Deep remission within 12 months prevents renal flare and damage accrual in lupus nephritis.

To evaluate the significance of achieving deep remission by induction therapy in lupus nephritis (LN) patients. We assessed consecutive patients undergoing induction therapy for active LN. Achievement of complete renal response (CR) was defined as a urine protein creatinine ratio (UPCR) ≤0.5 g/gCr, and deep remission (DR) was defined as a UPCR ≤0.15 g/gCr with stabilisation of serum creatinine levels assessed every 2-3 months. We compared renal flare and damage accrual rates among patients with CR, CR without DR, and DR at 3, 6, and 12 months and later. Fifty-nine Asian patients were enrolled, and the median observation period was 48.6 months. Of these, 55 patients achieved CR, and 33 achieved DR within 12 months of receiving induction therapy. The patients with DR within 12 months experienced a significantly lower rate of subsequent renal flare (p<0.001) and damage accrual (p=0.046) than those without CR, those with DR after 12 months, and those with no DR but CR within 12 months. In addition, younger age, shorter disease duration, lower urine protein at baseline, and earlier renal response were associated with DR within 12 months. Achievement of DR within 12 months after induction therapy should be a treatment target for active LN, as it has implications for preventing renal flare and damage accrual.