Supplementary Material for: Serum Phosphorus Levels are Associated with Intradialytic Hypotension in Hemodialysis Patients

<b><i>Background:</i></b> Intradialytic hypotension (IDH) is a common serious complication in hemodialysis (HD) patients. Hyperphosphatemia is also common in HD patients and promotes vascular calcification. Given the association between vascular calcification and IDH, we investigated the association between IDH and serum phosphorus in HD patients. <b><i>Methods:</i></b> We enrolled 173 patients who received HD for 3 months or more. IDH was defined as a nadir systolic blood pressure (SBP) &lt;90 mm Hg or as a decrease in SBP ≥20 mm Hg or a decrease in mean arterial pressure by 10 mm Hg with the occurrence of hypotension-related symptoms requiring intervention. Serum phosphorus levels were analyzed both as a continuous variable and as a categorical variable. <b><i>Results:</i></b> IDH occurred in 40 (23.1%) of the 173 patients. The mean phosphorus level was 4.9 mg/dL. A 1 mg/dL higher serum phosphorus resulted in a 2.1-fold greater odds of IDH. The fully adjusted odds ratio (OR) and 95% confidence interval (CI) were 2.11 (1.48–3.01). High categorized phosphorus levels were also associated with IDH. The highest tertile of serum phosphorus was associated with 6.5-fold greater odds of developing IDH compared to the referent group (the middle tertile of serum phosphorus, 4.0–&lt;5.3 mg/dL); the fully adjusted OR (95% CIs) were 6.53 (2.23–19.09). In subgroup analyses, diabetes and pre-dialysis SBP modified the association between IDH and phosphorus levels, with a more pronounced association in diabetic patients and pre-dialysis SBP ≥140 mm Hg. <b><i>Conclusion:</i></b> In HD patients, higher phosphorus levels were associated with an increased occurrence of IDH.

**背景**：透析中低血压（Intradialytic Hypotension, IDH）是血液透析（Hemodialysis, HD）患者常见的严重并发症。高磷血症在血液透析患者中也较为普遍，且可促进血管钙化。鉴于血管钙化与透析中低血压存在关联，本研究旨在探讨血液透析患者体内透析中低血压与血清磷水平的相关性。

**方法**：本研究纳入了173例接受血液透析治疗时长≥3个月的患者。透析中低血压的判定标准为：收缩压（Systolic Blood Pressure, SBP）最低值＜90 mmHg，或收缩压降幅≥20 mmHg，或平均动脉压降幅达10 mmHg且伴随需临床干预的低血压相关症状。本研究将血清磷水平分别以连续变量与分类变量两种形式开展分析。

**结果**：173例患者中共有40例（23.1%）发生透析中低血压。受试者的平均血清磷水平为4.9 mg/dL。血清磷水平每升高1 mg/dL，患者发生透析中低血压的优势比升高2.1倍。经完全校正后的优势比（Odds Ratio, OR）与95%置信区间（Confidence Interval, CI）为2.11（1.48~3.01）。血清磷水平升高的分类分组同样与透析中低血压存在关联。与参照组（血清磷水平处于中间三分位组，即4.0~＜5.3 mg/dL）相比，血清磷水平最高三分位组患者发生透析中低血压的优势比升高6.5倍；经完全校正后的优势比（95%置信区间）为6.53（2.23~19.09）。亚组分析结果显示，糖尿病状态与透析前收缩压水平会对透析中低血压与血清磷水平的相关性产生修饰作用，在糖尿病患者及透析前收缩压≥140 mmHg的人群中，二者的关联更为显著。

**结论**：在血液透析患者中，血清磷水平升高与透析中低血压发生率升高存在显著相关性。