PURPOSE: Obesity is a major public health problem in the United States, and its prevalence in the intensive care unit (ICU) population is approximately 25%. Management of critical illness in obese patients is challenging; however, it is not known whether obesity influences clinical outcomes in this population. In the present study, we tested the hypothesis that obesity is an independent risk factor for all-cause ICU mortality and ICU length of stay (LOS).
METHODS: We retrospectively reviewed the medical records of 702 patients discharged from the ICU between March 2010 and August 2010. Patients were grouped into 3 categories based on body mass index (BMI): underweight (<18 kg/m2), non-obese (18-29.9 kg/m2), and obese (≥30 kg/m2). We measured APACHE IV scores and identified obesity-related comorbidities for each patient.
RESULTS: In univariate analyses, all-cause ICU mortality (OR = 1.072, p = 0.807) and ICU LOS (5.36 versus 5.39 days, p = 0.166) were not significantly different between obese and non-obese patients; however, obese patients had significantly lower APACHE IV scores (52.7 versus 57.4, p = 0.005) than their non-obese counterparts. After controlling for severity of illness, we found no statistically significant association between all-cause mortality (OR = 0.903, p = 0.895) and ICU LOS (p = 0.499). In our analyses of secondary outcomes, obese patients were 47% more likely to be hyperglycemic than non-obese patients (p = 0.024), after accounting for disease acuity and co-morbidities. We also identified a trend toward higher peak airway pressures in obese patients (p = 0.096).
CONCLUSIONS: Although obesity was not associated with ICU mortality or ICU LOS, it was associated with poor glycemic control. Additional research is needed to validate this observation, and determine whether hyperglycemia influences the detrimental effects of obesity on acute organ system function in the critically ill. APACHE IV scores do not account for obesity and may underestimate disease acuity in obese critically ill patients.
CLINICAL IMPLICATIONS: As we may be underestimating the effect of obesity on ICU outcomes, it may be beneficial to adjust current risk stratification and severity measures to account for obesity.
DISCLOSURE: The following authors have nothing to disclose: George Nguyen, Cynthia Kim, Michael de la Cruz, Shanti Mikkilineni, Amit Borah, Qudsia Shaikh, Shirish Amrutia, James Gasperino
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