Obesity Paradox in Patients with Soft Tissue Infections Nationwide

Elissa Lin, Brigham and Women's Hospital; Katherine Williams, Brigham and Women's Hospital, Boston, MA; Wei Jiang, Brigham and Women's Hospital, Boston, MA; Vihas Patel, Brigham and Women's Hospital, Boston, MA; Naomi Shimizu, Brigham and Women's Hospital, Boston, MA; Zara Cooper, Brigham and Women's Hospital, Boston, MA; Joaquim Havens, Brigham and Women's Hospital, Boston, MA; Ali Salim, Brigham and Women's Hospital, Boston, MA; Reza Askari, Brigham & Women's Hospital

While the obesity paradox has been described in patients with certain chronic diseases, there are no studies that examine the effects of obesity among surgical patients with soft tissue infections (STI). Recently work by our group has shown a trend towards lower mortality in obese patients with necrotizing soft tissue infections. The purpose of this study was to study the relationship between obesity, types of nutritional support, and outcomes in patients with STI.

The obesity paradox is exhibited in patients with STI, despite the type of nutritional support received.

The Nationwide Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality database was used to retrospectively review patients with STI from 2006 to 2010. Patients with NIS Clinical Classification Codes for debridement of wound; infection or burn were included. Subjects were categorized by type of nutritional support received: artificial nutrition through tube feeds (enteral) or total parenteral nutrition (TPN), or non-artificial. We compared in-hospital mortality of non-obese vs. obese patients. A multivariate analysis using Chi-Square was conducted to identify predictors of mortality.

Of 31,325 patients with STI, 94.1% received non-artificial nutrition, 3.2% of patients received TPN, and 2.7% received tube feeds. All differences in mortality rates between obese vs. non-obese were statistically significant regardless of feeding practice (Table 1), and obese patients fared better than non-obese patients (p<0.001). Type of nutritional support and non-obesity were found to be significant predictors of mortality after controlling for all other factors. Regardless of the type of nutrition support, the odds of obese STI patients dying in the hospital were half (Odds Ratio 0.52) that of non-obese patients (95% CI 0.352-0.782).

Despite type of nutritional support, obesity is significantly protective of in-hospital mortality in patients with STI, suggesting that the obesity paradox exists in this patient population. Further work is required to validate the obesity paradox in this population.