A predictive model of recurrent lower extremity cellulitis in a population-based cohort

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, population-based 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 (P<.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 [Cl]) 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.