RELIABILITY AND LIMITS OF AGREEMENT OF CIRCUMFERENTIAL, WATER DISPLACEMENT, AND OPTOELECTRONIC VOLUMETRY IN THE MEASUREMENT OF UPPER LIMB LYMPHEDEMA

Abstract

We conducted a reliability comparisonstudy to determine the intrarater andinterrater reliability and the limits ofagreement of the volume estimated bycircumferential measurements using thefrustum sign method and the disk modelmethod, by water displacement volumetry,and by infrared optoelectronic volumetry inthe assessment of upper limb lymphedema.Thirty women with lymphedema followingaxillary lymph node dissection surgery forbreast cancer surgery were enrolled. Ineach patient, the volumes of the upper limbswere estimated by three physical therapistsusing circumference measurements, waterdisplacement and optoelectronic volumetry.One of the physical therapists performedeach measure twice. Intraclass correlationcoefficients (ICCs), relative differences, andlimits of agreement were determined.Intrarater and interrater reliability ICCsranged from 0.94 to 1. Intrarater relativedifferences were 1.9% for the disk modelmethod, 3.2% for the frustum sign modelmethod, 2.9% for water displacementvolumetry, and 1.5% for optoelectronicvolumetry. Intrarater reliability was alwaysbetter than interrater, except for theoptoelectronic method. Intrarater andinterrater limits of agreement werecalculated for each technique. The diskmodel method and optoelectronic volumetryhad better reliability than the frustum signmethod and water displacement volumetry,which is usually considered to be the goldstandard. In terms of low-cost, simplicity,and reliability, we recommend the diskmodel method as the method of choice inclinical practice. Since intrarater reliabilitywas always better than interrater reliability(except for optoelectronic volumetry),patients should therefore, ideally, always beevaluated by the same therapist.Additionally, the limits of agreement mustbe taken into account when determining theresponse of a patient to treatment.