Measuring fatigue and other anemia-related symptoms with the Functional Assessment of Cancer Therapy (FACT) measurement system

Abstract

This paper reports the development and validation of a questionnaire assessing fatigue and anemia-related concerns in people with cancer. Using the 28-item Functional Assessment of Cancer Therapy-General (FACT-G) questionnaire as a base, 20 additional questions related to the symptoms and concerns of patients with anemia were developed. Thirteen of these 20 questions dealt with fatigue, while the remaining 7 covered other concerns related to anemia. Using semi-structured interviews with 14 anemic oncology patients and 5 oncology experts, two instruments were produced: The FACT-Fatigue (FACT-F), consisting of the FACT-G plus 13 fatigue items, and the FACT-Anemia (FACT-An), consisting of the FACT-F plus 7 nonfatigue items. These measures were, in turn, tested on a second sample of 50 cancer patients with hemoglobin levels ranging from 7 to 15.9 g/dL. The 41-item FACT-F and the 48 item FACT-An scores were found to be stable (test-retest r = 0.87 for both) and internally consistent (coefficient alpha range = 0.95-0.96). The symptom-specific subscales also showed good stability (test-retest r range = 0.84-0.90), and the Fatigue subscale showed strong internal consistency (coefficient alpha range = 0.93-0.95). Internal consistency of the miscellaneous nonfatigue items was lower but acceptable (alpha range = 0.59-0.70), particularly in light of their strong relationship to patient-rated performance status and hemoglobin level. Convergent and discriminant validity testing revealed a significant positive relationship with other known measures of fatigue, a significant negative relationship with vigor, and a predicted lack of relationship with social desirability. The total scores of both scales differentiated patients by hemoglobin level (p < 0.05) and patient-rated performance status (p < 0.0001). The 13-item Fatigue subscale of the FACT-F and the 7 nonfatigue items of the FACT-An also differentiated patients by hemoglobin level (p < 0.05) and patient-rated performance status (p < or = 0.001). The FACT-F and FACT-An are useful measures of quality of life in cancer treatment, adding more focus to the problems of fatigue and anemia. The Fatigue Subscale may also stand alone as a very brief, but reliable and valid measure of fatigue.