Predictive value of abdominal obesity vs. body mass index for determining risk of intensive care unit mortality:

Association between sagittal abdominal diameter-to-height ratio and all-cause mortality among adults in the United States: a longitudinal study

BACKGROUND

The global health crisis of obesity has prompted a need for better indicators of abdominal obesity than body mass index, with sagittal abdominal diameter emerging as a potential candidate. Nonetheless, the association between sagittal abdominal diameter-to-height ratio (SADHtR) and mortality remains inadequately established. Our objective was to contribute novel evidence to this association.

METHODS

This study encompassed 12,572 participants aged 18-80 years from the National Health and Nutrition Examination Survey 2011-2016. Mortality data were tracked until December 31, 2019. Weighted multivariable Cox proportional hazard models were employed to evaluate the association between SADHtR and all-cause mortality, with subgroup analyses conducted for result robustness.

RESULTS

Following a median follow-up period of 69 months, each standard deviation (SD) increase in SADHtR was consistently associated with a higher risk of all-cause mortality across three models, yielding a hazard ratio (HR) and 95% confidence interval (CI) of 1.51(1.29,1.76) in model 3. Additionally, compared to the first tertile of SADHtR, the third tertile exhibited a higher risk for all-cause mortality, with HRs(95%CIs) of 1.58(1.25,2.01) in model 1, 2.01(1.33,3.02) in model 2, and 1.74(1.19,2.57) in model 3. Notably, subgroup analysis revealed persistent positive associations between SADHtR and all-cause mortality among subgroups based on age-at-risk (< 65, ≥ 65 years), sex, diabetes, hypertension, and hyperlipidemia.

CONCLUSIONS

Elevated SADHtR was consistently associated with a higher risk of all-cause mortality in American adults. Regular SADHtR measurement should be considered to be integrated into clinical practice and healthcare examinations.

Adiposity and mortality among intensive care patients with COVID-19 and non-COVID-19 respiratory conditions: a cross-context comparison study in the UK

BACKGROUND

Adiposity shows opposing associations with mortality within COVID-19 versus non-COVID-19 respiratory conditions. We assessed the likely causality of adiposity for mortality among intensive care patients with COVID-19 versus non-COVID-19 by examining the consistency of associations across temporal and geographical contexts where biases vary.

METHODS

We used data from 297 intensive care units (ICUs) in England, Wales, and Northern Ireland (Intensive Care National Audit and Research Centre Case Mix Programme). We examined associations of body mass index (BMI) with 30-day mortality, overall and by date and region of ICU admission, among patients admitted with COVID-19 (N = 34,701; February 2020-August 2021) and non-COVID-19 respiratory conditions (N = 25,205; February 2018-August 2019).

RESULTS

Compared with non-COVID-19 patients, COVID-19 patients were younger, less often of a white ethnic group, and more often with extreme obesity. COVID-19 patients had fewer comorbidities but higher mortality. Socio-demographic and comorbidity factors and their associations with BMI and mortality varied more by date than region of ICU admission. Among COVID-19 patients, higher BMI was associated with excess mortality (hazard ratio (HR) per standard deviation (SD) = 1.05; 95% CI = 1.03-1.07). This was evident only for extreme obesity and only during February-April 2020 (HR = 1.52, 95% CI = 1.30-1.77 vs. recommended weight); this weakened thereafter. Among non-COVID-19 patients, higher BMI was associated with lower mortality (HR per SD = 0.83; 95% CI = 0.81-0.86), seen across all overweight/obesity groups and across dates and regions, albeit with a magnitude that varied over time.

CONCLUSIONS

Obesity is associated with higher mortality among COVID-19 patients, but lower mortality among non-COVID-19 respiratory patients. These associations appear vulnerable to confounding/selection bias in both patient groups, questioning the existence or stability of causal effects.

Obesity: A Review of Pathophysiology and Classification

Obesity is a chronic, multifactorial, and morbid disease. In the United States, 69% of adults are overweight or have obesity, and the global prevalence of obesity is increasing. Obesity is influenced by genetic, neurologic, metabolic, enteric, and behavioral processes. It remains a key modifiable risk factor for many comorbid diseases, including cardiovascular disease, diabetes mellitus, and cancer. Whereas there are recent and significant advances in obesity therapy, including diets, lifestyle modifications, pharmacotherapies, endoscopic procedures, and bariatric surgeries, there is an immense need for a better understanding of the heterogeneity in the pathophysiologic process of obesity and outcomes. Here we review salient pathophysiologic mechanisms underlying the development and morbidity of obesity as well as pathophysiologically based classification systems that inform current obesity management and may inform improved and individualized management in the future.

Body mass index as a predictor of the outcomes of acute clozapine toxicity: a cross-sectional study

Acute antipsychotic overdose is frequently reported nowadays. Clozapine is one of the atypical agents that are highly lipophilic, highly protein-bound, has a large volume of distribution, and accumulates in the brain and other tissues. Obesity is an essential factor controlling patients' treatment and clinical course. The current study aimed to study the prognostic value of body mass index (BMI) in patients with acute clozapine poisoning. All patients were evaluated on admission using the Poison Severity Score (PSS) and Glasgow Coma Score (GCS). The BMI was calculated. Mortality and the need for ICU admission were defined as primary outcomes, whereas secondary outcomes included cardiovascular complications and the need for mechanical ventilation. Thirty-eight patients presented with acute clozapine poisoning. The mean age of included patients was 25.2 ± 6. Patients were categorized regarding BMI into average weight (26.3%), overweight (31.6%), and obese (42.1%). Pearson's correlation indicated a significant positive correlation between BMI and respiratory rate (r = .364, p = .025). A significant negative correlation existed between BMI and GCS (r = .674, p ≤ .001). ROC curve reveals that BMI is an excellent predictor for the requirement of mechanical ventilation area under the curve (AUC > .9), a fair predictor of ICU admission AUC (.747). BMI had a sensitivity of 100% and specificity of 51.7 for the prediction of ICU admission. In conclusion, obesity increased the severity of toxicity and the incidence of poor clinical outcomes in patients with acute clozapine poisoning.

Impact of Obesity on Clinical Outcomes of Patients with Intra-Abdominal Hypertension and Abdominal Compartment Syndrome

Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are associated with high morbidity and mortality. Obesity may result in increased intra-abdominal pressure (IAP) and affect clinical outcomes of patients with IAH and/or ACS. This study aims to establish the impact of obesity on the clinical outcomes of IAH and ACS patients. A systematic search of Medline, Embase, and Scopus was performed in August 2022. Nine studies comprising 9938 patients were included. There were 65.1% males (n = 6250/9596). Patient demographics, comorbidities, and morbidities were analyzed in correlation with obesity and IAP. Obese patients had a higher risk of IAH (OR 8.5, p < 0.001). Obesity was associated with the need for renal replacement therapy, intensive care unit-acquired infections, systemic inflammatory response syndrome, acute respiratory distress syndrome, length of hospital stay, and mortality. This review highlights the lacunae in the existing literature to underpin the direct impact of obesity, independent of obesity-associated comorbidities, on the clinical outcomes of IAH and ACS.

The impact of body mass index on the prognostic performance of the Simplified Acute Physiology Score 3: A prospective cohort study

Objective

To assess the Simplified Acute Physiology Score 3 (SAPS3) prognostic score performance across different body mass index categories.

