The Association Between Body Mass Index and Clinical Outcomes in Acute Lung Injury

doi:10.1378/chest.06-1709

Chest

Volume 131, Issue 2, February 2007, Pages 342-348

https://doi.org/10.1378/chest.06-1709 Get rights and content

Abstract

Background:The association between body mass index (BMI) and outcomes in critically ill patients is unclear. Our objective was to determine the association between BMI and outcomes in a population-based cohort of patients with acute lung injury (ALI).

Methods:In a prospective cohort study of all ICU patients in King County, Washington, with ALI in 1 year (1999 to 2000), 825 patients had a BMI recorded. Using multivariate analysis, patients in the abnormal BMI groups were compared to normal patients in the following areas: mortality, hospital length of stay (LOS), ICU LOS, duration of mechanical ventilation, and discharge disposition.

Results:There was no mortality difference in any of the abnormal BMI groups compared to normal-weight patients. Severely obese patients had longer hospital LOS than normal-weight patients (mean increase, 10.5 days; 95% confidence interval [CI], 4.8 to 16.2 days; p < 0.001); this was accentuated when analysis was restricted to survivors (mean increase, 14.3 days; 95% CI, 7.1 to 21.6 days; p < 0.001). ICU LOS and duration of mechanical ventilation were also longer in the severely obese group when analysis was restricted to survivors (mean increase, 5.6 days; 95% CI, 1.3 to 9.8 days; p = 0.01; and mean increase, 4.1 days; 95% CI, 0.4 to 7.7 days, respectively; p = 0.03). Severely obese patients were more likely to be discharged to a rehabilitation or skilled nursing facility than to home.

Conclusions:BMI is not associated with mortality in patients with ALI, but severe obesity is associated with increased morbidity and resource utilization in the hospital and after discharge.

Section snippets

Materials and Methods

This study examined patients from the King County Lung Injury Project (KCLIP), a prospective cohort study of all patients with ALI admitted to all 18 hospitals with ICUs in King County, Washington, and 3 hospitals in adjacent counties between April 1999 and July 2000. A detailed description of the methods and hospitals is published elsewhere.²⁵All patients receiving mechanical ventilation at these 21 hospitals were screened for enrollment using the American-European Consensus Conference

Results

There were no significant demographic differences between the 825 included patients and the 288 patients excluded for lack of BMI data. Among the study population, we found no significant differences in gender or severity of illness between the BMI groups. There were significant differences in age, ALI risk factor, and tidal volume on day 3 (Table 1). Age steadily decreased as BMI increased; severely obese patients had a median age of 54.7 years, compared to 61.5 years in the normal-weight

Discussion

This study examines the relationship between BMI and outcomes in a large population-based cohort of patients with ALI. After adjustment for confounders, there was no association between mortality and BMI, but we did identify significantly increased morbidity, as measured by longer hospital and ICU LOS, longer duration of mechanical ventilation, and more frequent discharge to an SNF or rehabilitation facility in patients with BMI > 40 kg/m²compared to normal-weight patients. This was

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This research was partially supported by Specialized Center of Research Grant HL-30542 in Acute Lung Injury from the National Heart, Lung, and Blood Institute, National Institutes of Health, and by 8K12RR023265–02 from the National Institutes of Health Roadmap/National Center for Research Resources. None of the authors have conflicts of interest regarding this research.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml)

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Chest

Original Research: Critical Care MedicineThe Association Between Body Mass Index and Clinical Outcomes in Acute Lung Injury

Abstract

Section snippets

Materials and Methods

Results

Discussion

J Foot Ankle Surg

Ann Thorac Surg

Chest

Chest

Chest

Chest

Chest

Prevalence and trends in obesity among US adults, 1999–2000.

JAMA

Overweight and obesity in the United States: prevalence and trends, 1960–1994.

Int J Obes Relat Metab Disord

Ann Intern Med

Body-mass index and mortality in a prospective cohort of U.S. adults.

N Engl J Med

Obesity in adulthood and its consequences for life expectancy: a life-table analysis.

Ann Intern Med

Excess deaths associated with underweight, overweight, and obesity.

JAMA

Annual deaths attributable to obesity in the United States.

JAMA

Prospective identification of risk factors for wound infection after lower extremity oncologic surgery.

Ann Surg Oncol

Obesity is an independent risk factor of mortality in severely injured blunt trauma patients.

Arch Surg

Obesity and increased mortality in blunt trauma.

J Trauma

Original Research: Critical Care Medicine
The Association Between Body Mass Index and Clinical Outcomes in Acute Lung Injury