Reference Ranges Using Bioimpedance for Detection of Lymphedema in Chinese Women.
Bioimpedance is a commonly used technique for detection of early lymphedema. The thresholds used for detection are based on impedance measurements obtained in Western populations. It is unknown whether these thresholds are applicable to a Chinese population. Impedance measurements were obtained for both arms in 391 women, ranging in age from 20 to 84 years, using a standardized protocol. Frequency distributions of interlimb impedance arm ratios for both dominant:non-dominant and non-dominant:dominant were used to determine thresholds at two and three standard deviations (SDs) above the mean. Absolute impedance was significantly higher in the youngest group (20-39 years) compared to other age groups. However, there was no significant effect of age on impedance ratios. Similarly, there was no significant difference between impedance ratios determined in this study and those from recent studies in the Australia and the United States, which used similar protocols. New two and three SDs above the mean thresholds, using a weighted average from the pooled data of these studies are 1.108 and 1.153 for use when the dominant limb is at-risk and 1.072 and 1.116 when the non-dominant limb is at-risk. There was no effect of ethnicity on impedance ratios. Consequently, the proposed pooled thresholds can be used, irrespective of ethnicity.