Patient characteristics
A total of 101 pediatric patients who were newly diagnosed with SLE were identified during the study period, and their demographics are shown in (Table 1). There were 85 females and 16 males, with a sex ratio of 84:16. The mean age at the onset of SLE was 10.76 ± 2.35 years, while the mean time from onset to diagnosis was 61.74 ± 97.51 days. Thirteen (12.9%), 17 (16.8%), and 71 (70.3%) patients had an SLEDAI-2K score of ≤ 6, 7–12, and > 12, respectively. The antinuclear antibody (ANA) level was 1:100, 1:320, 1:1000, and 1:3200 in 8 (7.9%), 16 (15.8%), 42 (41.6%), and 35 (34.7%) patients, respectively. We also examined the complement levels and found that the mean C3 level was 0.49 ± 0.38, while the mean C4 level was 0.08 ± 0.07. The proportion of patients who were positive for anti-double-strand DNA antibody (anti-dsDNA Ab), anti-Smith antibody (anti-Sm Ab), anti-centromere proteins antibody (anti-CENP Ab), anti-proliferating cell nuclear antigen antibody (anti-PCNA Ab), anti-nucleosome antibody (anti-NU Ab), anti-histone antibody (anti-HI Ab), anti-ribosomal-P antibody (anti-Rib-P Ab), anti-mitochondrial antibody-M2 (AMA-M2), anti-U1 small nuclear ribonucleoprotein antibody (anti-U1RNP Ab), anti-Sjogren’s syndrome A antibody (anti-SSA Ab), anti-Sjogren’s syndrome B antibody (anti-SSB Ab), anti-scleroderma-70 antibody (anti-Scl70 Ab), anti-polymyositis-sclerosis antibody (anti-PM Scl Ab), anti-neutrophil cytoplasmic antibodies (ANCA), lupus anticoagulant (LAC), anti-cardiolipin antibodies (aCL Abs), and anti-beta2-glycoprotein I antibodies (β2GPI Abs) were 61.4%, 32.7%, 3.0%, 2.0%, 59.4%, 51.5%, 29.7%, 28.7%, 41.6%, 38.6%, 20.8%, 4.0%, 12.9%, 46.5%, 32.7%, 21.8%, and 23.8%, respectively. We also evaluated the involvement of organs and systems in children with lupus at the time of diagnosis. There were 57.4% of children with a skin rash, 52.5% had a fever, and 4.0% had MAS. Among children with lupus, 73.3% had a renal disorder, 71.3% had a hematologic disorder, 14.9% had arthritis, 19.8% had a pulmonary disorder, 12.9% had a cardiac disorder, 30.7% had a digestive disorder, 35.6% had hypothyroidism, and 22.8% had a neurologic disorder. The raw data are shown in (Supplementary Table 1)
Clinical Features of NPSLE
Among the 101 children with SLE, 23 had NPSLE. Most children with NPSLE had a headache (34.8%), a mood disorder (26.1%), or an autonomic disorder (26.1%), and several had cerebrovascular disease (17.4%), movement disorders (13.0%), cognitive dysfunction (8.7%), seizure disorders (4.3%), and an acute confusional state (4.3%). Radiological examination revealed that 95.6% of them had abnormal brain magnetic resonance imaging results, and 17.4% had an abnormal electroencephalogram (Table 1).
NPSLE occurred in 23 (22.8%) children with SLE, aged 11.1 ± 2.02 years at diagnosis. Among those with NPSLE, 91.3% were females, whereas female patients accounted for 82.1% of those without NPSLE (P = 0.352).
When children with SLE alone were compared with those with NPSLE (Table 2), children with NPSLE were more likely to have a fever (44.9% vs. 78.3%, P = 0.01), a higher SLEDAI-2K score (14.46 ± 7.26 vs. 23.57 ± 6.77, P < 0.001), higher ANA levels (P = 0.025), and lower C4 levels (0.08 ± 0.08 vs. 0.05 ± 0.05, P = 0.041) than those of children with SLE alone. Anti-Rib-P Ab, AMA-M2, and ANCA were more frequently positive in children with NPSLE than in children with SLE alone (21.8% vs. 56.5%, P = 0.003; 23.1% vs. 47.8%, P = 0.041; and 39.7% vs. 69.6%, P = 0.022; respectively). For antiphospholipid antibody, the LAC and β2GPI Abs were more frequently positive in children with NPSLE than in those with SLE alone (24.4% vs. 60.9%, P = 0.002, and 17.9% vs. 43.5%, P = 0.025, respectively). Regarding organ and system involvement, children with NPSLE were more prone to digestive disorders (23.1% vs. 56.5%, P = 0.005), MAS (0 vs. 17.4%, P = 0.002), and hypothyroidism (29.5% vs. 56.5%, P = 0.033) than those with SLE alone (Table 2).
Risk Factors for NPSLE
We sought to identify associations between clinical or laboratory data and neurologic involvement at SLE diagnosis. In univariate logistic regression analyses, the presence of anti-Rib-P Ab (OR = 4.665, 95% CI 1.743–12.481; P = 0.002), anti-SSA Ab (OR = 3.168, 95% CI 1.197–8.384; P = 0.02), AMA-M2 (OR = 3.056, 95% CI 1.155–8.085; P = 0.024), anti-PM Scl Ab (OR = 3.58, 95% CI 1.065–12.03; P = 0.039), ANCA (OR = 3.465, 95% CI 1.278–9.394; P = 0.015), β2GPI Ab (OR = 3.516, 95% CI 1.285–9.626; P = 0.014), aCL Ab (OR = 5.231, 95% CI 1.815–15.074; P = 0.002), or LAC (OR = 4.83, 95% CI 1.805–12.924; P = 0.002) was a significant risk factor for NPSLE. Children with positive ANA (OR = 1.005, 95% CI 1.001–1.111; P = 0.003) and a high SLEDAI-2K score (OR = 1.204, 95% CI 1.101–1.318; P < 0.001) were also more likely to develop NPSLE. Fever (OR = 4.423, 95% CI 1.492–13.111; P = 0.007), digestive disorders (OR = 4.333, 95% CI 1.629–11.526; P = 0.003), and hypothyroidism (OR = 3.109, 95% CI 1.193–8.097; P = 0.02) were also risk factors for NPSLE in children with lupus. In contrast, high serum complement (C3 and C4) levels were protective against NPSLE (C3: OR = 0.503, 95% CI 0.118–0.938; P = 0.035 and C4: OR = 0.024, 95% CI 0.009–0.982; P = 0.035) (Table 3).
We performed multivariate analyses for the factors that were significantly different in the univariate analysis. This showed that a high SLEDAI-2K score (OR = 1.215, 95% CI 1.019–1.449; P = 0.03), the presence of β2GPI Ab (OR = 4.603, 95% CI 1.834–25.412; P = 0.04), and the presence of anti-Rib-P Ab (OR = 4.153, 95% CI 1.865–19.95; P = 0.038) were significantly associated with NPSLE (Table 4). The forest map was drawn for the results of multi-factor logistics regression analysis, and the OR value and its 95% confidence interval were visualized (Figure 1).