Impact of deep remission on renal flare in pure class V lupus nephritis: results from KEIO-SLE cohort, a retrospective cohort study.

OBJECTIVES

To clarify long-term prognosis and its relevant factors in patients with pure class V lupus nephritis (LN).

METHODS

We reviewed consecutive patients with biopsy-proven pure class V LN from KEIO-SLE cohort. The treatment target and deep remission (DR) were defined as urine protein-to-creatinine ratio <0.7 g/gCr and <0.15 g/gCr, respectively. Patients were divided into two groups based on the occurrence of renal flare, and baseline clinical and pathological characteristics were compared.

RESULTS

Thirty patients with pure class V LN were included. All patients achieved the treatment target. Among them, seven patients (23.3%) experienced renal flare. In the Firth's penalized Cox regression analysis, univariate analysis showed that smoking history, glucocorticoid monotherapy throughout follow-up, anti-ribonucleoprotein antibody positivity, Chronicity index ≥3, and non-achievement of DR were associated with an increased risk of renal flare. Multivariable analysis revealed that only non-achievement of DR remained an independent risk factor. Kaplan-Meier analyses showed significantly lower flare-free survival in patients with these risk factors. No patients developed end-stage kidney disease during a median observation period of 85.6 months.

CONCLUSION

Overall long-term prognosis of pure class V LN was favourable. However, approximately one-quarter of patients experienced renal flares. Failure to achieve DR, smoking history, throughout glucocorticoid monotherapy, and anti-ribonucleoprotein antibody positivity were associated with an increased risk of renal flare, with failure to achieve DR being the only independent risk factor.