Renal vascular lesions in childhood-onset lupus nephritis

Background This study aimed to determine the clinical significance of renal vascular lesions (RVLs) in childhood-onset lupus nephritis (cLN). Methods We retrospectively reviewed all children with biopsy-proven cLN between 2004–2020 to evaluate the prevalence of RVLs on kidney biopsy and its associated factors and long-term outcomes. The composite kidney outcome was defined as advanced chronic kidney disease (CKD) stage 3–5, kidney failure and death. Results 107 biopsies from 84 Chinese patients were analysed. RVLs were observed in 19 patients (22.6%), including non-inflammatory necrotizing vasculopathy (NNV, n = 6), thrombotic microangiopathy (TMA, n = 4), arterial sclerosis (AS, n = 3), concurrent NNV with AS ( n = 4), concurrent NNV with TMA ( n = 1) and concurrent true renal vasculitis with AS ( n = 1). The presence of RVLs was associated with lower estimated glomerular filtration rate (eGFR) (66.9 ± 40.3 vs. 95.6 ± 39.4 ml/min/1.73m 2 , p = 0.005), haemoglobin level (9.1 ± 1.9 vs. 10.4 ± 1.9 g/dL, p = 0.008) and platelet count (150.1 ± 96.4 vs. 217.2 ± 104.8 × 10 9 /L, p = 0.01). LN classes and activity/chronicity indices were similar. Patients with RVLs had poorer composite kidney outcomes, though not reaching statistical significance (log-rank test, p = 0.06). The presence of NNV was associated with inferior survival free from composite kidney outcome (log-rank test, p = 0.0018), compared to other forms of RVLs and those without RVLs. Univariate analysis revealed NNV (HR 7.08, 95% CI 1.67–30.03) was predictive of composite kidney outcome. Conclusion RVLs are present in one-fifth of cLN patients and are associated with severe presentation. NNV is associated with worse long-term kidney outcome. Routine evaluation of RVLs is warranted and should be incorporated into future classification criteria. Graphical Abstract A higher resolution version of the Graphical abstract is available as Supplementary information