重症円形脱毛症に伴う爪異常に対するバリシチニブの有効性：48週間の単一施設後ろ向き研究

Alopecia areata (AA) is a chronic autoimmune disorder characterized by non-scarring hair loss, which may extend to total scalp (AA totalis) or whole-body hair loss (AA universalis). Nail involvement, though often underestimated, occurs in up to 66% of cases, especially in severe forms and in children.

This retrospective study evaluated the efficacy of baricitinib 4 mg/day, a Janus kinase 1/2 inhibitor, in treating nail manifestations associated with severe AA.

Thirty-seven patients with very severe AA (Severity of Alopecia Tool [SALT] score > 50) and nail involvement were treated with baricitinib for 48 weeks. Nail changes assessed included trachyonichia, pitting, leukonychia, and others. Clinical assessments were performed at baseline and at 12, 24, 36, and 48 weeks using the SALT score, onychoscopy, and the Clinician Reported Outcome (ClinRO) for nail appearance.

A significant improvement in both hair regrowth and nail abnormalities has been shown. The mean SALT score decreased from 100 to 16.3, and the average number of affected nails reduced from 6.4 to 2.1 (p < 0.001). ClinRO scores also significantly improved (p < 0.001). However, the correlation between hair and nail improvement was weak and not statistically significant (r = 0.15, p = 0.6). This suggests differential responsiveness of hair and nail units.

The findings support baricitinib as a promising treatment for nail involvement in AA, highlighting the need for routine nail assessment and development of more refined evaluation tools. Limitations include small sample size and lack of long-term data.