Background Lupus nephritis (LN) is relapsing remitting disease. The standard regimen for LN treatment comprises of induction and maintenance phases.

Aims To study the incidence of LN flare in patients who had renal complete remission (CR) after receiving standard regimens for LN, time from renal remission to flare and to identify factors associated with renal flare after CR in clinical practice.

Methods We observed the clinical outcomes of patients who had 1^st LN episode and achieved CR (24 hour urine protein <0.5 gm/day with normal renal function), within 12 months after receiving induction phase, and received the maintenance phase for at least 18 months. Demographic characteristics, clinical, laboratories and treatments variable, every 3 months from the time of CR to flare or to last follow-up were recorded.

Results Among 548 patients who were currently follow-up, 171 patients had 1^st LN episode. Of these, 87 patients (96.6% female with mean age 29.5±10.8 years) met the inclusion criteria. During 6.1±3.4 years of observation, the incident of LN flare was 48.3%. The mean time from CR to flare was 3.14 years (min 0.5, max 9.5). Logistic regression analysis revealed remaining dose of prednisololne ≥7.5 mg/day after remission reduced incidence of renal flare (Odd ratio 0.26 (95%CI 0.08–0.85), p=0.025), while demographic characteristics, clinical variables, and other treatments variables were not associated with incidence of LN flare.

Conclusions Although achieving CR with standard treatment, almost half of patients had LN flare within a few years. This study emphasise that maintenance phase in LN is crucial.