Raw Bioelectrical Impedance Analysis Variables Are Independent Predictors of Early All-Cause Mortality in Patients With COPD
Raw Bioelectrical Impedance Analysis Variables Are Independent Predictors of Early All-Cause Mortality in Patients With COPD
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DOI：
10.1016/j.chest.2019.01.001
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发表时间：
2019-06-01
期刊：
影响因子：
9.6
通讯作者：
de Blasio, Francesco
中科院分区：
文献类型：
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作者：
de Blasio, Francesca;Scalfi, Luca;de Blasio, Francesco
背景：生物电阻抗分析（BIA）是一种有价值的方法，通过使用特定的预测方程来估计COPD患者的无脂质量和脂肪质量。此外，原始BIA变量，如高低频阻抗比（IRs）和相位角，很可能是提供肌肉质量信息的结果，与几种疾病患者的疾病严重程度和死亡率相关，但与COPD无关。本研究的目的是探讨原始BIA变量对COPD患者2年生存率的预测作用。方法：测定210例COPD患者5-10-50-100-250 kHz的阻抗(Z)和50 kHz的相位角。计算三个IR: 50 kHz的Z /5 kHz的Z (50/5 IR)， 100 kHz的Z /5 kHz的Z （100/5 IR）和250 kHz的Z /5 kHz的Z （250/5 IR）。记录基线时的人口统计、呼吸和身体成分数据。在2年随访期间评估全因死亡率。结果：随访后全因死亡率为13.8%。在年龄、体重、BMI、FEV i、吸气量和改良的医学研究委员会呼吸困难评分方面，非幸存者和幸存者之间存在统计学上的显著差异。在营养变量方面，与幸存者相比，非幸存者具有较低的无脂质量（P = 0.031），较低的脂肪质量（P = 0.015），较高的IRs（所有比率P < 0.001）和较低的相位角（P < 0.001）。校正混杂因素后，IRs每增加一个单位和相位角每减少一个单位与死亡风险增加相关。结论：IRs和相位角作为原始BIA变量，是COPD全因死亡率的独立且强有力的预测因素，应与吸气量和6分钟步行距离一起考虑，作为中短期的重要预后因素。
BACKGROUND: Bioelectrical impedance analysis (BIA) is a valuable method for estimating fat-free mass and fat mass in patients with COPD by using specific predictive equations. In addition, raw BIA variables such as high- to low-frequency impedance ratios (IRs) and phase angle, most likely as a result of providing information on muscle quality, have been related to disease severity and mortality in patients with several diseases but never in COPD. The aim of this study was to investigate the predictive role of raw BIA variables on 2-year survival in COPD.METHODS: Impedance (Z) at 5-10-50-100-250 kHz and phase angle at 50 kHz were determined in 210 patients with COPD. Three IRs were calculated: Z at 50 kHz/Z at 5 kHz (50/5 IR), Z at 100 kHz/Z at 5 kHz (100/5 IR), and Z at 250 kHz/Z at 5 kHz (250/5 IR). Demographic, respiratory, and body composition data at baseline were recorded. All-cause mortality was assessed during 2 years of follow-up.RESULTS: After the follow-up period, all-cause mortality was 13.8%. Statistically significant differences between nonsurvivors and survivors emerged in terms of age, weight, BMI, FEV i , inspiratory capacity, and modified Medical Research Council dyspnea score. With respect to nutritional variables, nonsurvivors had lower fat-free mass (P = .031), lower fat mass (P = .015), higher IRs (P < .001 for all the ratios), and lower phase angle (P < .001) compared with survivors. After adjustment for confounding factors, each unit increase of IRs and each unit decrease of phase angle were associated with a higher risk of death.CONCLUSIONS: IRs and phase angle, as raw BIA variables, are independent and powerful predictors of all-cause mortality in COPD and should be considered, together with inspiratory capacity and 6-min walk distance, as significant prognostic factors in the short- to middle-term.