Risk factors for wound infection in outpatients with lower extremity burns

Author(s):
Husayn Ladhani; Brian Young; Sarah Posillico; Tammy Coffee; Anjay Khandelwal; Jeffrey Claridge

Background:

Majority of burns are small and treated on an outpatient basis, however, most of the literature on the incidence and risk factors for wound infection has focused on the inpatient population. We sought to evaluate the risk factors for wound infection in patients presenting to the outpatient burn clinic with lower-extremity (LE) burns.

Hypothesis:

We would be able to identify independent risk factors for wound infection in patients with LE burns, and specifically identify dressings associated with early wound infection.

Methods:

A retrospective study of all adult patients presenting to the outpatient burn clinic following a LE burn from 01/2014-07/2015 was performed. Patients admitted from first clinic visit were excluded. Data regarding demographics, comorbidities, injury characteristics, outpatient course, and outcomes was obtained from review of electronic medical records. Primary outcomes were wound infection at any time and early wound infection (by day 5). Multivariate logistic regression analysis was performed to identify independent risk factors for wound infection.

Results:

A total of 317 patients with LE burns were evaluated in our outpatient burn clinic with mean age of 42.9±16.7 yrs and median TBSA of 0.8% (IQR 0.3-1.5%); 22 patients had a component of full-thickness (FT) burn with median TBSA of 0.5% (IQR 0.2-1.0%). Scald burn (59.6%) was the most common mechanism of injury; 212 (66.9%) patients had below-the-knee (BTK) burn with median TBSA of 0.5% (IQR 0.2-1.0%). Median days to presentation after injury was 2 days (IQR 2-5 days).

The incidence of wound infection in LE burns was 14.5%, which increased to 18.9% in the BTK burn subgroup. Median time to infection was 5.0 days (IQR 4.0-8.3 days) and majority (60.9%) of patients developed would infection within first 5 days. Patients who developed wound infection at any time were more likely to have a FT burn (21.7% vs. 4.5%, p<0.001), and BTK burn (87.0% vs. 63.5%, p=0.002), but there was no difference in baseline demographics, comorbidities, etiology or size of burn, or days to presentation between the two groups. Multivariate logistic regression showed age (OR 1.02, CI 1.00-1.04), FT burn (OR 5.33, CI 2.09-13.62), and BTK burn (OR 3.42, CI 1.37-8.52) as independent risk factors for burn wound infection. Use of silver sulfadiazine (vs. other wound care) was associated with early wound infection (30.4% vs. 10.2%, p=0.005).

Conclusions:

Age, presence of FT burn, and BTK burn are independent risk factors for wound infection in the outpatient burn population with LE burns. Silver sulfadiazine was a factor associated with the development of early wound infection.