Test-Retest Reliability of Volume and Local Tissue Water Measurements in Lower Limbs of Healthy Women and Men

Background: Measurements of lower limb (LL) volume and local tissue water by tissue dielectric constant (TDC) are common in lymphedema management. Knowledge of normal variability in health subjects is important and can serve as a base for early lymphedema diagnosis but is currently lacking. The aim of this study was to evaluate test-retest reliability of LL volume and TDC values in healthy women and men. Methods and Results: Thirty-three women and 28 men were measured twice, 2 weeks apart. Volume was calculated from circumferential measurements every 4 cm and TDC in 14 points. Test-retest reliability was evaluated using intraclass correlation coefficient (ICC), changes in the mean, standard error of measurement in percentage (SEM%), and smallest real difference in percentage (SRD%). For volume, reliability was high (ICC 0.99) and measurement errors were low in both women and men (SEM%: 1.1%-1.3%; SRD%: 3.1%-3.6%). For TDC, reliability was fair to excellent in women (ICC 0.63-0.93) and poor to excellent in men (ICC 0.21-0.89). Measurement errors were acceptable in all points in women (SEM%: 3.9%-10.2%; SRD% 10.8%-28.2%), but only in 11 points in men (SEM%: 3.9%-14.5%; SRD%: 10.9%-40.1%). The points close to bone and tendons in men had lower reliability and higher measurement errors. Conclusion: Measurements of LL volume and TDC are reliable in healthy women and men; both methods can be recommended. However, TDC points close to bone and tendons in men should be used with caution.