Risk of intestinal involvement in mucocutaneous-onset Behçet's disease: data from the AIDA network registry

Objective: Behçet's disease (BD) may initially manifest solely with mucocutaneous involvement. This study aimed to identify demographic and clinical factors associated with subsequent intestinal involvement in patients presenting exclusively with mucocutaneous manifestations during early disease stages. Methods: Data were obtained from the International AutoInflammatory Disease Alliance Network registry dedicated to BD; a Bayesian statistical approach was employed to address the limited sample size resulting from subgroup stratifications. Results: In total, 328 BD patients with exclusively mucocutaneous onset were enrolled; of these, 46 (14%) developed intestinal involvement over time. The risk of ocular involvement was higher among patients with intestinal manifestations (OR: 3.02, 95% CrI: 1.24-6.08; posterior probability: 99.3%). Minor aphthous ulcers without major aphthosis were protective towards intestinal involvement (OR: 0.47, 95% CrI: 0.22-0.98; posterior probability: 97.98%). Conversely, major aphthous ulcers increased the risk (OR: 3.25, 95% CrI: 1.50-7.02; posterior probability: 99.7%), along with the combination of oral major aphthosis with: i) genital aphthosis (OR = 2.77, 95%CrI: 1.14-6.58; posterior probability: 98.45%); ii) pseudofolliculitis (OR = 3.18, 95%CrI: 1.15-8.33; posterior probability: 98.72%); iii) genital aphthosis plus pseudofolliculitis (OR = 5.22, 95%CrI: 1.71-16.35; posterior probability of 99.77%). Pseudofolliculitis plus cutaneous manifestations other than erythema nodosum were protective against intestinal involvement (OR = 0.01, 95%CrI: 0.0-0.98; posterior probability: 97.55%). Conclusion: Major aphthosis was the strongest factor associated with intestinal involvement in BD patients initially presenting with mucocutaneous symptoms only. In such patients, intestinal involvement correlated with increased risk of ocular inflammation.