Author: Dr. Jeny Tan-Creevy
Background:
Necrotizing soft tissue infections more commonly known as necrotizing fasciitis is a life-threatening diagnosis with a high risk for morbidity and mortality. Gold standard for diagnosis is surgical exploration, which unfortunately is difficult in the Emergency Department.
The study is a meta-analysis to investigate the accuracy of physical examination, imaging, and LRINEC score for necrotizing soft tissue infection.
Study Question:
What is the Accuracy of Physical Examination, Imaging, and the LRINEC Score for the Diagnosis of Necrotizing Soft Tissue Infection?
Data was gathered by two authors who searched for articles in MEDLINE, PubMed, EMBASE, Scopus, Web of Science, and the Cochrane Database of Systematic Reviews. Search terms included “necrotizing fasciitis,” “necrotizing skin and soft tissue infection,” “necrotizing soft tissue infection,” “gas gangrene,” and “Fournier’s gangrene.”
The authors reviewed 2290 initial citations composed of prospective and retrospective studies and ultimately chose 23 studies to be included in the meta-analysis.
Results:
Physical Examination
· Fever: Sensitivity 46%, Specificity 77%
· Hemorrhagic bullae: Sensitivity 25.2%, Specificity 95.8%
· Hypotension: Sensitivity 21%, Specificity 97.7%
Imaging
· Radiography: Sensitivity 48.9%, Specificity 94%
· CT (fascial gas only): Sensitivity 88.5%, Specificity 93.3%
· CT (fascial edema or enhancement or gas): Sensitivity 94.3%, Specificity 76.6%
LRINEC Score
· ≥ 6: Sensitivity 68.2%, Specificity 84.8%
· ≥ 8: Sensitivity 40.8%, Specificity 94.9%
Discussion:
This meta-analysis demonstrates that diagnosis of necrotizing fasciitis is difficult and the tools we have as Emergency Physicians do not have the best diagnostic accuracy to be able to rule out necrotizing fasciitis on their own given low sensitivities. CT scan looking for fascial edema or enhancement or gas appears to have the highest sensitivity of 94.3%. However, there is still room for error and a negative CT scan does not definitively exclude necrotizing fasciitis.
The LRINEC score is also not a good tool given poor sensitivities and specificities. In MDcalc, it specifically states, “If high suspicion for necrotizing fasciitis through clinical history and physical exam, do not calculate a LRINEC score and go straight to operative debridement.”
Studies chosen for this meta-analysis included retrospective cohort, prospective cohort, and retrospective case studies. There are no randomized studies. Also, individual studies in this meta-analysis had different inclusion criteria and it is unclear if investigators were blinded.
These studies also did not assess individual components of the LRINEC score.
Some studies also focused on different body parts. Therefore, physical exam might be better at certain locations compared to others and imaging tools may be chosen depending on what body part is considered resulting in skewed data.
The take home point is, if you have a high suspicion for Necrotizing Fasciitis, call surgery sooner rather than later because while antibiotic therapy is essential, prompt surgical management increases likelihood of survival.
Reference:
- April, M.D., Long, B., What is the Accuracy of Physical Examination, Imaging, and the LRINEC Score for the Diagnosis of Necrotizing Soft Tissue Infection? Annals of Emergency Medicine, 73 (1), 22-24.
- Fernando, S.M., Tran, A., Cheng, W., Rochwerg, B., Kyeremanteng, K., Seely, A. J. E., Inaba, K., Perry, J. Necrotizing Soft Tissue Infection: Diagnostic Accuracy of Physical Examination, Imaging, and LRINEC Score– A Systematic Review and Meta-Analysis. Annals of Surgery, 269 (1), 58-65.
- LRINEC Score for Necrotizing Soft Tissue Infection. (n.d.). Retrieved from https://www.mdcalc.com/lrinec-score-necrotizing-soft-tissue-infection