Long-term renal outcomes in multi-ethnic Southeast Asians with lupus nephritis: a retrospective cohort study.

BACKGROUND: Renal involvement is common among Asians with systemic lupus erythematosus and long-term renal outcomes have been described in homogeneous Caucasian and East Asian populations with lupus nephritis, but data are scarce for other ethnicities.

AIM: To evaluate the incidence and risk factors for progressive chronic kidney disease (CKD) in multi-ethnic Southeast Asians with lupus nephritis.

METHODS: This is a single-centre retrospective cohort study of adults with biopsy-proven lupus nephritis diagnosed between May 2001 and May 2009. Demographic and clinical data were retrieved from electronic medical records. Patients were excluded if baseline comorbid, renal function or pharmacotherapy data were incomplete or if they default follow-up within 3 months from time of diagnosis. Primary outcome was progressive CKD, defined by end-stage renal disease or persistent doubling of serum creatinine or reduction in eGFR ≥50% for ≥3 months from baseline.

RESULTS: We studied 113 patients with newly diagnosed biopsy-proven lupus nephritis. Median age was 42 (interquartile range 29-52) years; the majority were Chinese (76%; Malay 13% and others 11%) and female (81%). Two-thirds had International Society of Nephrology and Renal Pathology Society Class III or IV nephritis; serum creatinine was 86 (67-125) μmol/L with heavy proteinuria (6.3 (2.5-12.2) g/g creatinine). Median follow-up was 110 (83-142) months. Remission (partial and complete) occurred in 96% at 3.1 (1.6-5.2) months after diagnosis. Among patients who achieved remission, 56% had disease relapse at 19.0 (6.0-40.2) months after remission. Patients with progressive CKD (n = 13, 11%) had lower baseline CKD Epidemiology Collaboration estimated glomerular filtration rate (37.3 (16.5-82.0) vs 79.4 (57.5-101.0) mL/min/1.73 m2 , P = 0.03) and higher chronicity index (5 (3-6) vs 3 (2-3), P = 0.04) than those who did not. Remission, early remission within 6 months, complete remission and non-relapse were less frequently associated with progressive CKD (P < 0.01).

CONCLUSION: Multi-ethnic Southeast Asians with biopsy-proven lupus nephritis had high remission rates and low incidence of progressive CKD. Progressive CKD was associated with poorer baseline renal function, higher histological chronicity index, failure to achieve remission and occurrence of relapse.