A Comparison of Supine Versus Stand-on Bioimpedance Devices to Assess Breast Cancer-Related Lymphedema

Abstract

Background: While supine bioimpedance devices are used to evaluate for lymphedema (LE), stand-on devices are gaining popularity. Because research on differences in bioimpedance values between the two devices is limited, this study's purposes were to: (1) determine the average upper limb impedance values and inter-limb ratios for women who self-reported having (n = 34) or not having (n = 61) a history of LE, using a single-frequency supine device and a multifrequency stand-on device; (2) compare the level of agreement in inter-limb impedance ratios between the two devices; evaluate the percent agreement between the two devices in classifying cases of LE using established supine thresholds; and evaluate the percent agreement in classifying cases of LE between the supine device using previously established supine thresholds and the stand-on device using two published standing thresholds. Methods and Results: Bioimpedance measures were done using the two devices. For the entire sample, absolute impedance values for both the affected and unaffected limbs were significantly higher for the stand-on device in women with and without LE. Impedance values for the two methods were highly correlated. Bland-Altman analysis determined that for the entire range of impedance ratios the values for the two devices could not be used interchangeably. Conclusions: Findings suggest that the stand-on device can be a useful and valid tool to assess for LE. However, because agreement is not perfect, values obtained from the two devices should not be used interchangeably to evaluate for changes in impedance ratios, particularly for ratios of >1.20.

Keywords: bioimpedance; breast cancer; lymphedema.

Conflict of interest statement

No competing financial interests exist.

Figures

FIG. 1.

(A) Scatter plot of supine impedance ratios on the x-axis and standing impedance ratios on the y-axis, including a diagonal line of equality (n = 95). (B) Bland–Altman plot with the mean impedance ratios for both methods on the x-axis and the difference in impedance ratios between the two methods on the y-axis (n = 95). (C) Scatter plot for participants with ratios of ≤1.20, with the supine impedance ratios on the x-axis and standing impedance ratios on the y-axis, including diagonal line of equality (n = 90). (D) Bland–Altman plot for participants with ratios ≤1.20, with the mean impedance ratios for both methods on the x-axis and the difference in impedance ratios between the two methods on the y-axis (n = 90).