Intra- and Interrater Reliability and Concurrent Validity of a New Tool for Assessment of Breast Cancer–Related Lymphedema of the Upper Extremity

Objective: The goal of this study was to develop and assess intra- and interrater reliability and validity of a clinical evaluation tool for breast cancer–related lymphedema, for use in the context of outcome evaluation in clinical trials. Design: Blinded repeated measures observational study. Setting: Outpatient research laboratory. Participants: Breast cancer survivors with and without lymphedema (N=71). Interventions: Not applicable. Main Outcome Measure: The assessment of intraclass correlation coefficients (ICCs) for the Breast Cancer–Related Lymphedema of the Upper Extremity (CLUE) standardized clinical evaluation tool. Results: Intrarater reliability for the CLUE tool was ICC: 0.88 (95% confidence interval [95% CI], 0.71-0.96). Interrater reliability for the CLUE tool was ICC: 0.90 (95% CI, 0.79-0.95). Concurrent validity of the CLUE score (Pearson r) was 0.79 with perometric interlimb difference and 0.53 with the Norman lymphedema overall score. Conclusions: The CLUE tool shows excellent inter- and intrarater reliability. The overall CLUE score for the upper extremity also shows moderately strong concurrent validity with objective and subjective measures. This newly developed clinical, physical assessment of upper extremity lymphedema provides standardization and a single score that accounts for multiple constructs. Next steps include evaluation of sensitivity to change, which would establish usefulness to evaluate intervention efficacy.