PURPOSE: Studies of the association between body mass index (BMI) and survival have yielded variable results in mixed populations of critically ill patients. Because of the association between obesity and increased levels of inflammatory mediators, we decided to evaluate the relationship between BMI, survival, intensive care unit (ICU) and hospital outcomes in critically ill patients with blood stream infections (BSI).
METHODS: We retrospectively reviewed adult patients(≥18 years)in a 16 bed medical-surgical ICU with ≥1 positive blood culture(BC)between 1/02 and 12/05. Those with BSI’s (a high grade pathogen in at least one BC or common skin flora in ≥2BC’s) were selected for further analysis. The patients were grouped according to BMI in ranges that represented normal, overweight, obese, and morbidly obese subtypes. Between group comparisons were made for survival to hospital discharge, APACHE II severity scores, hosptial length of stay (LOS)and ICU LOS for all patients and for survivors only. Values are given as mean ± SD. ANOVA, Kruskal-Wallis and Chi-square tests were used for analysis. P<0.05 was considered to be statistically significant.
RESULTS: 185 patients were identified with BSI’s. There were only 2 patients with sub-normal BMI (<18). These patients were excluded from analysis. 38% of the 183 remaining patients died during the hospitalization. Patients with BMI’s in the obese range (>30) had increased survival compared to patients who were non-obese (P=0.028). The survival advantage for morbidly obese patients (BMI>40) was maintained. There was a trend toward longer hospital LOS’s for the morbidly obese patients who survived.
CONCLUSION: Blood stream infections have a high mortality rate in ICU patients. Obese patients have a survival advantage in this condition. This advantage is maintained for the morbidly obese. Obesity may be associated with protective alterations in the immune or metabolic response to serious infections and inflammation.
CLINICAL IMPLICATIONS: Characterization of the inflammatory and metabolic response to blood stream infections in obese patients may lead to the development of effective treatment approaches for patients of all body types.
DISCLOSURE: Luis Carlos Murillo, None.