Body Mass Index and Intensive Care Unit Outcomes in African American Patients

Associations between body mass index, biological age and frailty in the critically ill

BACKGROUND

The relationship between body mass index (BMI) and outcomes in the acute care setting is controversial, with evidence suggesting that obesity is either protective - which is also called obesity paradox - or associated with worse outcomes. The purpose of this study was to assess whether BMI was related to frailty and biological age, and whether BMI remained predictive of mortality after adjusting for frailty and biological age.

SUBJECTS

Of the 2950 patients who had a biological age estimated on admission to the intensive care unit, 877 (30 %) also had BMI and frailty data available for further analysis in this retrospective cohort study.

METHODS

Biological age of each patient was estimated using the Levine PhenoAge model based on results of nine blood tests that were reflective of DNA methylation. Biological age in excess of chronological age was then indexed to the local study context by a linear regression to generate the residuals. The associations between BMI, clinical frailty scale, and the residuals were first analyzed using univariable analyses. Their associations with mortality were then assessed by multivariable analysis, including the use of a 3-knot restricted cubic spline function to allow non-linearity.

RESULTS

Both frailty (p = 0.003) and the residuals of the biological age (p = 0.001) were related to BMI in a U-shaped fashion. BMI was not related to hospital mortality, but both frailty (p = 0.015) and the residuals of biological age (OR per decade older than chronological age 1.50, 95 % confidence interval [CI] 1.04-2.18; p = 0.031) were predictive of mortality after adjusting for chronological age, diabetes mellitus and severity of acute illness.

CONCLUSIONS

BMI was significantly associated with both frailty and biological age in a U-shaped fashion but only the latter two were related to mortality. These results may, in part, explain why obesity paradox could be observed in some studies.

Appendectomy Hospital Stay: No Difference in Obese Adult or Pediatric Patient Length of Stay Compared to Nonobese Patients

Background: Studies of adult and pediatric patients undergoing appendectomy have reported variable outcomes and operative metrics related to the effect of obesity. The purpose of this study was to investigate the effect of obesity in adult and pediatric patients undergoing appendectomy at our institution. Methods: This single-center retrospective study evaluated the relationship between length of hospital stay for appendectomy and body mass index (BMI). Data obtained from the electronic medical record included age, sex, weight, height, BMI, the number of hours the patient experienced symptoms prior to presentation to the emergency room, the number of hours the patient was admitted prior to surgery, the number of hours of hospital admission after surgery, perforated appendix, preoperative comorbidities, and evidence of preoperative sepsis. Results: During the 3-year study period, 118 adults and 38 children who underwent appendectomy composed the study groups. Patients were stratified by obese and nonobese, with obesity defined as BMI ≥30.0 kg/m². In adults, we found no significant difference between length of stay in obese (n=45) and nonobese (n=73) patients (79.6 ± 65.5 hours vs 101.6 ± 123.0 hours; P=0.21). In children, we found no significant difference between length of stay in obese (n=9) and nonobese (n=29) patients (92.9 ± 64.6 hours vs 109.0 ± 93.5 hours; P=0.54). Conclusion: Obesity did not affect length of stay in adults and children who underwent appendectomy in the present series.

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.

Dose-Response Meta-Analysis of the Impact of Body Mass Index on Mortality in the Intensive Care Unit

INTRODUCTION

Both low and high body mass index (BMI) are associated with mortality in the intensive care unit (ICU). Although many studies have been done to determine the relationship between BMI and risk of mortality in the ICU, their results were inconsistent. This study aimed to conduct a dose-response meta-analysis of published observational studies to assess the effect of BMI on the risk of mortality in patients admitted to the ICU.

METHODS

PubMed, Scopus, and Google Scholar were searched to identify articles up to May 2019. A total of 31 relevant articles, with 238,961 patients and a follow-up period of 1 month to 11 years, were analyzed.

RESULTS

Linear analysis showed a 0.6% decrease in mortality rate per unit (kg/m² ) increase in BMI (odds ratio: 0.99; 95% CI, 0.98-0.99). In addition, nonlinear analysis showed a decrease in risk of mortality for a BMI of 35 (P < .001) and then increased the risk of mortality with a BMI > 35 (P < .001).

CONCLUSION

This dose-response meta-analysis revealed that a BMI ≤ 35 can be a protective agent against mortality, but a BMI > 35 is a life-threatening factor in patients admitted to the ICU.

A latent class analysis of prolonged mechanical ventilation patients at a long-term acute care hospital: Subtype differences in clinical outcomes

RATIONALE

Patients on prolonged mechanical ventilation (PMV) at Long-Term Acute Care Hospital's (LTACHs) are clinically heterogeneous making it difficult to manage care and predict clinical outcomes.

