of medical patients with sepsis.

DESIGN

A single-centre prospective cohort study conducted from May 2015 to April 2017.

SETTING

A tertiary care university hospital in China.

PARTICIPANTS

A total of 178 patients with sepsis admitted to the medical intensive care unit (ICU) were included.

MAIN OUTCOME MEASURES

The primary outcome was 90-day mortality while the secondary outcomes were in-hospital mortality, length of ICU stay and length of hospital stay.

RESULTS

The median age (IQR) was 78 (66-84) years old, and 77.0% patients were older than 65 years. The 90-day mortality was 47.2%. The in-hospital mortality was 41.6%, and the length of ICU stay and hospital stay were 12 (5-22) and 15 (9-28) days, respectively. Cox proportional hazard regression analysis identified that Sequential Organ Failure Assessment score (HR=1.229, p<0.001), Acute Physiology and Chronic Health Evaluation II score (HR=1.050, p<0.001) and BMI (HR=0.940, p=0.029) were all independently associated with the 90-day mortality. Patients were divided into four groups based on BMI (underweight 33 (18.5%), normal 98 (55.1%), overweight 36 (20.2%) and obese 11 (6.2%)). The 90-day mortality (66.7%, 48.0%, 36.1% and 18.2%, p=0.015) and in-hospital mortality (60.6%, 41.8%, 30.6% and 18.2%, p=0.027) were statistically different among the four groups. Differences in survival among the four groups were demonstrated by Kaplan-Meier survival analysis (p=0.008), with the underweight patients showing a lower survival rate.

CONCLUSIONS

BMI was an independent factor associated with 90-day survival in a Chinese cohort of medical patients with sepsis, with patients having a lower BMI at a higher risk of death.

The obesity conundrum in sepsis

While the long-term negative effects of obesity on health is a well-studied phenomenon, its effects on acute illnesses seem to be the contrary. Several studies have indicated the possibility of an 'obesity paradox' in sepsis - where overweight and obese patients have better outcomes than normal weight patients. These meta-analyses including large numbers of patients across different countries raised an interesting but debatable topic. Results from meta-analyses of observational studies should be interpreted with caution, and a prove of association not be mistaken as prove of causality. Limitations common to such studies include inadequate adjustment for confounding and selection bias. More rigorous investigations to clarify any causal relationship between obesity and mortality in sepsis are needed.