The paradox prevails: Outcomes are better in critically ill obese patients regardless of the comorbidity burden

Role of obesity in pathogenesis of acute pancreatitis

Acute pancreatitis (AP) is one of the most common digestive disorders that cause hospitalization. While most of patients with AP have a mild to moderate disease and recover rapidly, about 20% of patients with AP have a severe disease and experience substantial morbidity and mortality from local and/or systemic compli-cations. The incidence of obesity has increased worldwide, and its epidemiological characteristics and rising trend are consistent with those of AP. Therefore, obesity has probably contributed to the increase in the incidence and severity of AP. However, previous studies have generated conflicting results, and some studies demonstrated that obesity is a protective factor in patients with AP. Here we discuss the role of obesity in the pathogenesis of AP and the underlying mechanisms based on clinically relevant studies.

The impact of body mass index on long-term survival after ICU admission due to COVID-19: A retrospective multicentre study

Objective

The impact of obesity on long-term survival after intensive care unit (ICU) admission with severe coronavirus disease 2019 (COVID-19) is unclear. We aimed to quantify the impact of obesity on time to death up to two years in patients admitted to Australian and New Zealand ICUs.

Design

Retrospective multicentre study.

Setting

92 ICUs between 1st January 2020 through to 31st December 2020 in New Zealand and 31st March 2022 in Australia with COVID-19, reported in the Australian and New Zealand Intensive Care Society adult patient database.

Participants

All patients with documented height and weight to estimate the body mass index (BMI) were included. Obesity was classified patients according to the World Health Organization recommendations.

Interventions and main outcome measures

The primary outcome was survival time up to two years after ICU admission. The effect of obesity on time to death was assessed using a Cox proportional hazards model. Confounders were acute illness severity, sex, frailty, hospital type and jurisdiction for all patients.

Results

We examined 2,931 patients; the median BMI was 30.2 (IQR 25.6-36.0) kg/m2. Patients with a BMI ≥30 kg/m2 were younger (median [IQR] age 57.7 [46.2-69.0] vs. 63.0 [50.0-73.6]; p < 0.001) than those with a BMI <30 kg/m2. Most patients (76.6%; 2,244/2,931) were discharged alive after ICU admission. The mortality at two years was highest for BMI categories <18.5 kg/m2 (35.4%) and 18.5-24.9 kg/m2 (31.1%), while lowest for BMI ≥40 kg/m2 (14.5%). After adjusting for confounders and with BMI 18.5-24.9 kg/m2 category as a reference, only the BMI ≥40 kg/m2 category patients had improved survival up to 2 years (hazard ratio = 0.51; 95%CI: 0.34-0.76).

Conclusions

The obesity paradox appears to exist beyond hospital discharge in critically ill patients with COVID-19 admitted in Australian and New Zealand ICUs. A BMI ≥40 kg/m2 was associated with a higher survival time of up to two years.

Body mass index does not impact survival in COVID-19 patients requiring veno-venous extracorporeal membrane oxygenation

INTRODUCTION

With the increased demand for veno-venous extracorporeal membrane oxygenation (VV ECMO) during the COVID-19 pandemic, guidelines for patient candidacy have often limited this modality for patients with a body mass index (BMI) less than 40 kg/m2. We hypothesize that COVID-19 VV ECMO patients with at least class III obesity (BMI ≥ 40) have decreased in-hospital mortality when compared to non-COVID-19 and non-class III obese COVID-19 VV ECMO populations.

METHODS

This is a single-center retrospective study of COVID-19 VV ECMO patients from January 1, 2014, to November 30, 2021. Our institution used BMI ≥ 40 as part of a multi-disciplinary VV ECMO candidate screening process in COVID-19 patients. BMI criteria were not considered for exclusion criteria in non-COVID-19 patients. Univariate and multivariable analyses were performed to assess in-hospital mortality differences.

RESULTS

A total of 380 patients were included in our analysis: The COVID-19 group had a lower survival rate that was not statistically significant (65.7% vs.74.9%, p = .07). The median BMI between BMI ≥ 40 COVID-19 and non-COVID-19 patients was not different (44.5 vs 45.5, p = .2). There was no difference in survival between the groups (73.3% vs. 78.5%, p = .58), nor was there a difference in survival between the COVID-19 BMI ≥ 40 and BMI < 40 patients (73.3, 62.7, p= .29). Multivariable logistic regression with the outcome of in-hospital mortality was performed and BMI was not found to be significant (OR 0.99, 95% CI 0.89, 1.01; p = .92).

