PURPOSE: Obesity has been proposed as a risk factor for poor outcomes in critically patients; however, its role remains unclear. Some studies have demonstrated a paradoxical protective effect on short term survival.
METHODS: Using the Nationwide Inpatient Sample from 2008, all patients with morbid obesity were identified using ICD-9-CM codes 278.01.Invasive mechanical ventilation (MV) was identified using ICD-9 procedure code 96.7. Outcome variables included all cause in-hospital-mortality and length of stay (LOS). The results were compared to non obese patients. Chi-square test and Wilcoxan sign-rank test was used to compare mortality and LOS respectively. Multivariate logistic regression was performed to adjust for confounding variables and determine odds ratios for mortality. The model adjusted for demographics, primary payer, hospital characteristics and Charlson's co-morbidity index. We also performed a subgroup analysis in those requiring prolonged MV (MV > 96hours).
RESULTS: Of 940,538 estimated hospital admissions requiring invasive MV during the year 2008 in the United States, the morbidly obese patients accounted for about 3.6%. The unadjusted all cause in hospital mortality in invasive mechanically ventilated morbidly obese patients was 19.5%, compared to 32.4% in non obese patients (p<0.001). The adjusted odds of mortality were 0.5 times lower (95% Confidence interval (CI): 0.47-0.54) in obese patients when compared to non obese. Proportion of morbidly obese patients requiring prolonged MV was not significantly different from non obese patients (41.3% vs. 40.4%; age and comorbidity adjusted OR 1.02 (0.97-1.07)). In patients requiring prolonged MV, unadjusted mortality was 20.3% in morbidly obese and 31.6% in non obese (OR 0.57; 95% CI 0.52-0.62). The LOS was 1 day shorter in morbidly obese patients (p<0.001).
CONCLUSIONS: Morbidly obese patients undergoing MV have significantly lower mortality than non obese patients. Proportion of morbidly obese patients requiring prolonged MV is no different from the non obese population.
CLINICAL IMPLICATIONS: Outcomes of mechanical ventilation in morbidly obese patient are not dismal and are possibly better than non obese patients.
DISCLOSURE: The following authors have nothing to disclose: Gagan Kumar, Gaurav Dagar, Amit Taneja, Jayshil Patel, Nilay Kumar, Rahul Nanchal
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