Lower-Extremity Cellulitis Diagnosed With Increased Accuracy Using ALT-70 Predictive Model vs Thermal Imaging

The ALT-70 predictive model outperforms thermal imaging in the diagnosis of lower-extremity cellulitis, according to the results of a single-center, prospective, head-to-head comparison of the 2 methods. Findings were published in the Journal of the American Academy of Dermatology.

The investigators of the current analysis collected ALT-70 and thermal imaging data from patients with presumed lower-extremity cellulitis, with the objective being to compare the classification measures and the accuracy of ALT-70, thermal imaging, and combination testing with ALT-70 plus thermal imaging.

A total of 67 patients with presumed lower-extremity cellulitis, ALT-70 scores, and thermal imaging data were enrolled in the study. The mean age of the participants was 59.0 ± 19.3 years (range, 18 to 97 years). 

The gender distribution was approximately equal, with 52.2% of the participants being women. Overall, 79.1% of the patients enrolled were white. All 67 patients were examined by a board-certified dermatologist (which is considered the gold standard), who provided a clinical diagnosis of cellulitis (n=46) or pseudocellulitis (n-21) based on clinical impression. Data collection took place between February and September 2017.

ALT-70 conferred the highest sensitivity (97.8%) and negative predictive value (90.9%), whereas combination testing yielded the highest specificity (71.4%) and positive predictive value (86.6%). Compared with thermal imaging, the use of ALT-70 was associated with improved classification measures. The use of combination testing conferred a marginal benefit over the use of ALT-70 alone.

The investigators concluded that the accuracy of ALT-70 was high and consistent with that stated in prior published reports. The widespread implementation of ALT-70 into clinical practice may help decrease misdiagnosis rates of lower-extremity cellulitis. Additional studies are warranted to validate the generalizability of the study results in a larger patient cohort, with the single-center design being a major limitation.

Reference

Li DG, Dewan AK, Di Xia F, Khosravi H, Joyce C, Mostaghimi A. The ALT-70 predictive model outperforms thermal imaging for the diagnosis of lower extremity cellulitis: a prospective evaluation [published online July 9, 2018]. J Am Acad Dermatol. doi: 10.1016/j.jaad.2018.06.062