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

Effects of obesity on short-term mortality in patients with acute heart failure under different nutritional status

BACKGROUND

Increased body mass index (BMI) is associated with better survival in patients with acute heart failure (AHF), which is a paradoxical phenomenon. However, it is unclear whether different nutritional status affects this association.

METHODS

1325 patients with AHF from the Medical Information Mart for Intensive Care III database were retrospectively included. Nutritional status was assessed by serum albumin (SA) and prognostic nutritional index (PNI). Patients were divided into High-SA (≥ 3.5 g/dL) and Low-SA groups (< 3.5 g/dL), and they also were divided into High-PNI (≥ 38) and Low-PNI groups (< 38). Propensity-score matching (PSM) was used to control for the effect of baseline confounding factors, multifactor regression model was adopted to assess the association of nutritional status, BMI, and outcomes in AHF patients.

RESULTS

Of the 1325 patients (mean age 72.4 ± 13.1 years), 52.1% (n = 690) were male, 13.1% (n = 173) died in hospital and 23.5% (n = 311) died within 90 days. Before PSM, after adjusting for potential confounders, in the High-SA population, compared with the under/normal BMI group, overweight and obesity were negatively correlated with 90-day mortality, with adjusted hazard ratios (HR) of 0.47, 95% confidence interval (CI) (0.30-0.74), P = 0.001; HR 0.45, 95%CI (0.28-0.72), P = 0.001, respectively. However, this correlation was much attenuated in the Low-SA group (overweight BMI: HR 1.06, 95%CI 0.75-1.50, P = 0.744; obese BMI: HR 0.86, 95%CI 0.59-1.24, P = 0.413). After PSM, those who were overweight or obese in the High-SA group had a 50-58% reduction in 90-day risk of death, while the protective effect disappeared in the Low-SA group (HR 1.09, 95% CI 0.70-1.71; HR 1.02, 95%CI 0.66 - 0.59). Similarly, results were similar in analyses using PNI as a nutritional assessment criterion.

CONCLUSION

Overweight or Obesity was associated with lower short-term mortality in well-nourished AHF patients, whereas this association was significantly attenuated or even disappeared in malnourished patients. Therefore, further research is needed for weight loss recommendations for malnourished obese patients with AHF.

Differences by age in the obesity paradox in severe burns

BACKGROUND

Many studies show a "obesity paradox", which seems to protect against death. Whether an obesity paradox space is present in severe burn patients remains a matter of great debate. Most research on the obesity paradox of burn injuries is classified by body mass index (BMI) rather than by age.

OBJECTIVE

To investigate whether the obesity paradox exists in severe burn patients stratified by age.

METHODS

Retrospective analysis was performed on 490 patients with severe burns who were ≥ 18 years of age and were admitted to Fujian Medical University Union Hospital from January 2005 to December 2020. Demographic and clinical characteristics were collected, including age, BMI, total body surface area (TBSA), presence of inhalation injury, abbreviated burn severity index (ABSI) score, diabetes comorbidities, hypertension comorbidities, and in-hospital mortality. The patients were divided into the younger group (18 ≤ age<65 years) and the older group (age ≥ 65 years). The important variables of the two groups were compared. The predictive value of BMI stratified by age on in-hospital mortality was evaluated by binary logistic regression analysis and the Cochran's and Mantel-Haenszel statistics.

RESULTS

A total of 490 patients were selected for this study, and were divided into the younger group (413) and the elderly group (77) according to their ages. In the younger group, logistic regression analyses indicated that high BMI remained significantly and independently associated with decreased in-hospital mortality (P = 0.021). That is, in-hospital mortality decreased by 17.8% when BMI increased by 1 kg/m². In the older group, BMI was not associated with in-hospital mortality (P = 0.808). In the younger group, the results of Pearson's chi-square test was less than 0.05, indicating a correlation between BMI and prognosis. In the older group, the conclusion was contrary with, no correlation between BMI and prognosis. If the confounding factors of age were not considered, this results in no correlation between BMI and prognosis. In the younger group, the survival/death ratio of patients with overweight and obesity was 2.078 times that of patients with normal weight.

CONCLUSION

In this study of patients with severe burns, overweight and obesity had protective effect on burn injury in the younger group (18 ≤ age<65 years), but not in the older group (age ≥ 65 years). Investigating the obesity paradox in burn patients needs to consider age differences. However, multicentre clinical trials are needed to verify the results.

Obesity protects against sepsis-induced and norepinephrine-induced white adipose tissue browning

Sepsis is a dysregulated systemic response to infection and can lead to organ damage and death. Obesity is a significant problem worldwide and affects outcomes from sepsis. Our laboratory demonstrated that white adipose tissue (WAT) undergoes browning during sepsis, a process whereby WAT adopts a brown adipose tissue phenotype. However, this browning process was not observed in obese mice during sepsis. White adipose tissue browning is detrimental in patients with burn injury and cancer. We hypothesize that norepinephrine (NE) induces WAT browning in nonobese mice but not in obese mice similarly to sepsis-induced WAT browning. Six-week-old C57BL/6 male mice were randomized to a high-fat diet or normal diet. After 6-7 wk of feeding, polymicrobial sepsis was induced by cecal ligation and puncture (CLP). Norepinephrine was administered intraperitoneally via osmotic minipumps for 18 h or 72 h (no CLP) at which time tissue and plasma were harvested. Controls were mice that underwent CLP (no NE) with 18-h harvest. A separate group of mice underwent pretreatment with NE or vehicle infusion for 72 h, CLP was performed, and at 18 h had tissue and plasma harvested. Sepsis resulted in significant weight loss in both nonobese and obese mice. NE treatment alone caused weight loss in obese mice. Septic nonobese mice had higher uncoupling protein-1 (UCP1) expression compared with control and obese septic mice. NE treatment increased UCP1 expression in nonobese, but not obese mice. NE-treated obese septic mice had lower lung myeloperoxidase (MPO) activity, alanine aminotransferase (ALT), aspartate aminotransferase (AST), TNFα, and IL-6 levels compared with NE-treated nonobese septic mice. Obesity protects mice from septic-induced and NE-induced WAT browning.NEW & NOTEWORTHY White adipose tissue browning is detrimental in patients with burn injury and cancer. WAT browning occurs in nonobese mice and can be induced by β receptor norepinephrine infusion, but obese mice are resistant to sepsis-induced and norepinephrine-induced WAT browning. We propose that the lack of WAT browning and unchanged inflammatory cytokine response may contribute to the protection of obese mice from sepsis.