CONCLUSION

BMI ≥ 40 was not an independent risk factor for decreased in-hospital survival in this cohort of VV ECMO patients at a high-volume center. BMI should not be the sole factor when deciding VV ECMO candidacy in patients with COVID-19.

The Impact of Body Mass Index on In-Hospital Mortality in Post-Cardiac-Arrest Patients-Does Sex Matter?

BACKGROUND

A number of factors influence mortality in post-cardiac-arrest (CA) patients, nutritional status being one of them. The aim of this study was to assess whether there are sex differences in the prognostic impact of BMI, as calculated on admission to an intensive care unit, on in-hospital mortality in sudden cardiac arrest (SCA) survivors.

METHODS

We carried out a retrospective analysis of data of 129 post-cardiac-arrest patients with return of spontaneous circulation (ROSC) admitted to the Intensive Care Unit (ICU) of the University Teaching Hospital in Wrocław between 2017 and 2022.

RESULTS

Female patients were significantly older than male patients (68.62 ± 14.77 vs. 62.7 ± 13.95). The results of univariable logistic regression analysis showed that BMI was not associated with the odds of in-hospital death in either male or female patients. In an age-adjusted model, age was an independent predictor of the odds of in-hospital death only in male patients (OR = 1.034). In our final multiple logistic regression model, adjusted for the remaining variables, none of the traits analysed were a significant independent predictor of the odds of in-hospital death in female patients, whereas an initial rhythm of ventricular fibrillation or pulseless ventricular tachycardia (VF/pVT) was an independent predictor of the odds of in-hospital death in male patients (OR = 0.247).

CONCLUSIONS

BMI on admission to ICU is not a predictor of the odds of in-hospital death in either male or female SCA survivors.

Ramping Position to Aid Non-invasive Ventilation (NIV) in Obese Patients in the ICU

Introduction

The ramping position is recommended to facilitate pre-oxygenation and mask ventilation of obese patients in anaesthetics via improving the airway alignment.

Presentation of case series

Two cases of obese patients admitted to the intensive care unit (ICU) with type 2 respiratory failure. Both cases showed obstructive breathing patterns on non-invasive ventilation (NIV) and failed resolution of hypercapnia. Ramping position alleviated the obstructive breathing pattern and hypercapnia was subsequently resolved.

Conclusion

There are no available studies on the rule of the ramping position in aiding NIV in obese patients in the ICU. Accordingly, this case series is significantly important in highlighting the possible benefits of the ramping position for obese patients in settings other than anaesthesia.

Mortality risk in patients with underweight or obesity with peripheral artery disease: a meta-analysis including 5,735,578 individuals

OBJECTIVES

The "obesity paradox" - in which patients with obesity exhibit superior survival than normal-weight counterparts - has been reported for several diseases. However, obesity is a well-known risk factor for cardiovascular disease, and whether the obesity paradox is present in peripheral artery disease (PAD) is unknown.

METHODS

A comprehensive search for studies that reported mortality in patients with PAD grouped by BMI identified 12 studies. We compared the survival of underweight patients with those who were not underweight, and patients with obesity against those without. Underweight was defined by a BMI value of <18.5 kg/m² in most studies and obesity by BMI ≥ 30 kg/m². Subgroup analyses were performed according to length of follow-up, presentation of PAD, and mode of revascularization. Meta-regression analyses were conducted, with covariates including age, sex, presence of coronary artery disease (CAD) and diabetes mellitus (DM).

RESULTS

The mortality risk of underweight patients with PAD was significantly higher compared to those who are not underweight (HR 1.72, 95% CI 1.38-2.14; I² = 84.2%). In contrast, the mortality risk of patients with obesity with PAD was significantly lower than those without (HR 0.78, 95% CI 0.62-0.97; I² = 89.8%). These findings remained consistent regardless of the presentation of PAD, revascularization, age, sex, or presence of CAD. The risk of death in the short-term of underweight patients (HR 1.50, 95% CI 0.47-4.72) and patients with obesity (HR 0.86, 95% CI 0.66-1.13) were not significantly different from their counterparts. The meta-regression showed that of the association between obesity and better survival was more pronounced in studies with a greater proportion of patients with concomitant CAD (regression coefficient -0.029, 95% CI -0.054 to -0.004).

