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Current recommendations for the treatment of lupus nephritis (LN) suggest a goal-oriented treatment aimed at achieving the optimization of renal function and a proteinuria/creatininuria ratio between 500-700 mg/g at 12 months (complete clinical response). This level of proteinuria was found to have the greatest ability to predict a good long-term renal outcome in randomized clinical trials. The main objective of this study was to assess the long-term prognostic value of proteinuria after the first year of treatment in patients with LN, in a real-life retrospective cohort.
Patients diagnosed with systemic lupus erythematosus (SLE) (according to the SLICC 2012 and/or ACR/EULAR 2018 criteria) and treated at a University Hospital in Buenos Aires, who had a renal biopsy with LN between 2002 and 2017, and had at least 5 years of post-biopsy follow-up, were included. Renal biopsies and laboratory parameters at the time of the biopsy, at one year (12 +/- 4 months), and at five years of follow-up (60 +/- 4 months) were reviewed. Complete remission at one year was defined as a 24-hour proteinuria value (g/24h) or proteinuria/creatininuria ratio in an isolated sample (mg/g) ≤ 0.7 and a glomerular filtration rate measured by MDRD-4 (GFR) not greater than 20% from baseline. A good long-term renal response was defined as a creatinine value ≤ 1.0 mg/dl at 5 years of follow-up.
A total of 77 patients with renal biopsy were included (5 class II, 51 classes III/IV, 13 class V, and 8 combined), 87% were female, with an average age of 34.8 years (SD 12.4) at the time of the biopsy, and a post-biopsy follow-up time of 9.4 years (IQR 6.4 – 12.9). Most patients used Mophetil mycophenolate and cyclophosphamide as induction regimens (55.8 % and 31.1%, respectively). Mophetil mycophenolate was the most frequent drug used for maintenance therapy, accounting for 70% of the cohort. During follow-up, 6 patients (7.8%) required renal replacement therapy, with a median time to dialysis initiation post-biopsy of 2.5 years (IQR: 1.1 – 3.3), and 3 patients (3.9%) were transplanted within the follow-up period (Table 1). Renal parameters at baseline, one year, and five years are shown in Table 2. Complete remission at 12 months and 5 years was achieved in 58.7% and 68% of patients, respectively (Table 3). During this period, 23 patients (27.3%) required reinduction treatment, of which 17 (77.3%) achieved a good renal response at 5 years. During the follow-up, 7 patients had persistent isolated hematuria (without proteinuria), did not receive reinduction treatment, and had a good renal outcome at five years. The ROC curve analysis showed that proteinuria at one year could not predict good renal outcome at 5 years, with an area under the curve of 0.42 (0.25-0.59). The evaluation of combined parameters at 12 months (proteinuria ≤ 0.7 g/24 hrs + creatinine ≤ 1 mg/dl and red blood cells per field ≤ 5) found S: 42%, E: 70%, PPV: 89%, and NPV: 17% (Table 2).
In this cohort of patients with LN, proteinuria at one year showed no utility for predicting good long-term renal outcome at five years.
This abstract was also presented at the "56° Congreso Argentino de Reumatologia" in October 2023.