Methods

A retrospective cohort study in a general ICU in Brazil. A secondary analysis of medical records was performed with clinical and epidemiological data. Patients were stratified according to their body mass index (BMI) category, and a binary logistic regression was then performed to identify factors independently associated with mortality. SAPS3 accuracy was determined using the area under the receiver operating characteristics curve and the Hosmer-Lemeshow test. A modified Kaplan-Meyer plot was employed to evaluate death probability according to BMI. ICU mortality was evaluated as the primary outcome.

Results

A total of 2,179 patients (mean age of 67.9 years and female predominance (53.1%)) were enrolled. SAPS3 was found accurate in all groups except in the underweight (AUC: 0.694 95% CI 0.616–0.773; HL = 0.042). The patients in the underweight group tended to be older, have longer hospital stay, have worse functional status, and have a higher value on prognostic scores. After the adjustments, no statistically significant difference between the BMI groups was noted in relation to mortality, except for the low weight that presented a likelihood of death of 3.50 (95% CI, 1.43–8.58, p = 0.006).

Conclusion

This research showed that SAPS3 had poor accuracy in predicting ICU mortality in underweight patients. This group was shown to be an independent risk factor for worse clinical outcomes.

Understanding the Link Between Obesity and Severe COVID-19 Outcomes: Causal Mediation by Systemic Inflammatory Response

BACKGROUND

Obesity is an established risk factor for severe COVID-19 outcomes. The mechanistic underpinnings of this association are not well-understood.

OBJECTIVE

To evaluate the mediating role of systemic inflammation in obesity-associated COVID-19 outcomes.

METHODS

This hospital-based, observational study included 3828 SARS-CoV-2-infected patients who were hospitalized February to May 2020 at Massachusetts General Hospital (MGH) or Columbia University Irving Medical Center/New York Presbyterian Hospital (CUIMC/NYP). We use mediation analysis to evaluate whether peak inflammatory biomarkers (C-reactive protein [CRP], erythrocyte sedimentation rate [ESR], D-dimer, ferritin, white blood cell count and interleukin-6) are in the causal pathway between obesity (BMI ≥ 30) and mechanical ventilation or death within 28 days of presentation to care.

RESULTS

In the MGH cohort (n = 1202), obesity was associated with greater likelihood of ventilation or death (OR = 1.73; 95% CI = [1.25, 2.41]; P = 0.001) and higher peak CRP (P < 0.001) compared with nonobese patients. The estimated proportion of the association between obesity and ventilation or death mediated by CRP was 0.49 (P < 0.001). Evidence of mediation was more pronounced in patients < 65 years (proportion mediated = 0.52 [P < 0.001] vs 0.44 [P = 0.180]). Findings were more moderate but consistent for peak ESR. Mediation by other inflammatory markers was not supported. Results were replicated in CUIMC/NYP cohort (n = 2626).

CONCLUSION

Findings support systemic inflammatory pathways in obesity-associated severe COVID-19 disease, particularly in patients < 65 years, captured by CRP and ESR. Contextualized in clinical trial findings, these results reveal therapeutic opportunity to target systemic inflammatory pathways and monitor interventions in high-risk subgroups and particularly obese patients.

Obesity and Its Impact on Adverse In-Hospital Outcomes in Hospitalized Patients With COVID-19

BACKGROUND

An increasing level of evidence suggests that obesity not only is a major risk factor for cardiovascular diseases (CVDs) but also has adverse outcomes during COVID-19 infection.

METHODS

We used the German nationwide inpatient sample to analyze all hospitalized patients with confirmed COVID-19 diagnosis in Germany from January to December 2020 and stratified them for diagnosed obesity. Obesity was defined as body mass index ≥30 kg/m² according to the WHO. The impact of obesity on in-hospital case fatality and adverse in-hospital events comprising major adverse cardiovascular and cerebrovascular events (MACCE), acute respiratory distress syndrome (ARDS), venous thromboembolism (VTE), and others was analyzed.

RESULTS

We analyzed data of 176,137 hospitalizations of patients with confirmed COVID-19 infection; among them, 9,383 (5.3%) had an additional obesity diagnosis. Although COVID-19 patients without obesity were older (72.0 [interquartile range (IQR) 56.0/82.0] vs. 66.0 [54.0/76.0] years, p < 0.001), the CVD profile was less favorable in obese COVID-19 patients (Charlson comorbidity index 4.44 ± 3.01 vs. 4.08 ± 2.92, p < 0.001). Obesity was independently associated with increased in-hospital case fatality (OR 1.203 [95% CI 1.131-1.279], p < 0.001) and MACCE (OR 1.168 [95% CI 1.101-1.239], p < 0.001), ARDS (OR 2.605 [95% CI 2.449-2.772], p < 0.001), and VTE (OR 1.780 [95% CI 1.605-1.973], p < 0.001) and also associated with increased necessity of treatment on intensive care unit (OR 2.201 [95% CI 2.097-2.310], p < 0.001), mechanical ventilation (OR 2.277 [95% CI 2.140-2.422], p < 0.001), and extracorporeal membrane oxygenation (OR 3.485 [95% CI 3.023-4.017], p < 0.001).

CONCLUSIONS

Obesity independently affected case fatality, MACCE, ARDS development, VTE, and other adverse in-hospital events in patients with COVID-19 infection. Obesity should be taken into account regarding COVID-19 prevention strategies, risk stratification, and adequate healthcare planning. Maintaining a healthy weight is important not only to prevent cardiometabolic diseases but also for better individual outcomes during COVID-19 infection.

Excess Body Weight and Pancreatic Disease

Background

Excess body weight (EBW) is a risk factor for various acute and chronic conditions. Conversely, the "obesity paradox" suggests a protective effect of higher body weight on some disease outcomes. This article discusses the role of EBW along the disease continuum of pancreatitis and pancreatic cancer (PC) in terms of incidence and outcome.

Summary

Comparison of findings is hampered by the use of different methods to assess EBW. Nevertheless, in acute pancreatitis (AP) and PC, EBW, especially visceral obesity, presents a distinct risk factor and predictor of a negative outcome. Findings of a protective effect likely result from nonconsideration of fat distribution or other confounders. Regarding chronic pancreatitis (CP), few studies indicate lower incidence and a better outcome with higher body mass. However, there is insufficient evidence to confirm the existence of an obesity paradox. The precise mechanisms of how EBW affects the disease continuum require further elucidation but both common and disease-specific effects seem involved.

Key Messages

EBW is associated with higher incidence and a negative outcome in AP and PC. The association with CP is less conclusive. Thus, maintaining normal weight is advisable at any stage of the disease continuum.

Anthropometric analysis of body habitus and outcomes in critically ill COVID-19 patients

Aims

This study aimed to determine whether anthropometric markers of thoracic skeletal muscle and abdominal visceral fat tissue correlate with outcome parameters in critically ill COVID-19 patients.

Methods

We retrospectively analysed thoracic CT-scans of 67 patients in four ICUs at a university hospital. Thoracic skeletal muscle (total cross-sectional area (CSA); pectoralis muscle area (PMA)) and abdominal visceral fat tissue (VAT) were quantified using a semi-automated method. Point-biserial-correlation-coefficient, Spearman-correlation-coefficient, Wilcoxon rank-sum test and logistic regression were used to assess the correlation and test for differences between anthropometric parameters and death, ventilator- and ICU-free days and initial inflammatory laboratory values.

