Cellulitis in Obesity: Adverse Outcomes Affected by Increases in Body Mass Index.

PURPOSE: Cellulitis in obese patients is associated with increased rates of treatment failure compared to those with normal body mass index (BMI); however, patients have not been extensively studied in the outpatient environment or stratified based on range of obesity and associated risk factors. This study looked at antibiotic dosing and treatment failure in the obese population from the primary care perspective and accounts for BMI range, weight, comorbid diabetes, and tobacco use.
METHODS: This study was a retrospective chart review of 637 adult primary care patients designed to evaluate rates of treatment failure of outpatient cellulitis among patients of varying BMI. Treatment failure was defined as (a) hospital admission for intravenous antibiotics, (b) prolonged antibiotic course, or (c) requiring a different antibiotic after initial course.
RESULTS: Adverse outcomes were not statistically significant between normal BMI and those with BMI ≥40 kg/m(2). A subset of patients with a BMI ≥50 kg/m(2) was noted to have approximately twice the rate of adverse outcomes as the normal BMI group. While controlling for age, gender, race, diagnosis of diabetes mellitus, and tobacco use, a BMI of ≥50 kg/m(2) and a weight ≥120 kg was associated with adverse outcomes with an odds ratio of 2.440 (95% CI, 1.260-4.724; P = .008) and 2.246 (95% CI, 1.154-4.369; P = .017), respectively.
CONCLUSIONS: Patients with cellulitis weighing >120kg or with a BMI ≥50 kg/m(2) were at greatest risk for treatment failure in the outpatient setting, even when controlling for comorbid diabetes and tobacco use. As morbid obesity continues to become more prevalent, it becomes imperative that primary care physicians have better antibiotic dosing guidelines to account for the physiologic effects of obesity to minimize the risk of increased morbidity, health care costs, and antibiotic resistance.