IgA rheumatoid factor is associated with bone mineral density preservation in rheumatoid arthritis.

INTRODUCTION: Autoantibodies such as IgM rheumatoid factor (RF) and anti-citrullinated proteins/peptides antibodies (ACPA) have previously been incriminated in systemic bone loss in rheumatoid arthritis (RA). There are, however, no data describing association of IgA RF and IgG RF with systemic bone loss. OBJECTIVE: This study was aimed to investigate the association of RF isotypes with systemic bone loss among patients with RA. METHODS: RF isotypes and ACPA were measured by enzyme-linked immunosorbent assay among 153 patients with RA. Bone mineral density (BMD) was assessed using dual-energy X-ray absorptiometry. RESULTS: Ninety-four (61.4%) patients had positive IgA RF, 89 (58.2%) had positive IgG RF, 109 (71.2%) had positive IgM RF, whereas 122 (80.3%) RA patients tested positive for ACPA. Compared to the IgA RF-negative patients, IgA RF-positive patients exhibited higher disease activity and had higher RF titers. Seven (4.6%) patients had low BMD at femoral neck, 12 (7.8%) at total femur, and 47 (30.7%) at lumbar spine. IgA RF was found to be associated with protection against low BMD at spine (OR = 0.47, 95% CI = 0.23-0.95, p = 0.034). This association was further confirmed in the multivariate regression analysis taking into account several potential confounding factors (OR = 0.21, 95% CI = 0.06-0.65, p = 0.039). No association between low BMD and the presence of IgG RF or IgM RF or ACPA was found. CONCLUSION: IgA RF for the first time ever was shown to be associated with BMD preservation at spine in RA. Key points • IgA RF was associated with protection against low spinal BMD. • No association between low BMD and the presence of IgG RF or IgM RF was found.

Ultrasound remission in patients with rheumatoid arthritis in clinical remission.

OBJECTIVES: The aim of the study was to assess ultrasound (US) remission in patients with rheumatoid arthritis (RA) in clinical remission using different definitions. MATERIAL AND METHODS: This was a cross-sectional study including patients with RA in clinical remission defined by disease activity score (DAS28)-erythrocyte rate (ESR) ≤ 2.6 for at least 6 months. Each patient underwent B-mode and power Doppler (PD) assessments of 42 joints and 20 tendons. B-mode and PD signal for synovitis and tenosynovitis (TS) were defined and graded semi-quantitatively (0-3) according to the outcome measures in rheumatology clinical trials (OMERACT). Several different definitions of US remission were examined: the absence of synovial hypertrophy (SH), TS on B-mode and PD signal, the absence of SH and PD signal, a grade ≤ 1 of SH and the absence of PD, a grade ≤ 1 of SH and PD, the absence of PD, or a grade of PD ≤ 1. The DAS28, clinical disease activity index (CDAI), simple disease activity index (SDAI), and the Boolean American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) remission criteria were compared. RESULTS: Thirty-seven patients were enrolled. The rate of remission according to the different composite indices was 70.2% for the SDAI, 64.8% for the CDAI, and 54% for the ACR/EULAR Boolean criteria. Synovial hypertrophy and TS in B-mode were detected in 94.6% and 40.5% of patients, respectively. Synovitis with PD signal was found in 59.5% and 13.5% of patients had TS with PD, respectively. Ultrasound remission at joints and tendons was found in 5.4-62.2% of patients. For the other remission criteria: CDAI, SDAI, and ACR/EULAR Boolean criteria, 7.7-60% of patients showed US remission at joints and tendons. CONCLUSIONS: Clinical remission, even classified by strict composite indices, does not seem to be the closest method to the concept of absence of inflammatory activity; hence the interest of integrating US in assessing remission in practice.