Background: The aim of the present prospective study (ClinicalTrials.gov Identifier: NCT02111538) was to assess the prognostic value of phase angle (PhA), derived from bioimpedance vectorial analysis (BIVA), in patients affected by systemic amyloid light-chain (AL) amyloidosis.

Methods: One hundred-twenty seven consecutive newly diagnosed, treatment-naïve patients with histologically confirmed AL amyloidosis were enrolled. Nutritional assessment including BIVA-derived PhA was performed before treatment initiation.

Results: PhA was associated with unintentional weight loss, caloric intake and the physical component of quality of life (QoL). After a median follow-up of 16.3 months (25th–75th percentile: 8.4–28.9 months), 49 (38.6%) subjects had died. At multivariable Cox proportional hazard analysis, PhA ≤4.3 independently predicted survival (HR = 2.26 [95%CI, 1.04–4.89]; p = .038]) after controlling for hydration status, haematologic response to treatment and modified Mayo Clinic cardiac stage. There was no effect modification of PhA on mortality by cardiac stage (P for interaction = 0.61).

Conclusions: In AL amyloidosis, BIVA-derived PhA is associated with the common parameters implied in malnutrition assessment and QoL, and adjusted for hydration independently predicts survival. Due to its feasibility, BIVA should be systematically considered for the nutritional and clinical assessment of AL patients, in whom nutritional intervention trials are warranted.

背景：本前瞻性研究（ClinicalTrials.gov标识符：NCT02111538）的目的是评估由生物阻抗矢量分析（BIVA）得出的相角（PhA）对受系统淀粉样蛋白轻链（AL）影响的患者的预后价值）淀粉样变性。

方法：招募了一百二十七名经组织学证实为AL淀粉样变性的新诊断，未接受过治疗的患者。在治疗开始之前进行了包括BIVA衍生的PhA在内的营养评估。

结果： PhA与意外体重减轻，热量摄入和生活质量（QoL）的生理因素有关。在中位随访16.3个月（25％至75％百分位数：8.4-28.9个月）之后，有49名（38.6％）的受试者死亡。在多变量Cox比例风险分析中， 控制水合状态，对治疗的血液学反应和改良的Mayo临床心脏分期后，PhA≤4.3可独立预测存活率（HR = 2.26 [95％CI，1.04-4.89]；p = .038] 。PhA对心脏分期的死亡率没有影响（交互作用的P = 0.61）。

结论：在AL淀粉样变性病中，BIVA衍生的PhA与营养不良评估和QoL暗示的通用参数相关联，并且调整水合作用可独立预测存活率。由于其可行性，应系统地考虑将BIVA用于需要进行营养干预试验的AL患者的营养和临床评估。