Per-protocol Repeat Kidney Biopsy in Incident Cases of Lupus Nephritis

Lupus nephritis (LN) is one of the most severe complications of systemic lupus erythematosus (SLE). Among people living with SLE, 35-60% will develop LN during the course of the disease. This complication is one of the factors that contribute to deterioration of the renal function. Some centres perform kidney biopsies after completion of treatment for an episode of LN as a part of the treatment evaluation. The term "repeat biopsy" is often used to describe these biopsies. Several studies have reported that repeat kidney biopsies show activity at the level of tissue, even in patients with normal routine blood and urine markers. The investigators strongly believe that this information is important, and should be taken into consideration during decision of treatment. To provide evidence for this, the investigators have designed a collaborative project within the frame of the Lupus Nephritis Trials Network. With this research project, the investigators want to contribute to an increased proportion of patients with LN who achieve remission (inactivity) of LN, and a reduced proportion of patients who worsen in renal function in the long term. Patients with SLE who develop a first episode of LN will be asked to participate in this project, and will receive treatment according to current guidelines. Half of the patients will undergo a repeat biopsy 12 months later, and half of the patients will not. The selection of patients who will undergo or not undergo repeat biopsy will be random. Patients with high disease activity at the level of kidney tissue will receive more intense immunosuppressive treatment. Patients who have not undergone repeat biopsy will continue to be treated according to standard routine. The investigators will compare the results of treatment between the group of patients who underwent and the group of patients who did not undergo repeat biopsy, with regard to (i) complete disease inactivity at month 24 and (ii) renal function at month 60 from treatment initiation. The investigators expect that significantly greater proportions of patients in the repeat biopsy group will have inactive disease at month 24 and adequate levels of renal function at month 60. This will provide support for performing repeat biopsies as a part of the treatment evaluation, in order to optimise the therapeutic management and improve the long-term prognosis of patients with LN.