Predisposing factors of necrotizing fasciitis with comparison to cellulitis in Taiwan: A nationwide population-based case-control study.

BACKGROUND: Necrotizing fasciitis (NF) is a life-threatening soft tissue infection with low incidence that requires prompt surgery. In the initial stage, it is difficult to distinguish NF and cellulitis, and limited population-based reports are available.

METHODS: We queried inpatient data sets of National Health Institute Research Database in Taiwan from 2002 to 2011 for all patients with diagnoses of NF. Of them, only patients who underwent surgeries and had been admitted to intensive care units were included as the study group. Age and gender-matched patients with admission diagnoses of cellulitis were enrolled in a ratio of 1:4 as the control group. We calculated annual incidence, mortality rate, risk factors and predictors of mortality of NF.

RESULTS: The study group consisted of 7391 NF patients. Among them, 4715 patients (64%) were man and 2676 (36%) were women. The overall annual incidence of NF was 3.26 hospitalizations per 100,000 person-years, which rose with age with male predominance. The in-hospital mortality rate, which also rose with age, was 32.2%. Diabetes mellitus (adjusted odds ratio, 2.93; 95% confidence interval, 2.77-3.11; P value < 0.0001), alcoholism (2.64; 2.27-3.08; P < .0001), and chronic kidney disease (1.98; 1.84-2.14; P < .001) were identified as risk factors. Chronic kidney disease (1.86; 1.64-2.10; P < .001) and liver cirrhosis (1.68; 1.50-1.88; P < .001) were identified as predictors of in-hospital mortality.

CONCLUSION: Age and the presence of chronic diseases are major risk factors as well as prognostic factors of NF in Taiwan. Diabetes mellitus increases the risk of NF, but does not adversely affect the outcome.