Risk Stratification of Necrotizing Fasciitis Based on the Initial Procalcitonin Concentration: A Single Center Observational Study

Background: Necrotizing fasciitis (NF) is a potentially fatal subcutaneous tissue and fascia infection. We studied the role of serum procalcitonin in the identification and assessment of severity of sepsis in patients with NF. Methods: A retrospective analysis was conducted from January 2000 to December 2013 for all patients who admitted to surgical intensive care with provisional diagnosis of NF. Patients were categorized into four groups based on the initial procalcitonin concentrations (Group I:<0.5 low risk, Group II:0.5-<2 moderate risk, Group III: 2-<10 high risk, and Group IV: 10 ng/mL high likelihood of severe sepsis). Results: During the study period, 331 cases were identified to have NF with a mean age of 5114 years. Serum procalcitonin was tested in 62 cases (only between 2011 and December 2013) and all were positive (Group I: 22%, Group II: 18%, Group III: 21%, and Group IV: 39%). The most common affected regions were thigh and chest in Group II (46% and 9%, respectively), lower limbs in Group III (46%), and perineum and abdomen in Group IV (25% and 21%, respectively). In the four groups, 21 patients developed septic shock (Group I: 0%, Group II: 14%, Group III: 24%, and Group IV: 62%). The cut off procalcitonin value for septic shock was 5.6ng/mL. Using receiver-operating characteristic curve, this cut off with the Area under the Curve (AUC) of 0.77 was found to have sensitivity 81% and specificity 67%. Sequential Organ Failure Assessment (SOFA) score was substantially greater in Group III and Group IV in comparison to Group I and Group II, p=0.006. Procalcitonin levels were correlated well with SOFA score (r=0.34, p=0.007). There were 17 deaths in the four groups (Group I: 6%, Group II: 23%, Group III: 12%, and Group IV: 59%). Conclusion: Initial procalcitonin concentration in NF carries an important prognostic value and it correlates well with SOFA score and can predict the development of septic shock early in patients with NF.