Incidence, comorbidity and mortality in patients with necrotising soft-tissue infections, 2005–2018: a Danish nationwide register-based cohort study

OBJECTIVE: To assess the incidence, comorbidities, treatment modalities and mortality in patients with necrotising soft-tissue infections (NSTIs) in Denmark. DESIGN: Nationwide population-based registry study. SETTING: Denmark. PARTICIPANTS: Danish residents with NSTI between 1 January 2005 and 31 August 2018. MAIN OUTCOME MEASURE: Incidence of disease per 100 000 person/year and all-cause mortality at day 90 obtained from Danish National Patient Registry and the Danish Civil Registration System. RESULTS: 1527 patients with NSTI were identified, yielding an incidence of 1.99 per 100 000 person/year. All-cause 30-day, 90-day and 1-year mortality were 19.4% (95% CI 17.4% to 21.5%), 25.2% (95% CI 23.1% to 27.5%) and 30.4% (95% CI 28.0% to 32.8%), respectively. Amputation occurred in 7% of the individuals. Diabetes was the most predominant comorbidity affecting 43% of the cohort, while 26% had no comorbidities. Higher age, female sex and increasing comorbidity index were found to be independent risk factors of mortality. Admission to high-volume hospitals was associated with improved survival (OR 0.59, 95% CI 0.45 to 0.77). Thirty-six per cent received hyperbaric oxygen therapy (HBOT) as an adjunctive therapy. No change in overall mortality was found over the studied time period. CONCLUSION: The present study found that in Denmark, the incidence of NSTI increased; mortality rates remained high and largely unaltered. Diabetes was the most common comorbidity, while higher age, female sex and increasing comorbidity index were associated to increased mortality. Survival was improved in those admitted to hospitals with more expertise in treating NSTI. In high-volume hospital, HBOT was associated with decreased odds for mortality.