Clinical relevance of fatigue levels in cancer patients at a Veterans Administration Medical Center

Background: The correlation of fatigue levels with functional interference, symptom distress, and quality of life may help determine clinically significant fatigue levels.

Methods: One hundred eighty consecutive patients with cancer completed the Functional Assessment of Cancer Therapy (FACT) General and Fatigue subscales (FACT-G and FACT-F, respectively), the Memorial Symptom Assessment Scale-Short Form (MSAS-SF), the Depression Scale (Zung), and the Brief Fatigue Inventory (BFI). The Karnofsky performance status (KPS) was determined for each patient. Multivariate analyses of variance were performed to compare fatigue models with different cut-off points to categorize fatigue levels. Cox proportional hazards analysis was performed to assess the association between fatigue severity and survival.

Results: Increased fatigue levels were associated with greater symptom distress and decreased quality of life. A model with usual fatigue cut-off points of 0 (no fatigue), 1-2 (mild fatigue), 3-6 (moderate fatigue), and 7-10 (severe fatigue) was optimal in relation to functional interference items (Wilks lambda, 0.36; F = 11.61; P < 0.0001), symptom distress scores (Wilks lambda, 0.52; F = 10.41; P < 0.0001), and quality-of-life scores (Wilks lambda, 0.50; F = 0.50; P < 0.0001). Fatigue severity predicted survival in univariate analysis (chi-square test, 25.42; P < 0.0001). The KPS, stage of disease, and number of symptoms independently predicted survival in patients with fatigue.

Conclusions: Clinically relevant fatigue levels are correlated with symptom and quality-of-life measurements. Patients with a usual fatigue severity > 3 or a worst fatigue severity > 4 on a 1-10 scale may require further assessment.