CONCLUSIONS

In patients with PAD, mortality is higher among underweight patients and lower among patients with obesity. The mechanisms underlying the obesity paradox in patients with PAD remain to be elucidated, and further evidence is required to guide optimal weight control strategies in these patients.

A Dose Response Association Between Body Mass Index and Mortality in Patients with Peripheral Artery Disease: A Meta-analysis Including 5 729 272 Individuals

OBJECTIVE

Obesity is a significant risk factor for atherosclerotic cardiovascular disease; however, the "obesity paradox", in which obese patients enjoy superior survival, has been observed in various cardiovascular conditions. Whether this phenomenon exists for peripheral artery disease (PAD) remains uncertain. The goal of this study was to evaluate the relationship between body mass index (BMI) and mortality in patients with PAD.

METHODS

A comprehensive literature search identified seven eligible cohort studies that reported the association between BMI and all cause mortality in patients with PAD. A dose response meta-analysis was done for all cause mortality, short term (30 day or in hospital) mortality and long term mortality. The dose response association between BMI and mortality was also assessed in patients who received endovascular therapy (EVT).

RESULTS

The non-linear dose response analysis showed that higher BMI values were associated with a lower mortality risk from the range between 15 kg/m² to approximately 33 - 34 kg/m². The risk of mortality increased slightly thereafter. This relationship was consistent with that of long term mortality but was not apparent in short term mortality. A U shaped relationship was also observed between BMI and mortality in patients who received EVT with the lowest mortality observed at around 30 kg/m².

CONCLUSION

The obesity paradox was evident in the analysis of long term survival among patients with PAD, with the lowest mortality rates observed in obese patients. However, this association was not observed for short term or in hospital mortality.

Effect of Body Mass Index on the Clinical Outcomes of Adult Patients Treated With Venoarterial ECMO for Cardiogenic Shock

OBJECTIVE

Current guidelines consider obesity to be a relative contraindication to venoarterial extracorporeal membrane oxygenation (VA-ECMO) for refractory cardiogenic shock. The authors investigated the effect of body mass index (BMI) on clinical outcomes in patients treated with VA-ECMO for cardiogenic shock.

DESIGN

This was a retrospective and observational study.

SETTING

University hospital.

PARTICIPANTS

The study comprised 150 adult patients who underwent VA-ECMO for cardiogenic shock.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was intensive care unit (ICU) mortality. Of the 150 included patients, 10 were underweight (BMI < 18.5 kg/m²), 62 were normal weight (BMI = 18.5-24.9 kg/m²), 34 were overweight (BMI = 25.0-29.9 kg/m²), 34 were obese class I (BMI = 30.0-34.9 kg/m²), and 10 were obese class II (BMI = 35.0-39.9 kg/m²). All-cause ICU mortality was 62% (underweight, 70%; normal weight, 53%; overweight, 65%; class I obese, 71%; class II obese, 70%). After multivariate logistic regression, BMI was not associated with ICU mortality (adjusted odds ratio [aOR] 0.99 [0.92-1.07], p = 0.8). Analysis by BMI category showed unfavorable mortality trends in underweight patients (aOR 3.58 [0.82-19.6], p = 0.11) and class I obese patients (aOR 2.39 [0.95-6.38], p = 0.07). No statistically significant differences were found among BMI categories in the incidences of complications.

CONCLUSION

The results suggested that BMI alone should not be considered an exclusion criterion for VA-ECMO. The unfavorable trend observed in underweight patients could be the result of malnutrition.

BMI and pneumonia outcomes in critically ill covid-19 patients: An international multicenter study

OBJECTIVE

Previous studies have unveiled a relationship between the severity of coronavirus disease 2019 (COVID-19) pneumonia and obesity. The aims of this multicenter retrospective cohort study were to disentangle the association of BMI and associated metabolic risk factors (diabetes, hypertension, hyperlipidemia, and current smoking status) in critically ill patients with COVID-19.

METHODS

Patients admitted to intensive care units for COVID-19 in 21 centers (in Europe, Israel, and the United States) were enrolled in this study between February 19, 2020, and May 19, 2020. Primary and secondary outcomes were the need for invasive mechanical ventilation (IMV) and 28-day mortality, respectively.

