Reliability and Validity of Self-measured Arm Circumference in Women With Breast Cancer

Purpose: to test the reliability and validity of self-measured arm circumference compared to measures performed by a specialized therapist and by the perometer (gold standard). The hypothesis is that there will be an excellent correlation between arm circumference measures performed by the participant and by an experienced physiotherapist and a moderate correlation between arm circumference measures performed by the patient and determined by perometer, as well as arm volume calculated from arm circumference measurements and measured by the perometer. Design: A cross-sectional study of women at risk of breast cancer-related lymphedema (BCRL) (n=20) and with BCRL (n=20) Procedures: Participants will complete one self-assessment at home and one self-assessment at a laboratory the University of British Columbia (UBC). Home Self-assessment: Participants will be sent a study package by mail, which will contain the consent form, a tape measure, written instructions supplemented with illustrations, a link for a video guide, and a measurement form, along with an opaque envelop for the measurement form. Participants will be asked to first review the written and video material outlining the measurement process, prior to completing a short self-assessment quiz on the self-measurement technique. Participants will then perform arm circumference measures of both arms as per the instructions, record the measurements on the provided form and seal the form in a provided envelope. The envelope will be returned to the study team at the lab assessment. Lab Self-assessment: At the visit at UBC, participants will be asked by study staff to repeat these arm circumference measures with support from the video and written instructions, unsupervised by a physiotherapist. This will be followed by an assessment by the physiotherapist and measures with the perometer. Statistical analysis plan: Intra-rater (between self-measures performed at home and at the lab), inter-rater reliability (between self-measures performed at lab and therapist-measures) and concurrent validity analysis (between self-measures performed at lab and perometer measures) will be conducted separately for women with and without BCRL.