Assessment of Bullous Pemphigoid Disease Area Index during Treatment: A Prospective Study of 30 Patients

<b><i>Background:</i></b> Recently, a consensus Bullous Pemphigoid Disease Area Index (BPDAI) was proposed to measure therapeutic outcomes in bullous pemphigoid (BP). <b><i>Objective:</i></b> To compare BPDAI with other clinical parameters of disease activity at baseline and to describe the variations of BPDAI during the initial phase of treatment. <b><i>Methods:</i></b> Thirty BP patients were included and followed for 1 year. BPDAI was assessed at baseline and on days 30, 90 and 360 by the same investigator. Concomitantly, the number of daily new blisters, the skin surface area of erythematous/eczematous/urticarial plaques and blisters/erosions, total lesion area (TLA), pruritus score and mucosal involvement were recorded. <b><i>Results:</i></b> At baseline, BPDAI was 46.7 ± 25 (mean ± SD); it was well correlated with erythematous/eczematous/urticarial skin surface (r = 0.63), TLA (r = 0.83), number of daily new blisters (r = 0.7; p ≤ 0.0002) and anti-BP180 autoantibodies (r = 0.49; p = 0.006), but not with anti-BP230 autoantibodies. For the 8 patients with severe BP at baseline, the mean BPDAI was 76.5, versus 35.9 for moderate BP (p = 0.0007). A value of 56 was proposed as a cut-off value for severe BP. BPDAI decreased to 11.9 ± 8.7, 10.7 ± 12.7 and 2.5 ± 4.1 on days 30, 90 and 360, respectively. <b><i>Conclusion:</i></b> BPDAI rapidly decreased during the early treatment stage of BP with variations almost totally conditioned by the skin activity component.