Obesity Is Not Associated with Antimicrobial Treatment Failure for Intra-Abdominal Infection

Abstract

Background: Obesity and commonly associated comorbidities are known risk factors for the development of infections. However, the intensity and duration of antimicrobial treatment are rarely conditioned on body mass index (BMI). In particular, the influence of obesity on failure of antimicrobial treatment for intra-abdominal infection (IAI) remains unknown. We hypothesized that obesity is associated with recurrent infectious complications in patients treated for IAI. Methods: Five hundred eighteen patients randomized to treatment in the Surgical Infection Society Study to Optimize Peritoneal Infection Therapy (STOP-IT) trial were evaluated. Patients were stratified by obese (BMI ‡30) versus non-obese (BMI ‡30) status. Descriptive comparisons were performed using Chi-square test, Fisher exact test, or Wilcoxon rank-sum tests as appropriate. Multivariable logistic regression using a priori selected variables was performed to assess the independent association between obesity and treatment failure in patients with IAI. Results: Overall, 198 (38.3%) of patients were obese (BMI ‡30) versus 319 (61.7%) who were non-obese. Mean antibiotic d and total hospital d were similar between both groups. Unadjusted outcomes of surgical site infection (9.1% vs. 6.9%, p = 0.36), recurrent intra-abdominal infection (16.2% vs. 13.8, p = 0.46), death (1.0% vs. 0.9%, p = 1.0), and a composite of all complications (25.3% vs. 19.8%, p = 0.14) were also similar between both groups. After controlling for appropriate demographics, comorbidities, severity of illness, treatment group, and duration of antimicrobial therapy, obesity was not independently associated with treatment failure (c-statistic: 0.64). Conclusions: Obesity is not associated with antimicrobial treatment failure among patients with IAI. These results suggest that obesity may not independently influence the need for longer duration of antimicrobial therapy in treatment of IAI versus non-obese patients.

The Surgical Infection Society Revised Guidelines on the Management of Intra-Abdominal Infection

“…As of yet, however, there are little data documenting improvements in clinical outcomes with use of these alternative dosing strategies. In fact, obesity has not been uniformly identified as a significant risk factor for an adverse outcome in patients with IAI [574,575], Continuous or prolonged (over 3-4 h) antibiotic infusion, as opposed to intermittent infusion (over 30-60 min), is a therapeutic tactic designed to take advantage of the pharmacokinetic and pharmacodynamic properties of specific antibiotic agents to maximize their clinical efficacy. The primary class of antibiotic agents that has been assessed using continuous or prolonged infusion are b-lactams.…”

Operative management of acute abdomen after bariatric surgery in the emergency setting: the OBA guidelines

“…The STOP-IT study showed that obesity is not associated with antimicrobial treatment failure among patients with IAIs. This suggests that obesity may not independently influence the need for longer duration of antimicrobial therapy in treatment of IAI compared to non-obese patients [ 102 ].…”

Impact of bodyweight-adjusted antimicrobial prophylaxis on surgical-site infection rates

“…Furthermore, standard AMP doses provide lower antibiotic concentrations per kilogram in overweight and obese patients compared with patients of normal bodyweight. Still, the results of a number of studies 25–28 including between 25 and 500 patients appear to have indicated that a standard AMP dose is sufficient to prevent SSI, even in obese patients. Possibly based on these reports, weight-adjusted AMP dosing is still debated 1–4 .…”

“…However, dosing guidelines for antibiotics most frequently used in AMP do not recommend weight-based dose adjustments 1 , 4 , 22 because the use of standardized doses is considered safe, effective, and convenient for most of the adult patient population 1 . Although double-dose AMP administration has been suggested for morbidly obese patients weighing at least 120 kg, or with a BMI of 40 kg/m 2 or higher 22–24 , studies 25–28 involving relatively small numbers of patients appear to suggest that standard AMP doses do successfully prevent SSI even in obese patients. Therefore, according to Centers for Disease Control and Prevention (CDC) guidelines for SSI prevention, the issue of weight-adjusted AMP dosing is still considered unresolved 1 , 4 .…”