RESULTS

A total of 1,461 patients were enrolled; the median (interquartile range) age was 64 years (40.9-72.0); 73.2% of patients were male; the median BMI was 28.1 kg/m² (25.4-32.3); a total of 1,080 patients (73.9%) required IMV; and the 28-day mortality estimate was 36.1% (95% CI: 33.0-39.5). An adjusted mixed logistic regression model showed a significant linear relationship between BMI and IMV: odds ratio = 1.27 (95% CI: 1.12-1.45) per 5 kg/m² . An adjusted Cox proportional hazards regression model showed a significant association between BMI and mortality, which was increased only in obesity class III (≥40; hazard ratio = 1.68 [95% CI: 1.06-2.64]).

CONCLUSIONS

In critically ill COVID-19 patients, a linear association between BMI and the need for IMV, independent of other metabolic risk factors, and a nonlinear association between BMI and mortality risk were observed.

The Impact of Obesity in Critical Illness

The prevalence of obesity is rising worldwide. Adipose tissue exerts anatomic and physiological effects with significant implications for critical illness. Changes in respiratory mechanics cause expiratory flow limitation, atelectasis, and V̇/Q̇ mismatch with resultant hypoxemia. Altered work of breathing and obesity hypoventilation syndrome may cause hypercapnia. Challenging mask ventilation and peri-intubation hypoxemia may complicate intubation. Patients with obesity are at increased risk of ARDS and should receive lung-protective ventilation based on predicted body weight. Increased positive end expiratory pressure (PEEP), coupled with appropriate patient positioning, may overcome the alveolar decruitment and intrinsic PEEP caused by elevated baseline pleural pressure; however, evidence is insufficient regarding the impact of high PEEP strategies on outcomes. Venovenous extracorporeal membrane oxygenation may be safely performed in patients with obesity. Fluid management should account for increased prevalence of chronic heart and kidney disease, expanded blood volume, and elevated acute kidney injury risk. Medication pharmacodynamics and pharmacokinetics may be altered by hydrophobic drug distribution to adipose depots and comorbid liver or kidney disease. Obesity is associated with increased risk of VTE and infection; appropriate dosing of prophylactic anticoagulation and early removal of indwelling catheters may decrease these risks. Obesity is associated with improved critical illness survival in some studies. It is unclear whether this reflects a protective effect or limitations inherent to observational research. Obesity is associated with increased risk of intubation and death in SARS-CoV-2 infection. Ongoing molecular studies of adipose tissue may deepen our understanding of how obesity impacts critical illness pathophysiology.

Obesity and mortality in critically ill COVID-19 patients with respiratory failure

BACKGROUND

Patients with obesity are at increased risk of severe COVID-19, requiring mechanical ventilation due to acute respiratory failure. However, conflicting data are obtained for intensive care unit (ICU) mortality.

OBJECTIVE

To analyze the relationship between obesity and in-hospital mortality of ICU patients with COVID-19.

SUBJECTS/METHODS

Patients admitted to the ICU for COVID-19 acute respiratory distress syndrome (ARDS) were included retrospectively. The following data were collected: comorbidities, body mass index (BMI), the severity of ARDS assessed with PaO₂/FiO₂ (P/F) ratios, disease severity measured by the Simplified Acute Physiology Score II (SAPS II), management and outcomes.

RESULTS

For a total of 222 patients, there were 34 patients (15.3%) with normal BMI, 92 patients (41.4%) who were overweight, 80 patients (36%) with moderate obesity (BMI:30-39.9 kg/m²), and 16 patients (7.2%) with severe obesity (BMI ≥ 40 kg/m²). Overall in-hospital mortality was 20.3%. Patients with moderate obesity had a lower mortality rate (13.8%) than patients with normal weight, overweight or severe obesity (17.6%, 21.7%, and 50%, respectively; P = 0.011. Logistic regression showed that patients with a BMI ≤ 29 kg/m² (odds ratio [OR] 3.64, 95% CI 1.38-9.60) and those with a BMI > 39 kg/m² (OR 10.04, 95% CI 2.45-41.09) had a higher risk of mortality than those with a BMI from 29 to 39 kg/m². The number of comorbidities (≥2), SAPS II score, and P/F < 100 mmHg were also independent predictors for in-hospital mortality.

CONCLUSIONS

COVID-19 patients admitted to the ICU with moderate obesity had a lower risk of death than the other patients, suggesting a possible obesity paradox.