Results

Deceased patients had lower CSA and PMA values, but higher VAT values (p < 0.001). Male patients with higher CSA values had more ventilator-free days (p = 0.047) and ICU-free days (p = 0.017). Higher VAT/CSA and VAT/PMA values were associated with higher mortality (p < 0.001), but were negatively correlated with ICU length of stay in female patients only (p < 0.016). There was no association between anthropometric parameters and initial inflammatory biomarker levels. Logistic regression revealed no significant independent predictor for death.

Conclusion

Our study suggests that pathologic body composition assessed by planimetric measurements using thoracic CT-scans is associated with worse outcome in critically ill COVID-19 patients.

Impact of Body Mass Index on the Mortality of Critically Ill Patients Admitted to the Intensive Care Unit: An Observational Study

BACKGROUND

Obesity is a severe multifactorial disorder that carries high morbidity and mortality.

OBJECTIVES

This study aimed to evaluate the possible association between body mass index (BMI) and mortality in patients admitted to intensive care units (ICU).

METHODS

In this cross-sectional study, all patients admitted to the ICU were studied. The demographic characteristics, ICU, and hospital length of stay, organ failure, mortality, duration of mechanical ventilation, the occurrence of nosocomial infection, and type of admission were recorded for all patients. Patients were categorized based on their BMI.

RESULTS

In total, 502 patients were studied who 53.2% of them were male. Most of the death (28.6%) were recorded in the obesity class II patients, while the lowest rate (3.9%) was for the normal-weight patients (P value < 0.001). The APACHE II and waist circumference had a statistically significant association with the mortality rate (P value < 0.001). After adjusting for age and gender, a significant association was found between waist circumference and mortality rate (OR = 1.15, 95% CI = 1.03 - 1.29; P value = 0.014), APACHE II score, and mortality rate (OR = 2.79, 95% CI = 1.91 - 4.07, P value < 0.001); but there was no significant association between BMI and mortality rate.

CONCLUSIONS

This study demonstrated that BMI is associated with an increased risk of mortality, regardless of age and gender. However, after adjusting for age and gender as confounding factors, BMI didn't have a significant effect on mortality, while the APACHE II score and waist circumference affected the mortality rate.

Analyses of abdominal adiposity and metabolic syndrome as risk factors for respiratory distress in COVID-19

BACKGROUND

Several characteristics of the metabolic syndrome, such as obesity and hypertension, have emerged as risk factors for a poor clinical outcome in COVID-19. However, most reports lack data on the metabolic syndrome itself. This study investigated prospectively the relationship between respiratory deterioration and the presence of metabolic syndrome or abdominal adiposity in patients with COVID-19.

METHODS

A prospective observational cohort study analysing patients with respiratory symptoms who presented at a local emergency department in the Netherlands. The influence of abdominal adiposity-assessed by an increased waist-hip ratio-and metabolic syndrome on respiratory deterioration and the length of hospital stay were analysed with multivariable logistic regressions and Kaplan-Meier analyses.

RESULTS

In total, 166 patients were analysed, of whom 86 (52%) tested positive for COVID-19. The prevalence of metabolic syndrome did not differ between patients with COVID-19 with and without the need for intubation or level of supportive care (37.5% vs 48.4%, p=0.338). In contrast, abdominal adiposity is an independent risk factor for respiratory distress in COVID-19, adjusted for metabolic syndrome, age, gender and BMI (OR 1.11, 95% CI 1.02 to 1.20, p=0.014).

CONCLUSION

This study shows that abdominal adiposity, and not the presence of metabolic syndrome, is associated with clinical deterioration in COVID-19. This prospective study provides further insight into the risk stratification of patients with COVID-19 based on a simple measurement as the waist and hip circumference.

TRIAL REGISTRATION NUMBER

NL8580.

ICU admission body composition: skeletal muscle, bone, and fat effects on mortality and disability at hospital discharge-a prospective, cohort study

Background

Reduced body weight at the time of intensive care unit (ICU) admission is associated with worse survival, and a paradoxical benefit of obesity has been suggested in critical illness. However, no research has addressed the survival effects of disaggregated body constituents of dry weight such as skeletal muscle, fat, and bone density.

Methods

Single-center, prospective observational cohort study of medical ICU (MICU) patients from an academic institution in the USA. Five hundred and seven patients requiring CT scanning of chest or abdomen within the first 24 h of ICU admission were evaluated with erector spinae muscle (ESM) and subcutaneous adipose tissue (SAT) areas and with bone density determinations at the time of ICU admission, which were correlated with clinical outcomes accounting for potential confounders.

Results

Larger admission ESM area was associated with decreased odds of 6-month mortality (OR per cm², 0.96; 95% CI, 0.94–0.97; p < 0.001) and disability at discharge (OR per cm², 0.98; 95% CI, 0.96–0.99; p = 0.012). Higher bone density was similarly associated with lower odds of mortality (OR per 100 HU, 0.69; 95% CI, 0.49–0.96; p = 0.027) and disability at discharge (OR per 100 HU, 0.52; 95% CI, 0.37–0.74; p < 0.001). SAT area was not significantly associated with these outcomes’ measures. Multivariable modeling indicated that ESM area remained significantly associated with 6-month mortality and survival after adjusting for other covariates including preadmission comorbidities, albumin, functional independence before admission, severity scores, age, and exercise capacity.

Conclusion

In our cohort, ICU admission skeletal muscle mass measured with ESM area and bone density were associated with survival and disability at discharge, although muscle area was the only component that remained significantly associated with survival after multivariable adjustments. SAT had no association with the analyzed outcome measures.

What factors predict length of stay in the intensive care unit? Systematic review and meta-analysis

PURPOSE

Studies have shown that a small percentage of ICU patients have prolonged length of stay (LoS) and account for a large proportion of resource use. Therefore, the identification of prolonged stay patients can improve unit efficiency. In this study, we performed a systematic review and meta-analysis to understand the risk factors of ICU LoS.

MATERIALS AND METHODS

We searched MEDLINE, Embase and Scopus databases from inception to November 2018. The searching process focused on papers presenting risk factors of ICU LoS. A meta-analysis was performed for studies reporting appropriate statistics.

RESULTS

From 6906 citations, 113 met the eligibility criteria and were reviewed. A meta-analysis was performed for six factors from 28 papers and concluded that patients with mechanical ventilation, hypomagnesemia, delirium, and malnutrition tend to have longer stay, and that age and gender were not significant factors.

CONCLUSIONS

This work suggested a list of risk factors that should be considered in prediction models for ICU LoS, as follows: severity scores, mechanical ventilation, hypomagnesemia, delirium, malnutrition, infection, trauma, red blood cells, and PaO2:FiO2. Our findings can be used by prediction models to improve their predictive capacity of prolonged stay patients, assisting in resource allocation, quality improvement actions, and benchmarking analysis.

