Letter to the Editor: “CT in necrotizing soft tissue infection: diagnostic criteria and comparison with LRINEC score”
by Manuela Gallo, Hernan Páez, Hernan Páez (firstname.lastname@example.org, email@example.com, firstname.lastname@example.org)CT in necrotizing soft tissue infection: diagnostic criteria and comparison with LRINEC score
Dear Editor in Chief,
We read with pleasure the article written by Bruls and Kwee entitled “CT in necrotizing soft tissue infection: diagnostic criteria and comparison with LRINEC score” . The author’s purpose was to examine the performance of computed tomography (CT) with respect to the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score in diagnosing necrotizing soft tissue infection (NSTI). They were able to identify that fluid along the deep fascia was a CT criterion that was significantly associated with NSTI, and it could be even more useful than LRINEC score.
Considering that the LRINEC score is based on serum parameters that could be altered with systemic inflammatory response, our main concern lies in that pre-test probability given by such score should be used carefully and with strict correlation with the physical exam to perform imaging studies like CT.
We want to highlight the fact that the authors found a significant difference in the frequency of fluid along the deep fascia with a small sample size, which can mean that there is a difference on the fluid along deep fascia and the LRINEC in patients with NSTI when is compared with non-NSTI . Nonetheless, this finding can be present in other entities like inflammatory myositis, non-infectious inflammatory fasciitis, or trauma , so we believe that this finding must be used carefully because even though it could be sensitive, it is unspecific.
Finally, the small sample size limits the results of the multivariate analysis. It has been shown that logistic models require a minimum sample size of 10 or more events relative to the number of variables being evaluated to reduce bias . The authors evaluated the presence of 6 CT findings in NSTI, which means that they probably needed a bigger sample size (at least 60 events) to be able to demonstrate a true association with a high statistical power.