NSTI Organisms and Regions: A Multicenter Study From the American Association for the Surgery of Trauma.

BACKGROUND: Conflicting data on the microbiology and epidemiology of necrotizing soft tissue infections (NSTIs) appear to stem from the heterogeneity in microbiology observed in regions across the United States. Our goal was to determine current differences in organism prevalence and outcomes for NSTI and non-necrotizing severe soft tissue infections across the United States. We hypothesized that there were geographical differences in organism prevalence that would lead to differences in outcomes. MATERIALS AND METHODS: This study was a retrospective multi-institutional trial from centers across the United States and Canada. Demographic, clinical, and outcomes data were collected. Bivariate and multivariable analyses were performed to determine the effects of region and microbiology on outcomes. RESULTS: A total of 622 patients were included in this study. Polymicrobial infections (45%) were the most prevalent infections in all regions. On bivariate analysis, Clostridium and polymicrobial infections had higher mean Laboratory Risk Indicator for Necrotizing Fasciitis scores and American Association for the Surgery of Trauma grades (P < 0.001 for both) than other organisms. Patients in the South were more likely to be uninsured and had worse unadjusted outcomes. In a risk-adjusted model, increasing American Association for the Surgery of Trauma grade was predictive of mortality (OR, 2.3; 95% CI, 1.6-3.1; P < 0.001), as was age ≥ 55 y (OR 2.7, 95% CI 1.3-5.3, P = 0.006), but region and organism type were not associated with mortality. CONCLUSIONS: We found important regional differences with respect to organism type and demographics. However, on risk-adjusted models, neither region nor organism type predicted mortality.

The EGS grading scale for skin and soft-tissue infections is predictive of poor outcomes: a multicenter validation study.

INTRODUCTION: Over the last 5 years, the American Association for the Surgery of Trauma has developed grading scales for emergency general surgery (EGS) diseases. In a previous validation study using diverticulitis, the grading scales were predictive of complications and length of stay. As EGS encompasses diverse diseases, the purpose of this study was to validate the grading scale concept against a different disease process with a higher associated mortality. We hypothesized that the grading scale would be predictive of complications, length of stay, and mortality in skin and soft-tissue infections (STIs). METHODS: This multi-institutional trial encompassed 12 centers. Data collected included demographic variables, disease characteristics, and outcomes such as mortality, overall complications, and hospital and ICU length of stay. The EGS scale for STI was used to grade each infection and two surgeons graded each case to evaluate inter-rater reliability. RESULTS: 1170 patients were included in this study. Inter-rater reliability was moderate (kappa coefficient 0.472-0.642, with 64-76% agreement). Higher grades (IV and V) corresponded to significantly higher Laboratory Risk Indicator for Necrotizing Fasciitis scores when compared with lower EGS grades. Patients with grade IV and V STI had significantly increased odds of all complications, as well as ICU and overall length of stay. These associations remained significant in logistic regression controlling for age, gender, comorbidities, mental status, and hospital-level volume. Grade V disease was significantly associated with mortality as well. CONCLUSION: This validation effort demonstrates that grade IV and V STI are significantly predictive of complications, hospital length of stay, and mortality. Though predictive ability does not improve linearly with STI grade, this is consistent with the clinical disease process in which lower grades represent cellulitis and abscess and higher grades are invasive infections. This second validation study confirms the EGS grading scale as predictive, and easily used, in disparate disease processes. LEVEL OF EVIDENCE: Prognostic/Epidemiologic retrospective multicenter trial, level III.