Optimizing Patient Positioning to Reduce Variation in the Measurement of Breast Cancer-Related Lymphedema

Prospective lymphedema screening is recommended for breast cancer patients. We observed interoperator variation in perometer-acquired arm volume measurements (P-AVMs) due to patient instability during measurements. We hypothesized that improved positioning during perometry would reduce P-AVM variability. Each arm was measured three times by each operator using a perometer. With the original configuration, P-AVM was performed by 2 operators in 30 patients and four cohorts of 5 to 6 operators in 5 volunteers. Repeatability, reproducibility, and gage precision/tolerance (P/T) ratio were calculated. A customized handlebar was installed to optimize patient positioning. P-AVMs were performed in 20 patients with both configurations. Student's t-test was used to compare variation. With the new configuration, P-AVMs were performed by three operators in five volunteers and five operators in three volunteers. Repeatability, reproducibility, and gage P/T ratio were calculated. For the original configuration, gage P/T ratio was 19.9% for two operators and 35.9% for four cohorts of five to six operators. One operator using the new handlebar decreased P-AVM variability by 28% (p = 0.02). For the new configuration, gage P/T ratio was 6.5% for three operators and 18.7% for five operators. Optimizing patient setup improved P-AVM accuracy. P-AVM accuracy is critical as lack of accuracy results in either overdiagnosis or underdiagnosis of lymphedema, which in turn results in either over- or undertreatment of this dreaded condition. A higher number of operators were associated with greater P-AVM variability.