Jönsson Charlotta, Johansson Karin, Bjurberg Maria, Brogårdh Christina
Department of Health Sciences, Lund University, Lund, Sweden.
Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden.
Phys Ther. 2022 May 5;102(5). doi: 10.1093/ptj/pzac025.
Lower limb lymphedema (LLL) is a chronic condition. To be able to evaluate changes of LLL over time and effects of interventions, reliable measurement methods are important. Currently, there is limited knowledge of the reliability of commonly used measurement methods in LLL. The study objective was to evaluate the test-retest (intrarater) reliability of impedance of extracellular fluid, volume, and local tissue water measurements in people with unilateral or bilateral LLL and measurement errors both for a group of people and for a single individual.
Forty-two people with mild to moderate unilateral or bilateral, primary or secondary LLL were measured twice, 2 weeks apart. Impedance of extracellular fluid was measured by bioimpedance spectroscopy and calculated as arm-to-leg ratio, volume with circumference measurements every 4 cm, and local tissue water with tissue dielectric constant at 14 points. Test-retest reliability was evaluated using the intraclass correlation coefficient [ICC(2,1)], changes in the mean, SE of measurement in relative terms (SEM%), and the smallest real difference in relative terms (SRD%).
For the impedance ratio, the reliability was high [ICC(2,1) = 0.79-0.90] and the measurement errors were acceptable (SEM% = 5.0%-5.2%; SRD% = 14.0%-14.4%). For volume, the reliability was high (ICC = 0.99) and the measurement errors were low (SEM% = 1.1%-1.7%; SRD% = 3.1%-4.6%). For the tissue dielectric constant, the reliability was fair to excellent [ICC(2,1) = 0.68-0.96] and the measurement errors were acceptable (SEM% = 4.2%-9.7%; SRD% = 11.7%-26.8%).
Measurements of impedance of extracellular fluid, volume, and local tissue water are reliable in people with mild to moderate LLL. The measurement errors were acceptable in all 3 methods indicating that real, clinical changes in lymphedema can be measured both for a group of people and a single individual.
The results from this test-retest reliability study can help clinicians and researchers to interpret if real clinical changes in lymphedema occur over time or after an intervention in people with mild to moderate LLL.
下肢淋巴水肿（LLL）是一种慢性疾病。为了能够评估LLL随时间的变化以及干预效果，可靠的测量方法很重要。目前，对于LLL中常用测量方法的可靠性了解有限。本研究的目的是评估单侧或双侧LLL患者细胞外液阻抗、体积和局部组织水分测量的重测（同一测量者）可靠性，以及一组人和单个个体的测量误差。
42例轻度至中度单侧或双侧原发性或继发性LLL患者，间隔2周测量两次。细胞外液阻抗通过生物电阻抗光谱法测量，并计算臂腿比值；体积通过每4厘米测量一次周长来确定；局部组织水分通过14个点的组织介电常数来测量。使用组内相关系数[ICC(2,1)]、均值变化、相对测量标准误（SEM%）和相对最小真实差异（SRD%）评估重测可靠性。
对于阻抗比值，可靠性较高[ICC(2,1)=0.79 - 0.90]，测量误差可接受（SEM% = 5.0% - 5.2%；SRD% = 14.0% - 14.4%）。对于体积，可靠性较高（ICC = 0.99），测量误差较低（SEM% = 1.1% - 1.7%；SRD% = 3.1% - 4.6%）。对于组织介电常数，可靠性从中等到优秀[ICC(2,1)=0.68 - 0.96]，测量误差可接受（SEM% = 4.2% - 9.7%；SRD% = 11.7% - 26.8%）。
轻度至中度LLL患者的细胞外液阻抗、体积和局部组织水分测量是可靠的。所有3种方法的测量误差均可接受，表明无论是一组人还是单个个体，都可以测量出淋巴水肿的真实临床变化。
这项重测可靠性研究的结果可以帮助临床医生和研究人员判断轻度至中度LLL患者的淋巴水肿在一段时间内或干预后是否发生了真实的临床变化。
