The Clinical Significance Of Rheumatoid Factor In Antineutrophil Cytoplasmic Antibody-associated Vasculitis

Objective This study aimed to investigate the role and clinical significance of rheumatoid factor(RF)in antineutrophil cytoplasmic antibody(ANCA)-associated vasculitis(AAV)patients.Methods The clinical data of 94 patients with AAV were retrospectively analyzed.AAV Patients and its phenotypes was divided into two groups based on RF positivity: RF-positive group(RF ≥ 12.5U/ml)and RF-negative group(RF < 12.5U/ml).The clinical manifestations,laboratory tests,renal pathology,treatment and outcomes of the two groups of AAV patients were compared.Results RF was positive in 53(56.4%)AAV patients,median age:57 years,(IQR50-68),female:59(62.8%),males 35(37.2%),median disease duration:60days).The age and the level of high-sensitivity C-reactive protein(hs-CRP)were higher in the RF-positive group AAV patients than RF-negative group AAV patients(63 vs.55year,p=0.029;92 vs.24mg/l,p<0.001;respectively).And the serum creatinine(SCr)and 24-hour proteinuria were lower in the RF-positive group AAV patients(1.8mg/dl vs.3.6mg/dl,p=0.022;0.4g/24h vs.0.9g/24h,p=0.015;respectively).RF titers showed significant correlations with the levels of hs-CRP,SCr,proteinuria,and estimated glomerular filtration rate(eGFR)(r=0.478,p<0.001;and r=-0.296,p=0.004;and r=-0.333,p=0.001;and r=0.244,p=0.018;respectively).Even after adjusting for age,RF titer was still significantly correlated with hs-CRP,proteinuria,and eGFR(r=-0.385,P<0.001;r=-0.239,P=0.021;r=0.308,P=0.003;respectively.There were no significant differences in clinical manifestations,BVAS,ANCA type,hemoglobin,complement,erythrocyte sedimentation rate(ESR),renal histopathological categories,renal complement/immunoglobulin deposition between the two groups.Multivariate logistic analysis showed that RF positivity was not an independent risk factor for renal involvement.RF positivity did not affect the induction therapy,initiation of dialysis,PLEX,or usage of mechanical ventilation in AAV patients.The patient survival,death-censored renal survival,and relapse-free survival showed not statistically difference among RF(+)and RF(-)AAV patients.Conclusion(1)RF-positive AAV patients showed higher age and higher level of hs-CRP,and lower SCr.and lower 24-hour proteinuria than RF-negative AAV patients.(2)RF titers showed significant correlations with the levels of hs-CRP,proteinuria,and eGFR.Multivariate logistic analysis showed that RF positivity was not an independent risk factor for renal involvement.(3)RF positivity did not affect the renal complement,treatment,and outcome in AAV patients.(4)RF-positive AAV patients did not overlap with RA at onset,developed RA during long-term follow-up.