Track: Clinical Studies

Abstract:

Epidermolysis bullosa acquisita (EBA), a rare subepidermal blistering disorder characterized by autoantibodies against collagen VII (ColVII), can lead to mucocutaneous blistering. Accurate diagnostic assays are critical for diagnosis and for informing appropriate treatment and multidisciplinary clinical evaluation¹. Currently available assays for circulating collagen VII autoantibodies include IIF with ColVII-transfected cells (IIF-T) and ELISA, though both may be limited by low circulating autoantibody titers and/or specificity challenges^{2, 3}^,⁴. This pilot study compares the performance of IIF-T to ELISA for the diagnosis of EBA. We identified patients with known positive ColVII ELISA or IIF results (2010-2025). Thirteen patients (14 serum samples) were identified, of whom 4 (30.7%) had confirmed EBA. Using confirmed clinical diagnosis of EBA as the gold-standard, sensitivity, specificity, negative-predictive value, and positive-predictive value for ELISA were 75%, 10%, 50%, and 25%, respectively, while those for IIF-T were 100%, 80%, 100%, and 67%, respectively. In summary, this pilot study demonstrates IIF with ColVII-transfected cells has a higher sensitivity and specificity compared to ELISA for EBA, in keeping with results of prior studies⁵. Limitations include sample size, retrospective design, and inclusion of only positive serum samples. It is plausible that patients with diagnoses other than EBA may have true circulating ColVII antibodies as a result of epitope spreading. Future investigations with an expanded patient panel could assess the incremental value of using both assays in the diagnosis of EBA, and the utility of ColVII testing in bullous systemic lupus, another condition mediated by ColVII antibodies.

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Anatilde Gonzalez Guerrico