Associations between Central Obesity and Outcomes of Adult In-hospital Cardiac Arrest: A Retrospective Cohort Study

To investigate the association between central obesity and outcomes following in-hospital cardiac arrest (IHCA). A single-centred retrospective study was conducted. Adult patients that experienced IHCA during 2006-2015 were screened. Body mass index (BMI) was calculated at hospital admission. Central obesity-related anthropometric parameters were measured by analysing computed tomography images. A total of 648 patients were included, with mean BMI of 23.0 kg/m2. The proportions of BMI-defined obesity in this cohort were underweight (13.1%), normal weight (41.4%), overweight (31.5%) and obesity (14.0%). The mean waist circumference was 85.9 cm with mean waist-to-height ratio (WHtR) of 0.53. The mean sagittal abdominal diameter was 21.2 cm with mean anterior and posterior abdominal subcutaneous adipose tissue (SAT) depths of 1.6 and 2.0 cm, respectively. Multivariate logistic regression analyses indicated BMI of 11.7-23.3 kg/m2 (odds ratio [OR]: 2.53, 95% confidence interval [CI]: 1.10-5.85; p-value = 0.03), WHtR of 0.49-0.59 (OR: 3.45, 95% CI: 1.56-7.65; p-value = 0.002) and anterior abdominal SAT depth <1.9 cm (OR: 2.84, 95% CI: 1.05-7.74; p-value = 0.04) were positively associated with the favourable neurological outcome. Central obesity was associated with poor IHCA outcomes, after adjusting for the effects of BMI.

Impact of pathologic body composition assessed by CT-based anthropometric measurements in adult patients with multiple trauma: a retrospective analysis

PURPOSE

In recent years, there has been mounting evidence on the clinical importance of body composition, particularly obesity and sarcopenia, in various patient populations. However, the relevance of these pathologic conditions remains controversial, especially in the field of traumatology. Computed tomography-based measurements allow clinicians to gain a prompt and thorough assessment of fat and muscle compartments in trauma patients. Our aim was to investigate whether CT-based anthropometric parameters of fat and muscle tissues show correlations with key elements of pre-hospital and clinical care in an adult population with multiple trauma.

METHODS

In this retrospective analysis we searched our institutional records of the German Trauma Registry (TraumaRegister DGU^®) from January 2008 to May 2014. Included were 297 adult trauma patients with multiple trauma who underwent a whole-body CT-scan on admission and were treated in an ICU. We measured anthropometric determinants of abdominal core muscle and adipose tissue using the digital imaging software OsiriX™. Multivariate linear and logistic regression analyses were conducted to unveil potential correlations.

RESULTS

None of the obesity-linked anthropometric parameters were associated with longer pre-hospital or initial ED treatment times. Obese patients were less frequently intubated at the site of the accident. Patients with increased abdominal fat tissue received on average lower volumes during fluid resuscitation in the pre-hospital phase but were not more often in shock on admission. During ED treatment, fluid resuscitation and transfusion volumes were not affected by abdominal fat tissue, although transfusion rates were higher in the obese. Furthermore, damage control surgeries took place less frequently in patients with increased abdominal fat tissue markers. Obesity parameters did not affect the prevalence of sepsis, although increased abdominal fat was associated with higher white blood cell counts on admission. Finally, there was no statistically significant correlation between sarcopenia or obesity markers and duration of mechanical ventilation, ICU length of stay or neurologic outcome.

CONCLUSION

CT-based assessment of abdominal fat and muscle mass is a simple method in revealing pathologic body composition in trauma patients. Our study suggests that obesity influences pre-hospital and ED treatment and early immune response in multiple trauma. Nevertheless, we could not demonstrate any significant effect of abdominal fat and muscle tissue parameters on the course of treatment, in particular the duration of mechanical ventilation, ICU length of stay and neurologic outcome.

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

During critical illness, obese patients have better outcomes compared to patients with normal BMI, and this is known as the obesity paradox. The difference in comorbidity burden have been implied to be responsible for the paradox. We performed a retrospective review from 2001 to 2012 of critically ill patients from the Medical Information Mart for Intensive Care database. We included 11,433 patients and classified them according to body mass index (BMI) and comorbidity burden (Elixhauser comorbidity measure). The odds of inpatient mortality were lower in obese patients compared to patients with normal BMI; in group with the least comorbidity score (Elixhauser <0) [OR: 0.47, CI (0.28-0.80), p-value 0.006] and higher comorbidity scores, (Elixhauser 1-5) [(OR: 0.66, CI (0.46-0.95), p-value 0.02)] and (Elixhauser 6-13) [OR: 0.69, CI (0.53-0.92), p-value 0.01]. 30-day mortality was also significantly lower in obese patients, in groups with the lowest (Elixhauser <0) [OR:49, CI (0.31-0.77), p-value 0.002] as well as the highest comorbidity burden (Elixhauser >14) [OR:0.59, CI (0.45-0.77), p-value <.001]. Subgroup analysis in patients with various comorbidities showed better outcomes in obese patients. These findings show that the decreased odds of mortality in critically ill obese patients is independent of the comorbidity burden or type of comorbidity.

High Visceral Adipose Tissue to Subcutaneous Adipose Tissue Ratio as a Predictor of Mortality in Acute Respiratory Distress Syndrome

BACKGROUND

We aimed to further determine the relationship between the areas of visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and the ratio of VAT to SAT (VAT/SAT) with the outcomes of acute respiratory distress syndrome (ARDS) patients.

METHODS

A retrospective study was performed on patients with ARDS in 7 intensive care units (ICU) of West China Hospital, Sichuan University.

RESULTS

A total of 169 patients were included in the analysis. Abdominal computed tomography scans of each patient within 24 hours of being admitted to the ICU were assessed by at least 2 investigators. Higher VAT/SAT was related with higher hospital mortality (22% vs. 44%, P = 0.003; adjusted odds ratio [aOR] 0.699, 95% CI 0.530-0.922 ([P = 0.011]). On the contrary, higher SAT and VAT were related to lower hospital mortality in ARDS (aOR 1.077, 95% CI 1.037-1.119 [P < 0.001]; aOR 1.017, 95% CI 1.004-1.030 [P = 0.011], respectively). Patients with higher SAT and VAT had shorter length of ICU stay (ICU LOS) (26.26 vs. 15.83 days, P = 0.031; 25.16 vs. 14.19 days, P = 0.007, respectively), while VAT/SAT was not related with ICU LOS. Moreover, we did not find any significant relationship either between VAT/SAT and mechanical ventilation-free days or between SAT and mechanical ventilation-free days.

CONCLUSIONS

This study suggests that VAT/SAT can contribute to adverse outcomes of patients with ARDS. However, higher SAT and VAT were related to better prognosis of ARDS patients.

ICU Admission Muscle and Fat Mass, Survival, and Disability at Discharge: A Prospective Cohort Study

BACKGROUND

Skeletal muscle dysfunction occurring as a result of ICU admission associates with higher mortality. Although preadmission higher BMI correlates with better outcomes, the impact of baseline muscle and fat mass has not been defined. We therefore investigated the association of skeletal muscle and fat mass at ICU admission with survival and disability at hospital discharge.

METHODS

This single-center, prospective, observational cohort study included medical ICU (MICU) patients from an academic institution in the Unites States. A total of 401 patients were evaluated with pectoralis muscle area (PMA) and subcutaneous adipose tissue (SAT) determinations conducted by CT scanning at the time of ICU admission, which were later correlated with clinical outcomes accounting for potential confounders.