End-Stage Renal Disease Patients on Chronic Hemodialysis Fare Better With COVID-19: A Retrospective Cohort Study From the New York Metropolitan Region

Introduction

Several comorbid conditions have been identified as risk factors in patients with coronavirus disease 2019 (COVID-19). However, there is a dearth of data describing the impact of COVID-19 infection in patients with end-stage renal disease on hemodialysis (ESRD-HD).

Methods

This retrospective case series analyzed 362 adult patients consecutively hospitalized with confirmed COVID-19 illness between March 12, 2020, and May 13, 2020, at a teaching hospital in the New York City metropolitan area. The primary outcome was severe pneumonia as defined by the World Health Organization. Secondary outcomes were the (1) the Combined Outcome of Acute respiratory distress syndrome or in-hospital Death (COAD), and (2) need for high levels of oxygen supplementation (HiO₂).

Results

Patients with ESRD-HD had lower odds for poor outcomes including severe pneumonia [odds ratio (OR) 0.4, confidence interval (CI) 0.2-0.9, p=.04], HiO₂ [OR 0.3, CI (0.1-0.8), p=.02] and COAD [OR 0.4, CI (0.2-1.05), p=.06], when compared to patients without ESRD. In contrast, higher odds for severe pneumonia, COAD and HiO₂ were seen with advancing age. African Americans were over-represented in the hospitalized patient cohort, when compared to their representation in the community (35% vs 18%). Hispanics had higher odds for severe illness and HiO₂ when compared to Caucasians.

Conclusions

Patients with ESRD-HD had a milder course of illness with a lower likelihood of severe pneumonia and a lesser need for aggressive oxygen supplementation when compared to patients not on chronic dialysis. The lower odds of severe illness in ESRD-HD patients might have a pathophysiologic basis and need to be further explored.

Is There an Obesity Paradox in Critical Illness? Epidemiologic and Metabolic Considerations

PURPOSE OF REVIEW

Obesity represents a global epidemic with serious implications in public health due to its increasing prevalence and its known association with a high morbidity and mortality burden. However, a growing number of data support a survival benefit of obesity in critical illness. This review summarizes current evidence regarding the obesity paradox in critical illness, discusses methodological issues and metabolic implications, and presents potential pathophysiologic mechanisms.

RECENT FINDINGS

Data from meta-analyses and recent studies corroborate the obesity-related survival benefit in critically ill patients as well as in selected populations such as patients with sepsis and acute respiratory distress syndrome, but not trauma. However, this finding warrants a cautious interpretation due to certain methodological limitations of these studies, such as the retrospective design, possible selection bias, the use of BMI as an obesity index, and inadequate adjustment for confounding variables. Main pathophysiologic mechanisms related to obesity that could explain this phenomenon include higher energy reserves, inflammatory preconditioning, anti-inflammatory immune profile, endotoxin neutralization, adrenal steroid synthesis, renin-angiotensin system activation, cardioprotective metabolic effects, and prevention of muscle wasting. The survival benefit of obesity in critical illness is supported from large meta-analyses and recent studies. Due to important methodological limitations, more prospective studies are needed to further elucidate this finding, while future research should focus on the pathophysiologic role of adipose tissue in critical illness.

Dietary management of blood glucose in medical critically ill patients with overweight/obesity

PURPOSE OF REVIEW

As the obesity epidemic continues, there is a greater proportion of patients with overweight, obesity, and other forms of adiposity-based chronic disease that require intensive care. Nutrition therapy in the ICU is a vital part of critical care but can be challenging in this setting because of the increased risk of stress hyperglycemia and adverse impact of obesity- and diabetes-related complications.

RECENT FINDINGS

Current guidelines favor early nutritional therapy with a hypocaloric, high-protein diet in patients with overweight/obesity. More aggressive protein intake may be useful in those with greater severity of overweight/obesity with an upper limit of 3 g/kg ideal body weight per day. Although there is no specific recommendation, choosing enteral formulas with higher fat content and slower digesting carbohydrates may assist with glucose control. Supplementation with immunonutrients is recommended, given their known benefits in obesity and in reducing inflammation, but must be done in an individualized manner.

SUMMARY

Aggressive nutritional therapy is crucial in patients with overweight/obesity to support ongoing metabolic demands. Although a hypocaloric high-protein feeding strategy is a starting point, nutritional therapy should be approached in an individualized manner taking into account age, weight and BMI, basal metabolism, nutrition status, complications, and comorbidities.