Risk factors for clinical failure in patients hospitalized with cellulitis/cutaneous abscess

Objectives:

To evaluate clinical outcomes and risk factors associated with clinical failure in patients hospitalized with cellulitis with or without cutaneous abscess.

 Methods:

We performed a retrospective cohort study of consecutive adults admitted for cellulitis/cutaneous abscess July 1, 2009 through June 30, 2010. Descriptive statistics were used to summarize the demographics, microbiologic etiology, and antimicrobial therapy utilization. Binary logistic and multivariate stepwise regression analyses were performed to identify risk factors for treatment failure among evaluable patients.

Results:

A total of 210 patients met inclusion criteria during the study period. Our patient population was relatively obese (average weight=101 kg and BMI=34) with multiple co-morbid conditions. Among evaluable patients, clinical failure occurred in 34 (32.1%) patients. Factors associated with clinical failure upon univariate regression analysis included weight over 100kg (OR=5.89, P=0.014), trauma (OR=4.68, P=0.048), inadequate empiric therapy (OR=11.66, P=0.025), previous antimicrobial therapy in last 90 days (OR=5.10, P=0.010) and low discharge dosing (OR=3.10, P=0.049). Morbid obesity (BMI ≥ 40), MRSA on culture, duration of therapy of 7 days or longer, and low empiric dosing trended towards being risk factors for clinical failure.  Independent predictors of clinical failure upon multivariate regression analysis were weight greater than 100kg, severity of illness, recent antimicrobial therapy, and inadequate empiric therapy. Further subgroup analysis demonstrated that morbidly obese patients with cellulitis were at higher risk for clinical failure if they were discharged on a low oral dose of clindamycin or trimethoprim/sulfamethoxazole (P=0.0019).

 Conclusion:

Appropriate antimicrobial selection and dosing are essential to optimize clinical outcomes among patients with cellulitis/cutaneous abscess. Obese individuals may be at particular risk for clinical failure secondary to inadequate dosing of antimicrobial therapy.