Supplementary Material for: Peripheral Eosinophil Count Associated with Disease Activity and Clinical Outcomes in Hospitalized Patients with Lupus Nephritis

<b><i>Introduction:</i></b> The aim of this study was to evaluate the association of peripheral eosinophil (EOS) count with disease activity and kidney outcomes in lupus nephritis (LN) patients. <b><i>Methods:</i></b> A total of 453 hospitalized and biopsy-proven LN patients at our hospital from 2006 to 2013 were enrolled, of which 388 patients had repeated measurements of EOS. Relationships were explored between average EOS and disease activity at baseline, using the systemic lupus erythematosus disease activity (SLEDAI) and activity index (AI) on kidney biopsy. Follow-up data were available through December 2016. The primary outcome measure was a composite of doubling of serum creatinine and end-stage kidney disease after a median follow-up of 51 months. <b><i>Results:</i></b> The mean age of the enrolled 388 LN patients was 33.1 ± 10.8 years old, and 335 (86%) were female. The median average peripheral EOS count was 0.033 (0.015–0.057) ×10⁹/L. Mean AI and SLEDAI score were 6.8 ± 2.5 and 14.9 ± 5.4, respectively. Logistic regression models showed that decreased average EOS was independently associated with higher AI (≥6) and higher SLEDAI (≥15) (odds ratio [OR] 0.93, 95% confidence interval [CI] 0.90–0.97; and OR 0.96, 95% CI: 0.93–0.99, respectively). There was a parabolic relationship between average EOS and the primary outcome, with hazard ratio (HR) &gt; 1 for both levels ≤0.033 and &gt;0.16 × 10⁹/L. <b><i>Conclusion:</i></b> Lower EOS count was independently associated with severe disease activity and kidney progression in LN.

<b><i>引言：</i></b> 本研究旨在评估狼疮肾炎（lupus nephritis, LN）患者外周血嗜酸性粒细胞（eosinophil, EOS）计数与疾病活动度及肾脏预后的关联。
<b><i>方法：</i></b> 本研究纳入2006年至2013年于本院就诊且经肾活检确诊的453例住院狼疮肾炎患者，其中388例具备嗜酸性粒细胞的重复检测数据。以基线时的系统性红斑狼疮疾病活动指数（systemic lupus erythematosus disease activity index, SLEDAI）及肾活检活动指数（activity index, AI）评估疾病活动度，分析平均嗜酸性粒细胞计数与基线疾病活动度的相关性。随访数据截止至2016年12月，中位随访时长为51个月，主要终点为血清肌酐翻倍及终末期肾病的复合结局。
<b><i>结果：</i></b> 纳入分析的388例狼疮肾炎患者平均年龄为33.1±10.8岁，其中女性335例（占比86%）。外周血平均嗜酸性粒细胞计数的中位值为0.033（0.015~0.057）×10⁹/L。肾活检活动指数及SLEDAI评分的平均值分别为6.8±2.5与14.9±5.4。Logistic回归分析显示，平均嗜酸性粒细胞计数降低与更高的肾活检活动指数（≥6分）及更高的SLEDAI评分（≥15分）独立相关（比值比（odds ratio, OR）=0.93，95%置信区间（confidence interval, CI）：0.90~0.97；比值比（odds ratio, OR）=0.96，95%置信区间（confidence interval, CI）：0.93~0.99）。平均嗜酸性粒细胞计数与主要终点呈抛物线关系：当嗜酸性粒细胞计数≤0.033×10⁹/L或>0.16×10⁹/L时，风险比（hazard ratio, HR）均大于1。
<b><i>结论：</i></b> 狼疮肾炎患者外周血嗜酸性粒细胞计数降低与严重疾病活动度及肾脏疾病进展独立相关。