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Abstract
Background Lupus nephritis (LN) affects up to 60% of patients with systemic lupus erythematosus. Complete renal response (CRR) at 12 months is recommended as a treatment target. Remission or low disease activity in extra-renal domains also contributes to one of the important treatment goals. This study evaluated the usefulness of Lupus Low Disease Activity State (LLDAS) as a treatment target in LN.
Methods Patients with a biopsy-proven active LN during the period of 2010–2020 were included. CRR was defined as proteinuria ≤0.5g/day (or equivalent) and normal estimate glomerular filtration rate (eGFR); partial renal response (PRR) was defined as a reduction of proteinuria by ≥50% with near-normal eGFR. The attainment of CRR, PRR, and LLDAS was evaluated at 12 months post-treatment. LN relapse was defined as worsening of proteinuria/serum creatinine and confirmed activity in repeat renal biopsy. The frequency of relapse was evaluated in patients who have achieved ≥50% proteinuria reduction to sub-nephrotic range post-treatment.
Results 143 LN patients were included with a median follow-up duration of 10.4 years. Most patients (74%) had class III/IV (±V) histological subtypes (table 1). At 12 months, 57(40%), 14(10%) and 69(48%) patients achieved CRR, PRR and LLDAS, respectively. Among 136 patients who achieved ≥50% proteinuria reduction to sub-nephrotic range, 30(22%) patients developed LN relapse after a median 2.98 years. CRR/PRR and LLDAS at 12 months were independent negative predictors of LN relapse. The risk of LN relapse was lowest among patients who achieved both LLDAS and CRR/PRR at 12 months (figure 1).
Conclusions LLDAS is an attainable target in LN and is associated with a lower risk of relapse. This study advocates the potential role of LLDAS as a complementary target to renal response in LN patients.
CRR=complete renal remission; LLDAS=lupus low disease activity state; NR=no response; PRR=partial renal response
C3=complement 3; C4=complement 4; CKD=chronic kidney disease; dsDNA=double stranded DNA; eGFR=estimated glomerular filtration rate; RNP=ribonucleoprotein; Sm=smith; UPCR=urinary protein-creatinine ratio; 24huP= 24-hour urine protein. eGFR calculated by MDRD formula
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