[Clinical characteristics and outcomes of children with rheu-matoid factor-positive polyarticular juvenile idiopathic arthritis].

Abstract

Objectives: To compare the clinical characteristics and outcomes between patients with rheumatoid factor (RF)-positive and RF-negative polyarticular juvenile idiopathic arthritis (pJIA).

Methods: A retrospective analysis was conducted on clinical data of 131 children diagnosed with pJIA at the Children's Hospital, Zhejiang University School of Medicine from January 2019 to January 2025. Patients were divided into an RF-positive group (n=59) and an RF-negative group (n=72) based on serum RF status. Disease activity was assessed using the Juvenile Arthritis Disease Activity Score-27 (JADAS-27). All patients were followed for at least 6 months, with a maximum follow-up duration of 6 years. Clinical features, laboratory findings, and outcomes were compared between the two groups.

Results: Among the 131 pJIA patients, 122 (93.1%) had high disease activity at baseline. Compared with the RF-negative group, the RF-positive group had a higher proportion of females (58.3% vs. 84.7%, P<0.01), an older age at onset (7.14±3.98 years vs. 8.86±4.02 years, P<0.05), and a higher prevalence of interstitial lung disease (4.2% vs. 23.7%, P<0.01). The most frequently affected joints were the wrist in the RF-positive group, and the knee joints in the RF-negative group. At baseline, serum levels of IL-2, IL-6, IL-10, and tumor necrosis factor-α were significantly higher in the RF-positive group than those in the RF-negative group (all P<0.05). A total of 101 patients (77.1%) received biologic-targeted therapies, 46 (78.0%) in RF-positive group, and 55 (76.4%) in RF-negative group. Among them, 23 RF-positive patients (50.0%) and 12 RF-negative patients (21.8%) required two or more biologic-targeted drugs. RF positivity was identified as an independent risk factor for the use of two or more biologic-targeted drugs (OR=3.232, 95%CI: 1.109-9.421, P<0.05). Both groups showed significant reductions in JADAS-27 scores at 3, 6, 12, 24, 36, 48, 60, 72 months after treatment initiation compared with baseline (all P<0.01), with no significant differences in JADAS-27 scores or remission rates between the two groups at any follow-up time point (all P>0.05). The median time to achieve first clinical remission after treatment was 24 months in both groups (P>0.05). No significant differences were observed in remission rates or the proportion of patients requiring two or more biologic-targeted drugs among different types of biologic-targeted drugs (all P>0.05).

Conclusions: Children with RF-positive pJIA showed higher baseline inflammatory status and a higher incidence of pulmonary involvement, yet they achieved comparable remission rates to those with RF-negative pJIA. Biologic-targeted therapies may contribute to improved remission rates and outcomes, but RF-positive patients may require switching or combination therapy with different targets to achieve clinical remission.