RESULTS

Larger admission PMA was associated with better outcomes, including higher 6-month survival (OR, 1.03; 95% CI, 1.01-1.04; P < .001), lower hospital mortality (OR, 0.96; 95% CI, 0.93-0.98; P < .001), and more ICU-free days (slope, 0.044 ± 0.019; P = .021). SAT was not significantly associated with any of the measured outcomes. In multivariable analyses, PMA association persisted with 6 months and hospital survival and ICU-free days, whereas SAT remained unassociated with survival or other outcomes. PMA was not associated with regaining of independence at the time of hospital discharge (OR, 0.99; 95% CI, 0.98-1.01; P = .56).

CONCLUSIONS

In this study cohort, ICU admission PMA was associated with survival during and following critical illness; it was unable to predict regaining an independent lifestyle following discharge. ICU admission SAT mass was not associated with survival or other measured outcomes.

Higher BMI is associated with reduced mortality but longer hospital stays following ICU discharge in critically ill Asian patients

BACKGROUND & AIMS

Asians with similar body mass index (BMI) as the Caucasians are at higher health risk as compared to their counterparts. Although the mean weight of patients admitted to the intensive care unit (ICU) is increasing but the relation between BMI with 28-day mortality and length of stay (LOS) following ICU discharge in Asian patients is not well studied.

METHODS

We included all adult patients admitted to the ICU of a tertiary hospital who received mechanical ventilation (MV) for at least 48 hours between October 2013 and September 2014. Demographics, BMI, MV, comorbidities, ICU scores (Acute Physiology And Chronic Health Evaluation (APACHE) II and sequential organ failure assessment (SOFA)), use of vasopressor, renal replacement therapy and calorie supplementation were collected from the ICU database. BMI was categorized into four groups according to the World Health Organization's Asian BMI recommendation. Post-ICU LOS (days) was calculated from ICU discharge to hospital discharge in hospital survivors. We used multivariable logistic regression to identify factors associated with 28-day mortality and post-ICU LOS of more than 7 days.

RESULTS

In a cohort of 273 patients (male 62%, mean age 58.4 ± 17 years), the prevalence of overweight/obesity was 53%. In the bivariate analysis, 28-day mortality was lower (p = 0.014) and post-ICU LOS longer (p = 0.01) in the overweight/obese groups. In the multivariable logistic regression analysis, APACHE II (Odds ratio, OR 1.10, CI 1.05-1.16), SOFA (OR 1.17, CI 1.05-1.31), duration of MV (days, OR 1.14, CI 1.05-1.25) were associated with increased and higher BMI groups (p < 0.001) with decreased 28-day mortality. Further analysis of 196 hospital survivors showed age (OR 1.04, CI 1.02-1.06), duration of MV (days, OR 1.14, CI 1.02-1.27) and higher Asian BMI (p = 0.042) were associated with longer post-ICU LOS. The odds of longer post-ICU LOS amongst overweight and obese patients were 1.27 (CI 0.59-2.73) and 1.62 (CI 0.69-3.81) times that of those with normal BMI respectively.

CONCLUSION

In multiethnic critically ill Asian patients, the prevalence of overweight/obesity was high. Although higher BMI was associated with reduced risk of 28-day mortality, obese patients stayed significantly longer in the hospital following ICU discharge.

Association between Modified Body Mass Index and 30-Day and 1-Year Mortality after Intensive Care Unit Admission: A Retrospective Cohort Study

Because conventional body mass index (cBMI) does not reflect fluid accumulation, modified BMI (mBMI, serum albumin multiplied by cBMI) is a more accurate measure of malnutrition status. This study aimed to determine whether mortality after intensive care unit (ICU) admission was associated with cBMI, mBMI, and/or serum albumin levels. The medical records of patients who were admitted to a tertiary hospital ICU between 1 January 2012 and 31 July 2016 were retrospectively reviewed. In total, 6169 ICU-admitted patients were included in the analyses. Multivariate Cox regression analyses revealed that low cBMI, mBMI and albumin level were significantly associated with 30-day and 1-year mortality after ICU admission (hazard ratio < 1.0, p < 0.05). The adjusted area under the curve (AUC) of mBMI for 1-year mortality was significantly higher than that of cBMI (p < 0.001), but not significantly different from that of albumin level (p = 0.098). Low values of mBMI, cBMI and albumin were independently associated with 30-day and 1-year mortality after ICU admission. Combining cBMI and albumin (mBMI) did not increase the validity of the AUC of albumin for 1-year mortality after ICU admission. Our study showed that serum albumin alone, rather than mBMI (combining cBMI), is recommended in predicting mortality among ICU patients.

[Extreme obesity-particular aspect of invasive and noninvasive ventilation]

The obesity rate is increasing worldwide and the percentage of obese patients in the intensive care unit (ICU) is rising concomitantly. Ventilatory support strategies in obese patients must take into account the altered pathophysiological conditions. Unfortunately, prospective randomized multicenter trials on this subject are lacking. Therefore, current strategies are based on the individual experiences of ICU physicians and single-center studies. Noninvasive ventilation (NIV) in critically ill patients with acute respiratory failure and obesity hypoventilation syndrome (OHS) is an efficient treatment option and should be provided as early as possible is an effort to avoid intubation. Patient positioning is also crucial: half-sitting positions (>45°) improve lung compliance and functional residual capacity in patients with respiratory failure. Transpulmonary pressure measurements or the Acute Respiratory Distress Syndrome (ARDS) Network tables may help to adjust the optimal positive end-expiratory pressure (PEEP). The tidal volume should be adapted to the ideal and not the actual bodyweight (V_t = 6 ml/kg of ideal bodyweight) to avoid lung damage and (additional) right ventricular stress. Under particular conditions, inspiratory pressures >30 cmH₂O may be tolerated for a limited duration. Early tracheostomy combined with termination/reduction of sedation and relaxation is controversy discussed in the literature as a therapeutic option during invasive ventilation of morbidly obese patients. However, data on early tracheotomy in obese respiratory failure patients are rare and this should be regarded as an individual treatment attempt only. In cases of refractory lung failure, venovenous extracorporeal membrane oxygenation (vv-ECMO) is an option despite anatomic changes in morbid obesity.

The Obesity Paradox Is Not Observed in Critically Ill Patients on Early Enteral Nutrition

OBJECTIVES

To investigate the association between body mass index and mortality in a large, ICU population and determine if the relationship is observed among a subgroup of patients ordered early enteral nutrition.

DESIGN

Retrospective cohort study within a national clinical mixed ICU database of patients admitted between January 1, 2008, and June 30, 2015.

SETTING

Initial ICU admissions among patients monitored by tele-ICU programs and recorded in the Philips eICU Research Institute database.

PATIENTS

A total of 1,042,710 adult patient stays with ICU length of stay more than 24 hours, of which 74,771 were ordered enteral nutrition within the first 48 hours.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Patient stays from 409 ICUs were included. The average age, Acute Physiology and Chronic Health Evaluation IV score, and hospital mortality were 63.6 years, 56.7, and 9.0%, respectively. Hospital mortality among body mass index categories was estimated by multivariable modified Poisson regression models. Compared with the body mass index category 25.0-29.9 kg/m, hospital mortality was higher among underweight (body mass index, < 18.5; relative risk, 1.35; 95% CI, 1.32-1.39), normal weight (body mass index, 18.5-24.9; relative risk, 1.10; 95% CI, 1.09-1.12), and the extremely obese (body mass index, ≥ 50.0; relative risk, 1.10; 95% CI, 1.05-1.15). However, the risk was not statistically different from patients with body mass index 30.0-49.9 kg/m. Among patients ordered early enteral nutrition, the risk of mortality in the body mass index category 25.0-29.9 kg/m was not statistically different from those in the normal weight or extremely obese groups.

