CKD in Lupus Nephritis: Prevalence and Risk Factors in a Single-Centre Chinese Cohort

Background: Despite treatment advances, 10-20% of patients with lupus nephritis (LN) progress to end stage kidney disease (ESKD). Understanding the burden and risk factors of developing chronic kidney disease (CKD) is pivotal in preventing ESKD. We aim to study the prevalence of CKD, defined as estimated glomerular filtration rate (eGFR) <60ml/min/m2, its evolution over time, and associated risk factors. Methods: Patients with an incident episode of biopsy-proven LN diagnosed from January 1981 to December 2014 were included, with follow-up censor date February 15 2017. Patients with <2 years of follow-up were excluded. Data were obtained from retrospective review of medical records. Results: 149 patients with a mean follow up of 15.8±8.5 years were studied; 90% were female and 70.5% had Class III/IV±V LN. Remission (partial or complete) occurred in 83.9% of patients; 56.4% had disease relapse at a median of 3.73 (0.5-27) years after remission. 29.5% developed CKD and 7.4% progressed to ESKD during the study period. Older age, presence of hypertension, an eGFR of <60ml/min, lower C3 and higher dsDNA levels at time of incident biopsy were risk factors for CKD. 24.8% of patients had an eGFR of <60ml/min at the time of incident biopsy, and kidney function improved in over half after treatment, with percentages decreased to 11.7% and 10.7% at 6 months and 1 year respectively. The percentage with eGFR of <60ml/min then increased to 14.1% at 2 years and 14.5% at 5 years. Non-response to treatment, a higher number of flares (2.2±2 vs 1±1.3, p<0.01) and having ≥2 flares were associated with incident CKD during follow-up. Use of mycophenolate mofetil as induction therapy (and continued as maintenance treatment) was associated with reduced risk of CKD development (adjusted OR 0.18, p=0.01). Calcineurin inhibitor use did not differ significantly between those who had or had not developed CKD during follow up (34.1% vs 21.9%, p=0.12). Renin-angiotensin blockers were more commonly used in those with CKD (81.8% vs 61.9%, p=0.02). Conclusion: CKD is common in patients with LN. Renal impairment at LN flare often improves with treatment, but CKD progresses over time. Efforts to prevent ESKD should focus on modifiable risk factors including optimizing immunosuppressive treatment, prevention of flares, and renoprotective measures.