Test-retest reliability of arm volume measurement in women with breast cancer- related lymphoedema

Background: Arm volume is frequently calculated using arm circumferencemeasurements in a formula for frustum(truncated cone) volume. The circumferencesdivide the arm into segments. Summed segmentvolumes provide limb volume. Aim: To determine the test–retest reliability of segmentvolume and comparison of total arm volume reliability with and without segmentalreliability values, in both arms, in women with breast cancer-related lymphoedema (BCRL). Methods: Sixteen participants with unilateral BCRL (>6 months), completed cancer treatment. Circumferencemeasurements were performed twice, 1 week apart. Results: Hand measurement exhibited the lowest reliability, while standard error of measurement (SEM) was 47.1 mL for the contralateral and 78.8 mL for the lymphatic arm. Arm volume measurement reliability based on combined segmentreliabilities gave increased SEM for the contralateral arm (66.6 mL) and decreased SEM for the lymphatic arm (45.0 mL). Conclusions: Summing segmentvolumes may increase measurement error and mask segmentalinconsistency. Differences between segmentalresponses to treatment may be revealed via arm segmentalvolume measurements. Declaration of interest: None.