CONCLUSIONS

A survival advantage for overweight and obese patients was observed in this large cohort of critically ill patients. However, among those ordered early enteral nutrition, the survival disadvantage for body mass index categories less than 25.0 kg/m was minimal or unobservable when compared with higher body mass index categories.

[Above and beyond BMI : Alternative methods of measuring body fat and muscle mass in critically ill patients and their clinical significance]

Obesity leads to better survival in critically ill patients. Although there are several studies confirming this thesis, the "obesity paradox" is still surprising from the clinician's perspective. One explanation for the "obesity paradox" is the fact that the body mass index (BMI), which is used in almost all clinical evaluations to determine weight categories, is not an appropriate measure of fat and skeletal muscle mass and its distribution in critically ill patients. In addition, height and weight are frequently estimated rather than measured. Central obesity has been identified in many disorders as an independent risk factor for an unfavourable outcome. The first clues are to be found in intensive care. Along with obesity, an individual's entire muscle mass is a variable that has an influence on outcome. Central obesity can be measured relatively easily with an abdominal calliper, but the calculation of muscle mass is more complex. A valid and detailed measurement of this can be obtained using computed tomography (CT) images, acquired during routine care. For future clinical observation or interventional studies, single cross-sectional CT is a more sophisticated tool for measuring patients' anthropometry than a measuring tape and callipers. Patients with sarcopenic obesity, for example, who may be at a particular risk, can only be identified using imaging procedures such as single cross-sectional CT. Thus, BMI should take a back seat as an anthropometric tool, both in the clinic and in research.

The Critical Care Obesity Paradox and Implications for Nutrition Support

Obesity is a leading cause of preventable death worldwide. The prevalence of obesity has been increasing and is associated with an increased risk for other co-morbidities. In the critical care setting, nearly one third of patients are obese. Obese critically ill patients pose significant physical and on-physical challenges to providers, including optimization of nutrition therapy. Intuitively, obese patients would have worse critical care-related outcome. On the contrary, emerging data suggests that critically ill obese patients have improved outcomes, and this phenomenon has been coined "the obesity paradox." The purposes of this review will be to outline the historical views and pathophysiology of obesity and epidemiology of obesity, describe the challenges associated with obesity in the intensive care unit setting, review critical care outcomes in the obese, define the obesity-critical care paradox, and identify the challenges and role of nutrition support in the critically ill obese patient.

Obesity in the intensive care unit: risks and complications

The steady growing prevalence of critically ill obese patients is posing diagnostic and management challenges across medical and surgical intensive care units. The impact of obesity in the critically ill patients may vary by type of critical illness, obesity severity (obesity distribution) and obesity-associated co-morbidities. Based on pathophysiological changes associated with obesity, predominately in pulmonary reserve and cardiac function, critically ill obese patients may be at higher risk for acute cardiovascular, pulmonary and renal complications in comparison to non-obese patients. Obesity also represents a dilemma in the management of other critical care areas such as invasive mechanical ventilation, mechanical ventilation liberation, hemodynamic monitoring and pharmacokinetics dose adjustments. However, despite higher morbidity associated with obesity in the intensive care unit (ICU), a paradoxical lower ICU mortality ("obesity paradox") is demonstrated in comparison to non-obese ICU patients. This review article will focus on the unique pathophysiology, challenges in management, and outcomes associated with obesity in the ICU.

Being Overweight Is Associated With Greater Survival in ICU Patients: Results From the Intensive Care Over Nations Audit

OBJECTIVE

To assess the effect of body mass index on ICU outcome and on the development of ICU-acquired infection.

DESIGN

A substudy of the Intensive Care Over Nations audit.

SETTING

Seven hundred thirty ICUs in 84 countries.

PATIENTS

All adult ICU patients admitted between May 8 and 18, 2012, except those admitted for less than 24 hours for routine postoperative monitoring (n = 10,069). In this subanalysis, only patients with complete data on height and weight (measured or estimated) on ICU admission in order to calculate the body mass index were included (n = 8,829).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Underweight was defined as body mass index less than 18.5 kg/m, normal weight as body mass index 18.5-24.9 kg/m, overweight as body mass index 25-29.9 kg/m, obese as body mass index 30-39.9 kg/m, and morbidly obese as body mass index greater than or equal to 40 kg/m. The mean body mass index was 26.4 ± 6.5 kg/m. The ICU length of stay was similar among categories, but overweight and obese patients had longer hospital lengths of stay than patients with normal body mass index (10 [interquartile range, 5-21] and 11 [5-21] vs 9 [4-19] d; p < 0.01 pairwise). ICU mortality was lower in morbidly obese than in normal body mass index patients (11.2% vs 16.6%; p = 0.015). In-hospital mortality was lower in morbidly obese and overweight patients and higher in underweight patients than in those with normal body mass index. In a multilevel Cox proportional hazard analysis, underweight was independently associated with a higher hazard of 60-day in-hospital death (hazard ratio, 1.32; 95% CI, 1.05-1.65; p = 0.018), whereas overweight was associated with a lower hazard (hazard ratio, 0.79; 95% CI, 0.71-0.89; p < 0.001). No body mass index category was associated with an increased hazard of ICU-acquired infection.

CONCLUSIONS

In this large cohort of critically ill patients, underweight was independently associated with a higher hazard of 60-day in-hospital death and overweight with a lower hazard. None of the body mass index categories as independently associated with an increased hazard of infection during the ICU stay.

Physiological and management implications of obesity in critical illness

Obesity is highly prevalent in the United States and is becoming increasingly common worldwide. The anatomic and physiological changes that occur in obese individuals may have an impact across the spectrum of critical illness. Obese patients may be more susceptible to hypoxemia and hypercapnia. During mechanical ventilation, elevated end-expiratory pressures may be required to improve lung compliance and to prevent ventilation-perfusion mismatch due to distal airway collapse. Several studies have shown an increased risk of organ dysfunction such as the acute respiratory distress syndrome and acute kidney injury in obese patients. Predisposition to ventricular hypertrophy and increases in blood volume should be considered in fluid management decisions. Obese patients have accelerated muscle losses in critical illness, making nutrition essential, although the optimal predictive equation to estimate nutritional needs or formulation for obese patients is not well established. Many common intensive care unit medications are not well studied in obese patients, necessitating understanding of pharmacokinetic concepts and consultation with pharmacists. Obesity is associated with higher risk of deep venous thrombosis and catheter-associated bloodstream infections, likely related to greater average catheter dwell times. Logistical issues such as blood pressure cuff sizing, ultrasound assistance for procedures, diminished quality of some imaging modalities, and capabilities of hospital equipment such as beds and lifts are important considerations. Despite the physiological alterations and logistical challenges involved, it is not clear whether obesity has an effect on mortality or long-term outcomes from critical illness. Effects may vary by type of critical illness, obesity severity, and obesity-associated comorbidities.

The association between obesity and outcomes in critically ill patients

BACKGROUND

Obesity rates are increasing worldwide, particularly in North America. The impact of obesity on the outcome of critically ill patients is unclear.

