A Predictive Model of Recurrent Lower Extremity Cellulitis in a Population-Based Cohort

Abstract

Background: Cellulitis is common and recurs in some patients. The study described herein derived a predictive model for the recurrence of lower extremity cellulitis in a population-based cohort. Methods: We conducted a retrospective, populationbased cohort study using the Rochester Epidemiology Project. We reviewed the medical records of Olmsted County, Minnesota, residents with lower extremity cellulitis occurring from January 1, 1999, to June 30, 2000. Univariate and multivariate Cox proportional hazards analyses were performed to evaluate risk factors in patients who experienced recurrent lower extremity cellulitis within 2 years. A predictive model was developed to estimate risk of recurrence based on a score of risk factors identified by multivariate analysis. Results: A total of 209 episodes met the definition of lower extremity cellulitis. Thirty-five patients (16.7%) experienced recurrence within 2 years. Multivariate analysis identified tibial area involvement, prior malignancy, and dermatitis affecting the ipsilateral limb as independent risk factors for recurrence, with hazard ratios of 5.02, 3.87, and 2.99 (PϽ.01), respectively. A score calculated from these variables (a count of 0, 1, 2, or 3) was developed to measure risk of recurrence. Based on the predictive model, the estimated probability of recurrence (95% confidence interval [CI]) within 2 years was 5.0% (95% CI, 1.6%-8.2%), 17.3% (95% CI, 11.1%-23.0%), 50.6% (95% CI, 34.2%-63.0%), or 92.8% (95% CI, 51.9%-98.9%) for a score of 0, 1, 2 or 3, respectively. Conclusions: We derived a model including tibial area involvement, history of cancer, and dermatitis to predict recurrence of lower extremity cellulitis. Potential interventions can be incorporated into treatment to diminish the proclivity for recurrence in high-risk patients.

Streptococcal Cellulitis/Erysipelas of the Lower Leg

“…This prevalence compares with a prevalence of 66% in 167 patients with cellulitis who were examined by dermatologists [16]. Tinea pedis did not have significance as a risk factor for recurrence in a predictive model based on 209 episodes with 35 recurrences [61]. In a study of antibiotic prophylaxis discussed above [65], the 50% recurrence rate in the control group occurred despite treatments for tinea pedis.…”

“…In 209 episodes of leg cellulitis, 35 patients (16.7%) had recurrences within 2 years [61]; possible predictive factors for recurrence were evaluated, and tibial area involvement, prior malignancy, and dermatitis of the ipsilateral limb were all independent risk factors for recurrence on multivariate analysis, with hazard ratios (HRs) of 5.02, 3.87, and 2.9, respectively. If all three were present, the estimated probability of recurrence was 92.8% (95% CI, 51.9-98.9%).…”

“…It is uncertain why previous malignancy predisposes to recurrences [61]. Lymphatic obstruction caused by tumors is a plausible explanation [24].…”

“…Lymphatic obstruction caused by tumors is a plausible explanation [24]. It is also uncertain why involvement of the tibial area is linked with a risk of recurrence [61], although involvement of the tibia may have been a surrogate for severity, as the reference comparator was involvement of the foot.…”

Reply to: “A potential underestimation of the number of cellulitis recurrences in study”

“…Furthermore, the recurrence rate of cellulitis was 45.3% at 1 year, which is higher than that reported in other studies. 8,9 This may be reflective of an inpatient cohort characterized by older age, more severe disease, increased comorbidities, and comprehensive data collection. We do not think that the rate of recurrence is underestimated.…”