We thank Dr Schnall, et. al. for sharing their large experience of 99 patients
with necrotizing fasciitis. In their series, the most significant
predictor of adverse outcome was patient age and the presence of sepsis
with positive blood cultures.
We would like to clarify the findings of our study. Of the twelve factors
previously reported to adversely affect survival, three factors
( patient age, the presence of 2 or more associated co-morbidites and
a delay of operative débridement beyond 24 hours) were noted to be
associated with patient mortality on univariate analysis. Because of the
potential of inter-dependence between these factors, a more suitable test
of significance would reside in multivariate analysis of the factors that were
significant in the univariate model. We performed this analysis and found that the only
factor that was independently associated with mortality was delayed
operative débridement of beyond 24 hours after admission.
This was also the strongest predictive
factor noted by McHenry et al [1]. The association of intravenous drug
abuse complicated by necrotizing fasciitis and mortality was not analyzed
as only one such patient presented in this manner. The presence of
diabetes in itself was not a predictor of mortality in our study.
Dr Schnall noted in his series that adverse predictors of
outcome included patient age and the presence of positive blood cultures
taken at admission. While we did not analyze the association of positive
blood cultures with mortality in necrotizing fasciitis, this finding is of
interest and deserves further discussion. The angiothrombotic liquefactive
necrosis of the fascia that characterizes necrotizing fasciitis suggests that
delivery of antibiotics to the infected fascia will be
compromised. Progression of infection despite intravenous antimicrobials
is therefore the rule in necrotizing fasciitis, underscoring the need for
aggressive surgical débridement. However, antimicrobial therapy reduces the
bacterial load in the circulation and may decrease the incidence of organ
failure.
The mortality noted in our series was 21.3 %. This was somewhat
lower than many series reported in the literature [1]. We postulate that
this may be due to the increasing use of broad-spectrum antibiotics in the
pre-hospital setting by primary care physicians (70.8 % of our patients
were given antibiotics empirically prior to admission). Patients who delay
seeking medical attention and are admitted with severe sepsis without
antimicrobial therapy are more likely to yield positive cultures in the
blood. One could speculate that patients with bacteremia may have more
severe sepsis and multi-organ involvement, and therefore a higher
mortality. This is consistent with Dr Schnall’s finding of association of
bacteremia with mortality. Blood cultures obtained at admission
are certainly helpful not only in the prediction of a more fulminant course
but are an indispensable guide for appropriate antimicrobial selection.
We reiterate that early recognition and débridement are the
cornerstones of management and should be the focus of our approach to this
dreaded disease. However, as we have shown, necrotizing fasciitis is often
clinically indistinguishable from other more benign soft-tissue infections
such as cellulitis. While modalities such as frozen section biopsy and
magnetic resonance imaging (MRI) of the affected part have been shown to
be capable of detecting early cases of necrotizing fasciitis, these
investigations are not readily available on an emergent basis at many
centers [2, 3]. They are also costly if performed for all suspicious cases
of soft-tissue infections. We therefore developed a diagnostic scoring
system based on laboratory parameters routinely performed for all soft-
tissue infections and readily available on admission (complete blood
count, electrolytes and C-reactive protein) [4].We think that this
diagnostic scoring system, the LRINEC (laboratory risk indicator for
necrotizing fasciitis) score is capable of distinguishing even early cases
of necrotizing fasciitis from other soft-tissue infections. With a focused
approach in the evaluation of soft-tissue infections, we hope that
necrotizing fasciitis can be detected even early in its evolution and
survival improved.
Chin-Ho Wong, MBBS, MRCSEd
Department of Orthopedic Surgery
Changi General Hospital
2 Simei Street 3,
Singapore 529889
E-Mail: wchinho@hotmail.com
References:
1. McHenry CR, Piotrowski JJ, Petrinic D, Drazen P, Mark AM. Determinants
of mortality in necrotizing soft tissue infections. Ann Surg 1995; 304-08.
2. Schmid MR, Kossmann T, Duewell S. Differentiation of necrotizing
fasciitis from cellulites using MR imaging. AJR Am J Roentgenol 1998; 170:
615-20.
3. Stamenkovic I, Lew PD. Early recognition of potentially fatal
necrotizing fasciitis: The use of frozen section biopsy. N Eng J Med.
1984; 310: 1689-93.
4. Wong CH, Khin LW, Heng KS, Low CO. Risk Stratifying Strategy in the
Management of Necrotizing Fasciitis using a Novel Inflammatory Index.
Abstract in European Surgical Research 2003; 35: 235. Presented at the
38th Congress of the European Society of Surgical Research.
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