METHODS

A prospective observational cohort study of consecutive patients admitted to a tertiary critical care unit in Canada between January 10, 2008 and March 31, 2009 was conducted. Exclusion criteria were age <18 years, admission <24 h, planned cardiac surgery, pregnancy, significant ascites, unclosed surgical abdomen and brain death on admission. Height, weight and abdominal circumference were measured at the time of intensive care unit (ICU) admission. Coprimary end points were ICU mortality and a composite of ICU mortality, reintubation, ventilator-associated pneumonia, line sepsis and ICU readmission. Subjects were stratified as obese or nonobese, using two separate metrics: body mass index (BMI) ≥ 30 kg/m(2) and a novel measurement of 75th percentile for waist-to-height ratio (WHR).

RESULTS

Among 449 subjects with a BMI ≥ 18.5 kg/m(2), both BMI and WHR were available for comparative analysis in 348 (77.5%). Neither measure of obesity was associated with the primary end points. BMI ≥ 3 0 kg/m(2) was associated with a lower odds of six-month mortality than the BMI <30 kg/m(2) group (adjusted OR 0.59 [95% CI 0.36 to 0.97]; P=0.04) but longer intubation times (adjusted RR 1.56 [95% CI 1.17 to 2.07]; P=0.003) and longer ICU length of stay (adjusted RR 1.67 [95% CI 1.21 to 2.31]; P=0.002). Conversely, measurement of 75th percentile for WHR was associated only with decreased ICU readmission (OR 0.23 [95% CI 0.07 to 0.79]; P=0.02).

CONCLUSIONS

Obesity was not necessarily associated with worse outcomes in critically ill patients.

Is the negative relationship between obesity and bone mineral content greater for older women?

Obesity and osteoporosis are two important body composition problems with increasing prevalences in aged populations. Traditionally, obesity has been regarded as being beneficial to bone health. However, the protective effect of obesity on osteoporosis has been questioned. In some recent studies, obesity, as defined by percentage body fat, was regarded as a risk factor for osteoporosis. The purpose of this study was to (1) evaluate the effect of waist circumference, a surrogate measure for abdominal obesity, on bone mineral content (BMC) and (2) examine whether the effect of waist circumference increases with advancing age. The study population is made up of women aged over 45 years who completed the body composition and bone mineral density examinations in the fifth Korea National Health and Nutrition Examination Survey in 2010. Subjects who take estrogen or are under medical treatment for osteoporosis were excluded. Stroke patients are also excluded. Femoral neck, total-hip, and whole-body BMC were measured by dual-energy X-ray absorptiometry. A total of 1,434 subjects were included in the analysis. Waist circumference was negatively associated with BMC in all tested regions after correction for weight, menopausal status, smoking, drinking, and exercise. In addition, the negative association between waist circumference and BMC in the femoral neck and total hip increases with age, after correction for confounding factors, showing an interaction effect between waist circumference and age on BMC. In conclusion, this study shows that the negative relationship between waist circumference and BMC in the femoral neck and total hip is greater for older women.

Unraveling the clonal hierarchy of somatic genomic aberrations

Defining the chronology of molecular alterations may identify milestones in carcinogenesis. To unravel the temporal evolution of aberrations from clinical tumors, we developed CLONET, which upon estimation of tumor admixture and ploidy infers the clonal hierarchy of genomic aberrations. Comparative analysis across 100 sequenced genomes from prostate, melanoma, and lung cancers established diverse evolutionary hierarchies, demonstrating the early disruption of tumor-specific pathways. The analyses highlight the diversity of clonal evolution within and across tumor types that might be informative for risk stratification and patient selection for targeted therapies. CLONET addresses heterogeneous clinical samples seen in the setting of precision medicine.

Influence of abdominal obesity on multiorgan dysfunction and mortality in acute respiratory distress syndrome patients treated with prone positioning

PURPOSE

Obesity is a worldwide pandemic, and obese patients face an increased risk of developing acute respiratory distress syndrome (ARDS). Prone positioning (PP) is a frequently used intervention in the treatment of ARDS. There are no data describing the impact of PP on morbidity and mortality in abdominally obese patients. We report our observations in abdominally obese ARDS patients treated with PP.

MATERIALS AND METHODS

Patients with ARDS (n=82) were retrospectively divided into 2 groups characterized by presence (n=41) or absence (n=41) of abdominal obesity as defined by a sagittal abdominal diameter of 26 cm or more.

RESULTS

There was no difference in cumulative time abdominally obese patients were placed in prone position from admission to day 7 (41.0 hours [interquartile range, 50.5 hours] vs 39.5 hours [interquartile range, 61.5 hours]; P=.65) or in overall intensive care unit mortality (34% vs 34%; P=1). However, abdominally obese patients developed renal failure (83% vs 35%; P<.001) and hypoxic hepatitis (22% vs 2%; P=.015) more frequently. A significant interaction effect between abdominal obesity and prone position with respect to mortality risk (likelihood ratio, P=.0004) was seen if abdominally obese patients were treated with prolonged cumulative PP.

CONCLUSION

A cautious approach to PP should be considered in abdominally obese patients.

Obesity and risk of sepsis: a population-based cohort study

OBJECTIVE

Sepsis, the syndrome of microbial infection complicated by systemic inflammation, is associated with significant morbidity and mortality. To determine if obesity increases risk of sepsis events.

DESIGN AND METHODS

Data from the 30,239 subject population-based longitudinal cohort study REasons for Geographic and Racial Differences in Stroke (REGARDS) were used. Using measurements at the start of the study, we defined obesity using body mass index (BMI; <18.5 kg/m(2) = underweight, 18.5-24.9 = normal, 25.0-29.9 = overweight, 30.0-39.9 = obese, ≥40 = morbidly obese) and waist circumference (WC; [male ≤102 cm or female ≤88 cm] = normal, [male >102 cm or female >88 cm] = obese). Over an 8-year observation period, we evaluated the association between obesity and subsequent sepsis events, adjusting for sociodemographic factors, health behaviors, chronic medical conditions, statin use, and high-sensitivity C-reactive protein.

RESULTS

There were 975 incident sepsis events. Compared to those with a BMI of 18.5-24.9, sepsis risk was higher only for BMI ≥ 40 (hazard ratio [HR] 1.57, [1.16-2.14]). Risk of sepsis was associated with increased WC (HR 1.34 [1.14-1.56]). In a model with both BMI and WC, sepsis risk was associated with increased WC (HR 1.47 [1.20-1.79]) but not BMI.

CONCLUSIONS

Obesity is independently associated with future sepsis events. WC is a better predictor of future sepsis risk than BMI.

Outcomes of morbidly obese patients receiving invasive mechanical ventilation: a nationwide analysis

BACKGROUND

Critically ill, morbidly obese patients (BMI≥40 kg/m2) are at high risk of respiratory failure requiring invasive mechanical ventilation (IMV). It is not clear if outcomes of critically ill, obese patients are affected by obesity. Due to limited cardiopulmonary reserve, they may have poor outcomes. However, literature to this effect is limited and conflicted.

METHODS

We used the Nationwide Inpatient Sample from 2004 to 2008 to examine the outcomes of morbidly obese people receiving IMV and compared them to nonobese people. We identified hospitalizations requiring IMV and morbid obesity using International Classification of Diseases, 9th Revision, Clinical Modification codes. Primary outcomes studied were inhospital mortality, rates of prolonged mechanical ventilation (≥96 h), and tracheostomy. Multivariable logistic regression was used to adjust for potential confounding variables. We also examined outcomes stratified by number of organs failing.

