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.