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

Abstract

Purpose: 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.

Materials and methods: 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.

Results: Thirty participants were included (median age 52.50 [45.75-59.00] years). For humerothoracic ROM, clinical tools measured similar constructs (r = 0.609-0.949), and the IMUs show no or related outcomes (r = 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 (r = 0.205-0.888), while the IMUs measured unrelated constructs (r = -0.316-0.511). Moderate to excellent relative agreement was presented (ICC = 0.502-0.936), but with wide variability (up to 27.5°).

Conclusions: 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.