RESULTS

Of all hospitalized, morbidly obese people, 2.9% underwent IMV. Mean age, comorbidity score, and severity of illness were lower in morbidly obese people. The adjusted mortality was not significantly different in morbidly obese people (OR 0.89; 95% CI, 0.74-1.06). When stratified by severity of disease, there was a stepwise increase in risk for mortality among morbidly obese people relative to nonobese people (range: OR, 0.77; 95% CI, 0.58-1.01 for only respiratory failure, to OR, 4.14; 95% CI, 1.11-15.3 for four or more organs failing). Rates of prolonged mechanical ventilation were similar, but rate of tracheostomy (OR 2.19; 95% CI, 1.77-2.69) was significantly higher in patients who were morbidly obese.

CONCLUSIONS

Morbidly obese people undergoing IMV have a similar risk for death as nonobese people if only respiratory failure is present. When more organs fail, morbidly obese people have increased risk for mortality compared with nonobese people.

Sagittal abdominal diameter may effectively predict future complications and increased mortality in intensive care unit patients with severe sepsis

PURPOSE

To investigate whether increased visceral adipose tissue is a risk factor for increased morbidity and mortality in intensive care patients with severe sepsis.

MATERIALS AND METHODS

In this prospective cohort study, body mass index (BMI) and sagittal abdominal diameter (SAD) were measured in all patients with severe sepsis immediately after admission in the intensive care unit (ICU). The patients were followed up until death or discharge from ICU. The study's primary outcome measure was mortality until day 60 after admission, while secondary outcomes were morbidity, length of stay, and length of ventilation in ICU.

RESULTS

Of the 30 patients, 24 (80%) developed septic shock, 6 (20%) multiple organ dysfunction syndrome, 13 (43.3%) necessitated continuous venovenous hemodiafiltration, while 6 (20%) of them died. BMI and SAD had a statistically significant positive linear correlation with ICU length of stay (P < .001) and length of ventilation (P ≤ .001). However, only SAD was significantly correlated with the development of multiple organ dysfunction syndrome (P = .033), the need for continuous venovenous hemodiafiltration (P = .004), and death (P = .033).

CONCLUSION

An increased SAD may effectively predict future complications and increased mortality in intensive care unit patients with severe sepsis.

Life Years Lost Associated with Obesity-Related Diseases for U.S. Non-Smoking Adults

The objectives of this paper are to predict life years lost associated with obesity-related diseases (ORDs) for U.S. non-smoking adults, and to examine the relationship between those ORDs and mortality. Data from the National Health Interview Survey, 1997-2000, were used. We employed mixed proportional hazard models to estimate the association between those ORDs and mortality and used simulations to project life years lost associated with the ORDs. We found that obesity-attributable comorbidities are associated with large decreases in life years and increases in mortality rates. The life years lost associated with ORDs is more marked for younger adults than older adults, for blacks than whites, for males than females, and for the more obese than the less obese. Using U.S. non-smoking adults aged 40 to 49 years as an example to illustrate percentage of the life years lost associated with ORDs, we found that the mean life years lost associated with ORDs for U.S. non-smoking black males aged 40 to 49 years with a body mass index above 40 kg/m(2) was 5.43 years, which translates to a 7.5% reduction in total life years. White males of the same age range and same degree of obesity lost 5.23 life years on average - a 6.8% reduction in total life years, followed by black females (5.04 years, a 6.5% reduction in life years), and white females (4.7 years, a 5.8% reduction in life years). Overall, ORDs increased chances of dying and lessened life years by 0.2 to 11.7 years depending on gender, race, BMI classification, and age.

Clinical characteristics, sepsis interventions and outcomes in the obese patients with septic shock: an international multicenter cohort study

Introduction

Data are sparse as to whether obesity influences the risk of death in critically ill patients with septic shock. We sought to examine the possible impact of obesity, as assessed by body mass index (BMI), on hospital mortality in septic shock patients.

Methods

We performed a nested cohort study within a retrospective database of patients with septic shock conducted in 28 medical centers in Canada, United States and Saudi Arabia between 1996 and 2008. Patients were classified according to the World Health Organization criteria for BMI. Multivariate logistic regression analysis was performed to evaluate the association between obesity and hospital mortality.

Results

Of the 8,670 patients with septic shock, 2,882 (33.2%) had height and weight data recorded at ICU admission and constituted the study group. Obese patients were more likely to have skin and soft tissue infections and less likely to have pneumonia with predominantly Gram-positive microorganisms. Crystalloid and colloid resuscitation fluids in the first six hours were given at significantly lower volumes per kg in the obese and very obese patients compared to underweight and normal weight patients (for crystalloids: 55.0 ± 40.1 ml/kg for underweight, 43.2 ± 33.4 for normal BMI, 37.1 ± 30.8 for obese and 27.7 ± 22.0 for very obese). Antimicrobial doses per kg were also different among BMI groups. Crude analysis showed that obese and very obese patients had lower hospital mortality compared to normal weight patients (odds ratio (OR) 0.80, 95% confidence interval (CI) 0.66 to 0.97 for obese and OR 0.61, 95% CI 0.44 to 0.85 for very obese patients). After adjusting for baseline characteristics and sepsis interventions, the association became non-significant (OR 0.80, 95% CI 0.62 to 1.02 for obese and OR 0.69, 95% CI 0.45 to 1.04 for very obese).

Conclusions

The obesity paradox (lower mortality in the obese) documented in other populations is also observed in septic shock. This may be related in part to differences in patient characteristics. However, the true paradox may lie in the variations in the sepsis interventions, such as the administration of resuscitation fluids and antimicrobial therapy. Considering the obesity epidemic and its impact on critical care, further studies are warranted to examine whether a weight-based approach to common therapeutic interventions in septic shock influences outcome.

Endocrine, metabolic, and morphologic alterations of adipose tissue during critical illness

OBJECTIVE

Observational studies report lower mortality in obese than in lean critically ill patients, an association referred to as the "obesity paradox." This may suggest a possible protective role for adipose tissue during severe illness.

DATA SOURCES

Relevant publications were identified based on searches in PubMed and on secondary searches of their bibliographies.

DATA SYNTHESIS

The endocrine functions of adipose tissue might play a role in the adaptation to critical illness. In the acute phase of illness, the anti-inflammatory adiponectin is reduced, whereas proinflammatory cytokine expression in adipose tissue is up-regulated. In the prolonged phase of critical illness, both adiponectin and anti-inflammatory cytokine production are increasing. Studies on the proinflammatory adipokine leptin during critical illness are inconsistent, possibly due to confounders such as gender, body mass index, and feeding. Morphologically, adipose tissue of critically ill patients reveals an increased number of newly differentiated, smaller adipocytes. Accentuated macrophage accumulation showing a phenotypic switch to M2-type suggests an adaptive response to the microenvironment of severe illness. Functionally, adipose tissue of critically ill patients develops an increased ability to store glucose and triglycerides.

CONCLUSIONS

Endocrine, metabolic, and morphologic properties of adipose tissue change during critical illness. These alterations may suggest a possible adaptive, protective role in optimizing chances of survival. More research is needed to understand the exact role of adipose tissue in lean vs. obese critically ill patients, in order to understand how illness-associated alterations contribute to the obesity paradox.