Objective measurement of cancer-related fatigue

This narrative review summarizes objective measures of cancer-related fatigue (CRF), their clinical and research utility, and their value in clinical practice and research. Objective measures are recommended where cognitive and physical CRF are the primary research outcomes of the studies reviewed.

This narrative review was done in two phases. The first, in 2018, evaluated CRF-focused studies published through peer review, and the second, from February 1, 2018, to March 31, 2024, included search results to identify more recent CRF articles. PubMed, Science Direct, and Scopus were used for the search. In both review phases, articles were excluded if they were abstracts only, editorials, or letters to the editor.

The literature searches resulted in 16,332 articles captured, 16,324 excluded, and 8 included. The review and analysis resulted in the discovery of 16 objective CRF assessments, categorized to correspond with their proposed CRF origin: central, peripheral, or both. Each assessment is described and outlined according to: (1) validated populations, (2) practicalities and clinical utility, and (3) applicability in the clinic space or bedside.

This review is the foundation for objective CRF measurement. Recommendations include actigraphy, electrical muscle stimulation, finger tapping test, laboratory measures, positron emission tomography, and sit-to-stand in combination with subjective CRF measures to inform correlations, management, and treatment. An increase in objective measure pathophysiology research will illuminate the "black box" that is CRF.