Background: Cellulitis is a common skin infection that classically presents with unilateral lower extremity erythema, swelling, and pain. The diagnosis is made clinically. Many conditions may mimic cellulitis that are collectively referred to as “pseudocellulitis.” These include stasis dermatitis, deep vein thrombosis, atopic dermatitis, psoriasis, and gout. The Alt-70 model is a validated clinical prediction tool for differentiating cellulitis from pseudocellulitis. It is unclear if it is utilized or if it has changed clinical practice in the emergency department setting.
Methods: This was a retrospective chart review study utilizing the HCA Healthcare Data Warehouse. The Alt-70 model was applied using electronic medical record data to characterize patients as having cellulitis or pseudocellulitis. The study included persons, ages 18-89, who were admitted to a North Texas division HCA hospital from the emergency department between January 2022 and December 2024 with a diagnosis of lower extremity cellulitis or lower extremity venous disorder.
Results: The final sample included 3,138 patients with a mean age of 54.9 years. The sample was 39% female. 254 (8.1%) patients had a diagnosis of a lower extremity venous disorder. 567 (18.07%) of patients had an ALT-70 score of 0-2, 1,560 (49.71%) patients had a score of 3-4, and 1,011 (32.22%) had a score greater than 4. The mean Alt-70 score was 3.59. There was no significant difference between Alt-70 score groups (“treat” vs “reassess” and “consultation” vs “reassess”) and prescription of inpatient antibiotics (p=0.96, p=0.26). There was no significant difference between Alt-70 score groups and hospital length of stay (p=0.60, p=0.06).
Conclusion: This study found no significant difference between the Alt-70 groups and antibiotic administration or hospital length of stay. These data suggest an overdiagnosis of cellulitis and an overuse of antibiotics. This study aligns with previous research indicating an overuse of medical resources, which may contribute to antibiotic resistance, nosocomial infections, hospital admissions, and other treatment-related adverse events. Utilization of the Alt-70 model with forced functions in electronic health systems, as well as education amongst hospital teams, may allow for better utilization of these diagnostic tools. Large prospective studies implementing this tool should be performed to understand its impact on the diagnosis and treatment of cellulitis and its imitators.

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