Clinical characteristics, sepsis interventions and outcomes in the obese patients with septic shock: an international multicenter cohort study
1 Intensive Care Department, King Abdulaziz Medical City, Riyadh11426, Saudi Arabia
2 Department of Epidemiology and Biostatistics, King Abdullah International Medical Research Center, Riyadh11426, Saudi Arabia
3 Department of Experimental Medicine, King Abdullah International Medical Research Center, Riyadh 11426, Saudi Arabia
4 Critical Care Medicine, Moses H. Cone Memorial Hospital, Greensboro, NC 27403, USA
5 Heart and Vascular Hospital, UMDNJ, Hackensack University Medical Center, 30 Prospect Avenue, Hackensack, New Jersey 07601, USA
6 Geisinger Medical Center, 100 North Academy Ave Danville, PA 17822-0111, USA
7 Royal Columbian Hospital, 330 E Columbia St New Westminster, BC Canada V3L 3W7
8 Cooper Hospital/University Medical Center,, 1 Cooper Plaza, Camden NJ, USA 08103
9 Richmond Hospital, 7000 Westminster Highway, Richmond, B.C. V6X 1A2 Canada
10 Laurentian University, 935 Ramsey Lake Rd. Sudbury, Ontario Canada P3E 2C6
11 Section of Critical Care Medicine and Section of Infectious Diseases, Health Sciences Center and St. Boniface Hospital, University of Manitoba, Canada. 700 William Ave, Winnipeg, MB Canada R3P-1R9
Critical Care 2013, 17:R72 doi:10.1186/cc12680Published: 17 April 2013
Data are sparse as to whether obesity influences the risk of death in critically ill patients with septic shock. We sought to examine the possible impact of obesity, as assessed by body mass index (BMI), on hospital mortality in septic shock patients.
We performed a nested cohort study within a retrospective database of patients with septic shock conducted in 28 medical centers in Canada, United States and Saudi Arabia between 1996 and 2008. Patients were classified according to the World Health Organization criteria for BMI. Multivariate logistic regression analysis was performed to evaluate the association between obesity and hospital mortality.
Of the 8,670 patients with septic shock, 2,882 (33.2%) had height and weight data recorded at ICU admission and constituted the study group. Obese patients were more likely to have skin and soft tissue infections and less likely to have pneumonia with predominantly Gram-positive microorganisms. Crystalloid and colloid resuscitation fluids in the first six hours were given at significantly lower volumes per kg in the obese and very obese patients compared to underweight and normal weight patients (for crystalloids: 55.0 ± 40.1 ml/kg for underweight, 43.2 ± 33.4 for normal BMI, 37.1 ± 30.8 for obese and 27.7 ± 22.0 for very obese). Antimicrobial doses per kg were also different among BMI groups. Crude analysis showed that obese and very obese patients had lower hospital mortality compared to normal weight patients (odds ratio (OR) 0.80, 95% confidence interval (CI) 0.66 to 0.97 for obese and OR 0.61, 95% CI 0.44 to 0.85 for very obese patients). After adjusting for baseline characteristics and sepsis interventions, the association became non-significant (OR 0.80, 95% CI 0.62 to 1.02 for obese and OR 0.69, 95% CI 0.45 to 1.04 for very obese).
The obesity paradox (lower mortality in the obese) documented in other populations is also observed in septic shock. This may be related in part to differences in patient characteristics. However, the true paradox may lie in the variations in the sepsis interventions, such as the administration of resuscitation fluids and antimicrobial therapy. Considering the obesity epidemic and its impact on critical care, further studies are warranted to examine whether a weight-based approach to common therapeutic interventions in septic shock influences outcome.