Background Given its immunomodulatory effects, hydroxychloroquine use is recommended in systemic lupus erythematosus (SLE). It is associated with a lower rate of appearance and of relapse of lupus nephritis (LN). LN is classically classified using ISN/RPS classification, but others indexes, such as the ones described by Austin and Hill, allow for the quantification of SLE activity in the kidney tissue.
Objectives To analyze the association between the use of hydroxychloroquine and the activity of LN in the kidney biopsy.
Methods Retrospective single center study of consecutive SLE and biopsy proven LN patients, diagnosed from 2010 to 2016. We evaluated the following outcomes: clinical remission, renal function and proteinuria at end of follow-up (g/24h). Complete remission was defined as a reduction of proteinuria to <0,5g/24h, inactive urinary sediment and serum creatinine <115% of baseline; partial remission same parameters, except proteinuria <1g/24h if initial value <3h/24h, or reduction to <3g/24h if initial value >3g/24h. Kidney biopsies were evaluated by the INS/RPS LN classification and the morphological indexes described by Austin and Hill, obtained after histomorphological review of renal biopsies. The studied predictor was the use of hydroxychloroquine. Statistical analysis was performed with STATA software, using one-way ANOVA, Qui2 and Pearson/Sperman test were appropriate.
Results During 6 years, there were 46 biopsy-proven LN cases, 84,8% (n=39) woman, median 35 years old (27–42,5) and 57,6% (n=19) caucasian. 39 patients were already known to have SLE, 7,44 (1,13–12,3) years previously. Of those 39 patients, 46% were under hydroxychloroquine and 77% under other immunosuppression.
The median follow-up was 31,9 (13,2–45,6) months. Based on biopsy findings, 35 patients were started on immunosuppression – induction in 50% of cases with MMF and in 50% with cyclophosphamide; maintenance in 81% with MMF, the rest with azathioprine. Complete remission was achieved in 58% of patients, 27% achieving partial remission. We observed 4 LN relapses. At the end of FUP, we saw a 96% (n=44) patient survival, with a median serum creatinine of 0,8 mg/dl (0,7–0,99), eGFR 99,8 ml/min (71,2–116,8) and proteinuria of 0,6 g/24h (0,2–1,6).
From those 46 patients, 30 were under immunosuppressive therapy at time of LN presentation, and 60% (n=18) were also under hydroxychloroquine. Table 1 summarizes the clinical findings:
With the use of hydroxychloroquine, we observed a lower histomorphological activity, as represented by a lower Hill biopsy index, and tendency towards lower Activity index. We also saw a tendency towards lower proteinuria.
Conclusions Our data reinforces the recommendations of using hydroxychloroquine for its adjuvant role in SLE patients, as we saw a lower histomorphological activity in kidney biopsy, and a trend towards lower proteinuria.
Disclosure of Interest None declared