Assessing fatigue in persons with cancer: further validation of the Wu Cancer Fatigue Scale.

Cancer-related fatigue (CRF) is a significant clinical symptom. Effective assessment of CRF attributes from the patients' perspective is essential. This study tested the psychometric properties of the Wu Cancer Fatigue Scale (WCFS). A total of 172 outpatients with breast cancer, who were at various stages and on various chemotherapy regimens, and were undergoing treatment at one of three cancer clinics in a Midwest metropolitan area, participated in this study. The participants were instructed to complete four instruments in the following order: the 16-item WCFS, Schwartz Cancer Fatigue Scale (SCFS), Geriatric Depression Scale (GDS), and Cancer-Related Fatigue Distress Scale (CRFDS). Structural equation modeling (LISREL 8.54) supported the one-factor measurement model with nine items remaining. Nonsignificant Satorra-Bentler Scaled Chi-square (27)=32.52, P=0.21, standardized root mean square residual=0.032, nonnormal fit index=0.97, comparative fit index=0.98, and incremental fit index=0.98 indicated a good model fit. Convergent validity with the SCFS was 0.78, concurrent validity with the GDS was 0.60, and predictive validity with the CRFDS was 0.73. Internal consistency reliability was alpha=0.91 for the nine-item scale. The revised WCFS is a reliable and valid instrument that aims to measure the subjective characteristics of CRF from the patients' perspective. It may prove useful in both clinical and research settings.