Reliability study of measurements for lymphedema in breast cancer patients

Objective: Water displacement, circumference measurement, and tissue tonometry are important methods to evaluate the status of lymphedemous limbs in breast cancer patients. The purpose of this study was to investigate the reliabilities, and define the limits for clinical change indicative of clinical improvement with respect to these three measures. Design: Fourteen patients were recruited for water displacement and circumference measurement, and 17 for tissue resistance by tonometry. All had been treated for breast cancer and subsequently developed lymphedema. Two physical therapists conducted the measurements to determine intra- and interrater reliability. Results: All measures had fair to excellent reliability (water displacement and circumference measurement, intraclass correlation coefficient [ICC] >0.99, P < 0.05; tissue tonometry, 0.66 < ICC < 0.88, P < 0.05). There was no systematic change in the mean for any of the measures. The variation, as determined by standard error of measurement (SEM), SEM%, smallest real difference (SRD), and SRD% was greatest for tissue tonometry. Conclusions: Water displacement and circumference measurement (but not tonometry) are reliable techniques for assessing lymphedema in clinical practice. The effect of modifying the tonometry protocol and increasing the amount of rater training should be studied to determine whether the reliability of this method can be improved.