Communicating vessels volumeter to measure upper extremity in lymphedema after breast cancer: reliability and criterion validity compared to the gold standard.

BACKGROUND: The traditional overflow method for measuring limb volume remains the gold standard, but many disadvantages still inhibit its routine use in clinical practice.

OBJECTIVE: To assess the intra-rater and inter-rater reliability and criterion validity of the 'communicating vessels volumeter' (CVV) for volume measurement of lymphedematous upper extremities (LUE) by using the overflow volumeter (OV) as the reference standard.

METHODS: Twelve LUE of 12 women undergoing mastectomy for breast cancer were measured three times each by three raters using both methods, totaling 216 volume measurements. Criterion validity was estimated by 33 volume measurements of one cylinder of known volume by three raters using both methods, totaling 198 measurements.

RESULTS: Measurement time was short with both CVV and OV. The intraclass correlation coefficient3,1 was high for both CVV and OV in intra-rater (0.99 vs 0.99) and inter-rater (0.99 vs 0.99) analyses. The bias between methods was low (7.50mL; 0.40%) and the limits of agreement were narrow (-5.80 to 6.50%). The volumes were statistically equal with a strong correlation (R2 =0.98) between methods. CVV was more accurate than OV (0.00 vs 0.02%) in cylinder measurements.

CONCLUSION: The high intra-rater and inter-rater reliability rates of CVV were comparable to those of OV, and the volumes resulting from LUE measurements were statistically equal in the two methods. Criterion validity rates indicated that CVV measurements were closer to the actual value of the cylinder than those obtained with the OV.