Prospective evaluation of the reliability, validity, and minimally important difference of the functional assessment of cancer therapy-gastric (FACT-Ga) quality-of-life instrument

Abstract

BACKGROUND: Recently, the Functional Assessment of Cancer Therapy-Gastric (FACT-Ga) was developed to measure the quality of life (QoL) of patients with gastric cancer. This newly developed instrument has not yet been validated. METHODS: Eighty-two patients with gastric adenocarcinoma completed questionnaires at baseline. The FACT-Ga scores were measured as a function of disease stage and performance status, and they were correlated with the Medical Outcomes Study 36-item short-form health survey (SF-36), the Beck Depression Inventory-II, the Marlow-Crowne Social Desirability Scale, the Paulhus Deception Scale, and the State-Trait Anxiety Inventory. Patients received a second questionnaire 2 weeks after baseline to evaluate test-retest reliability and again at 3 months to evaluate the sensitivity of the FACT-Ga to changes in performance status and to estimate the minimally important differences in scores that represented meaningful change. RESULTS: The internal and test-retest reliability of the FACT-Ga instrument was adequate. With the exception of the social well being subscale, all FACT-Ga scores were correlated as hypothesized with other measures. Relevant components of the FACT-Ga were sensitive to changes in performance status. CONCLUSIONS: The current results indicated that the FACT-Ga provides a valid and reliable measurement of QoL in patients with gastric adenocarcinoma. It is a useful instrument for QoL assessment in clinical trials, and it also may be useful for the detection of significant changes in the QoL of individual patients. © 2010 American Cancer Society.