HLA-B27 negative reactive arthritis versus HLA-B27 positive reactive arthritis: A retrospective study.

Reactive arthritis (ReA) is defined as inflammatory arthritis secondary to an extra-articular infection with a key genetic background, HLA-B27. However, to date, the diagnosis and classification remain incomplete. The study focused on the similarities and differences in clinical manifestation, imaging features, and laboratory inspection between HLA-B27 negative patients and HLA-B27 positive patients in order to provide a reference for future development of diagnostic and classification criteria. Twenty-five ReA (19 HLA-B27 negative patients and 6 HLA-B27 positive patients) were included in this retrospective study. Clinical data, including demographics, clinical symptoms, imaging features, and laboratory inspection, were collected. The chi-square test and Mann-Whitney U test were used in the analysis. HLA-B27 negative group showed more involvement of upper extremities and small joints, while HLA-B27 positive group performed more axial symptoms. No significant difference was found in imaging features (ultrasound and magnetic resonance imaging) or laboratory inspection (microbes culture and infection-related indicators) between the 2 groups. ReA patients with different genetic backgrounds show various manifestations, although they encounter similar infections.