OBJECTIVES

Identify and describe subgroups of patients on PMV at LTACHs and examine for group differences.

METHODS

Latent class analysis was completed on data obtained during medical record review at Midwestern LTACH.

MAIN RESULTS

A three-class solution was identified. Class 1 contained young, obese patients with low clinical and co-morbid burden; Class 2 contained the oldest patients with low clinical burden but multiple co-morbid conditions; Class 3 contained patients with multiple clinical and co-morbid burdens. There were no differences in LTACH length of stay [F(2,246) = 2.243, p = 0.108] or number of ventilator days [F(2,246) = 0.641, p = 0.528]. Class 3 patients were less likely to wean from mechanical ventilation [χ²(2, N = 249) = 25.48, p < 0.001] and more likely to die [χ²(2, N = 249) = 23.68, p < 0.001].

CONCLUSION

Patient subgroups can be described that predict clinical outcomes. Class 3 patients are at higher risk for poor clinical outcomes when compared to patients in Class 1 or Class 2.

Is body mass index associated with outcomes of mechanically ventilated adult patients in intensive critical units? A systematic review and meta-analysis

BACKGROUND

Obesity paradox refers to lower mortality in subjects with higher body mass index (BMI), and has been documented under a variety of condition. However, whether obesity paradox exists in adults requiring mechanical ventilation in intensive critical units (ICU) remains controversial.

METHODS

MEDLINE, EMBASE, China Biology Medicine disc (CBM) and CINAHL electronic databases were searched from the earliest available date to July 2017, using the following search terms: "body weight", "body mass index", "overweight" or "obesity" and "ventilator", "mechanically ventilated", "mechanical ventilation", without language restriction. Subjects were divided into the following categories based on BMI (kg/m2): underweight, < 18.5 kg/m2; normal, 18.5-24.9 kg/m2; overweight, BMI 25-29.9 kg/m2; obese, 30-39.9 kg/m2; and severely obese > 40 kg/m2. The primary outcome was mortality, and included ICU mortality, hospital mortality, short-term mortality (<6 months), and long-term mortality (6 months or beyond). Secondary outcomes included duration of mechanical ventilation, length of stay (LOS) in ICU and hospital. A random-effects model was used for data analyses. Risk of bias was assessed using the Newcastle-Ottawa quality assessment scale.

RESULTS

A total of 15,729 articles were screened. The final analysis included 23 articles (199,421 subjects). In comparison to non-obese patients, obese patients had lower ICU mortality (odds ratio (OR) 0.88, 95% CI 0.0.84-0.92, I2 = 0%), hospital mortality (OR 0.83, 95% CI 0.74-0.93, I2 = 52%), short-term mortality (OR 0.81, 95% CI 0.74-0.88, I2 = 0%) as well as long-term mortality (OR 0.69, 95% CI 0.60-0.79, I2 = 0%). In comparison to subjects with normal BMI, obese patients had lower ICU mortality (OR 0.88, 95% CI 0.82-0.93, I2 = 5%). Hospital mortality was lower in severely obese and obese subjects (OR 0.71, 95% CI 0.53-0.94, I2 = 74%, and OR 0.80, 95% CI 0.73-0.89, I2 = 30%). Short-term mortality was lower in overweight and obese subjects (OR 0.82, 95% CI 0.75-0.90, I2 = 0%, and, OR 0.75, 95% CI 0.66-0.84, I2 = 8%, respectively). Long-term mortality was lower in severely obese, obese and overweight subjects (OR 0.39, 95% CI 0.18-0.83, and OR 0.63, 95% CI 0.46-0.86, I2 = 56%, and OR 0.66, 95% CI 0.57-0.77, I2 = 0%). All 4 mortality measures were higher in underweight subjects than in subjects with normal BMI. Obese subjects had significantly longer duration on mechanical ventilation than non-obese group (mean difference (MD) 0.48, 95% CI 0.16-0.80, I2 = 37%), In comparison to subjects with normal BMI, severely obese BMI had significantly longer time in mechanical ventilation (MD 1.10, 95% CI 0.38-1.83, I2 = 47%). Hospital LOS did not differ between obese and non-obese patients (MD 0.05, 95% CI -0.52 to 0.50, I2 = 80%). Obese patients had longer ICU LOS than non-obese patients (MD 0.38, 95% CI 0.17-0.59, I2 = 70%). Hospital LOS and ICU LOS did not differ significantly in subjects with different BMI status.

CONCLUSIONS

In ICU patients receiving mechanical ventilation, higher BMI is associated with lower mortality and longer duration on mechanical ventilation.