Convergent validity of shoulder range of motion measurement methods in breast cancer patients.

Abstract

Upper limb dysfunctions are common in breast cancer patients, requiring valid range of motion (ROM) assessment methods. This cross-sectional study evaluates the convergent validity of an Inertial Measurement Unit set-up (IMUs) and three clinical tools: analogue goniometry, analogue inclinometry, and digital goniometry. Secondly, it examines agreement between these clinical tools. Humerothoracic and scapulothoracic upward rotation ROM were assessed during six movement tasks. Correlation analyses studied convergent validity. Agreement and interchangeability were assessed using interclass correlation coefficients (ICCs), Bland-Altman plots, and limits of agreement. Thirty participants were included (median age 52.50 [45.75-59.00] years). For humerothoracic ROM, clinical tools measured similar constructs (<i>r</i> = 0.609-0.949), and the IMUs show no or related outcomes (<i>r</i> = 0.078-0.809). The clinical tools showed good agreement (ICC = 0.816-0.985); however, systematic biases and outliers were present. For scapulothoracic ROM, results indicated that clinical tools mostly measured similar constructs (<i>r</i> = 0.205-0.888), while the IMUs measured unrelated constructs (<i>r</i> = -0.316-0.511). Moderate to excellent relative agreement was presented (ICC = 0.502-0.936), but with wide variability (up to 27.5°). Clinical tools evaluate similar constructs for humerothoracic and scapulothoracic ROM, but vary for the IMUs. Results suggest not using the tools interchangeably for scapulothoracic ROM due to clinically significant differences.