Objective Lupus nephritis (LN) is one of the most severe organ manifestations in SLE. The aim of our study was to determine the incidence of LN and to compare the clinical characteristics, survival rate and outcome of SLE patients with and without LN. We also compared the data of patients diagnosed with LN before and after 2005.

Methods The patients were followed up between 1990 and 2020 at the Dept. of Clinical Immunology, Faculty of Medicine, University of Debrecen. We recorded the clinical and laboratory findings of the patients, as well as their immunosuppressive treatments.

Results Of 384 SLE patients, 127 had LN (33.07%). The age at the onset of SLE was significantly lower in patients with LN (p<0.001). Discoid lupus erythematosus (p<0.001) and subacute cutan lupus erythematosus (p=0.01) occurred more often in SLE patients without LN. Rheumatoid arthritis (p=0.009), antiphospholipid(p=0.044) and Sjögren’s syndrome (p=0.017) were also more common in patients without LN. Anaemia (p<0.001) and anti-RNP positivity (p=0.049) were more common in patients with LN. Antimalarials (p=0.004) and methotrexate (p=0.001) were used more often in patients without LN, while rituximab (p<0.001), cyclophosphamide (p<0.001) and MMF (p<0.001) were more commonly used in LN group. LN did not significantly worsen the survival in SLE patients. Male gender was a negative prognostic factor in patients without LN. Remission status was a positive prognostic factor in patients with and without LN, but low disease activity significantly improved survival only in patients with LN. Sepsis-related mortality was higher in the LN group (p=0.031). The prevalence of serositis (p=0.007) and neurological manifestations of SLE (p=0.001) were decreased in patients with LN diagnosed after 2005. After 2005, the use of mycophenolate mofetil therapy increased (p<0.001). The use of cyclophsophamide and the cumulative steroid doses also decreased after 2005. The SLICC damage index score decreased after 2005 as well (p=0.001).

Conclusion Lupus nephritis did not influence disease outcome in our SLE patients. Low disease activity status significantly improves survival in LN but not in SLE patients without LN. The main therapeutic goal is to achieve remission in SLE patients with or without LN.