High ankle-brachial index predicts cardiovascular events and mortality in hemodialysis patients with severe secondary hyperparathyroidism

Abstract Introduction: Vascular calcification related to severe secondary hyperparathyroidism (SHPT) is an important cause of cardiovascular and bone complications, leading to high morbidity and mortality in patients with chronic kidney disease (CKD) undergoing hemodialysis (HD). The present study aimed to analyze whether ankle-brachial index (ABI), a non-invasive diagnostic tool, is able to predict cardiovascular outcomes in this population. Methods: We selected 88 adult patients on HD for at least 6 months, with serum iPTH>1,000pg/mL. We collected clinical data, biochemical and hormonal parameters, and ABI (sonar-Doppler). Calcification was assessed by lateral radiography of the abdomen and by simple vascular calcification score (SVCS). This cohort was monitored prospectively between 2012 and 2019 for cardiovascular outcomes (death, myocardial infarction (MI), stroke, and calciphylaxis) to estimate the accuracy of ABI in this setting. Results: The baseline values were: iPTH: 1770±689pg/mL, P: 5.8±1.2 mg/dL, corrected Ca: 9.7±0.8mg/dL, 25(OH)vit D: 25.1±10.9ng/mL. Sixty-five percent of patients had ABI>1.3 (ranging from 0.6 to 3.2); 66% had SVCS≥3, and 45% aortic calcification (Kauppila≥8). The prospective evaluation (51.6±24.0 months), provided the following cardiovascular outcomes: 11% of deaths, 17% of nonfatal MI, one stroke, and 3% of calciphylaxis. After adjustments, patients with ABI≥1.6 had 8.9-fold higher risk of cardiovascular events (p=0.035), and ABI≥1.8 had 12.2-fold higher risk of cardiovascular mortality (p=0.019). Conclusion: The presence of vascular calcifications and arterial stiffness was highly prevalent in our population. We suggest that ABI, a simple and cost-effective diagnostic tool, could be used at an outpatient basis to predict cardiovascular events in patients with severe SHPT undergoing HD.

**摘要与引言**：与重症继发性甲状旁腺功能亢进症（secondary hyperparathyroidism, SHPT）相关的血管钙化是慢性肾脏病（chronic kidney disease, CKD）血液透析（hemodialysis, HD）患者出现心血管与骨骼并发症的重要诱因，可导致该类患者较高的发病率与死亡率。本研究旨在分析无创诊断工具踝肱指数（ankle-brachial index, ABI）能否预测该人群的心血管不良结局。

**研究方法**：本研究纳入88名接受至少6个月血液透析的成年患者，其血清全段甲状旁腺激素（iPTH）水平＞1000pg/mL。收集患者的临床资料、生化与激素参数，以及通过超声多普勒（sonar-Doppler）检测得到的踝肱指数。采用腹部侧位X线片与简易血管钙化评分（simple vascular calcification score, SVCS）评估血管钙化情况。本队列于2012年至2019年间进行前瞻性随访，记录心血管不良结局（死亡、心肌梗死（myocardial infarction, MI）、脑卒中以及钙化防御（calciphylaxis）），以评估踝肱指数在该研究场景中的预测准确性。

**研究结果**：受试者基线指标如下：iPTH为1770±689pg/mL，磷（P）为5.8±1.2mg/dL，校正血钙为9.7±0.8mg/dL，25(OH)维生素D为25.1±10.9ng/mL。65%的患者ABI＞1.3（范围0.6~3.2）；66%的患者SVCS≥3，45%存在主动脉钙化（Kauppila评分≥8分）。经过平均51.6±24.0个月的前瞻性随访，共出现以下心血管不良结局：11%的患者死亡，17%发生非致死性心肌梗死，1例脑卒中，3%出现钙化防御。经校正后，ABI≥1.6的患者发生心血管事件的风险升高8.9倍（p=0.035），ABI≥1.8的患者心血管死亡率升高12.2倍（p=0.019）。

**研究结论**：本研究人群中血管钙化与动脉僵硬的患病率极高。我们认为，作为一种简便且成本效益优异的诊断工具，踝肱指数可在门诊场景中用于预测重症继发性甲状旁腺功能亢进症血液透析患者的心血管不良事件。