Clinicopathological characteristics and prognosis of lupus nephritis patients with positive anti-ribonucleoprotein antibodies.

Background: Positive anti-ribonucleoprotein antibodies may characterize a subgroup of patients affected by lupus nephritis with mild kidney damage, but little is known about their clinical features and long-term prognosis.

Methods: Patients were retrospectively selected from the lupus nephritis database ( http://ln.medidata.cn ) of the First Affiliated Hospital of Sun Yat-sen University between 2006 and 2011. Logistic regression analysis identified the clinicopathological indicators related to positive anti-ribonucleoprotein antibodies. Additionally, the Cox proportional hazard regression model was used to assess the association of baseline variables with clinical outcomes.

Results: Of the 485 enrolled patients, 184 (37.9%) tested positive for anti-ribonucleoprotein antibodies. The group with positive anti-ribonucleoprotein antibodies exhibited a higher prevalence of rash, photosensitivity, and Raynaud's phenomenon, and lower scores on the systemic lupus erythematosus disease activity index (SLEDAI) and the Activity Index scores in kidney biopsies. It is important to note that, although proteinuria did not differ, patients with anti-ribonucleoprotein positivity had a lower prevalence of hematuria and cylindruria, and a higher estimated glomerular filtration rate than patients without anti-ribonucleoprotein antibodies. After a median follow-up of approximately 170 months, no significant differences were observed in kidney or patient survival between groups.

Conclusions: Lupus nephritis patients with anti-ribonucleoprotein antibodies present milder kidney damage and more dermatological manifestations. Despite the negative correlation between anti-ribonucleoprotein antibodies and both SLEDAI and activity index scores, these antibodies may not be predictive of better kidney outcomes.