Validity of the Japanese version of functional assessment of cancer therapy-gastric (FACT-Ga) and its sensitivity to ascites volume change: a retrospective analysis of Japanese clinical trial participants

Abstract

Purpose

The functional assessment of cancer therapy-gastric (FACT-Ga) questionnaire was designed to evaluate quality of life (QOL) in patients with gastric cancer. We aimed to explore the reliability and validity of FACT-Ga in Japanese patients, and assess the sensitivity of the gastric cancer subscale for detecting changes in cancer-related variables over time.

Methods

The Japanese version of FACT-Ga was used, and data were obtained from Japanese patients who participated in either of two clinical trials: treatment for advanced or recurrent gastric cancer with ascites (advanced-GC group), or adjuvant chemotherapy after curative resection of gastric cancer (adjuvant group). Psychometric data including data used to determine reliability, internal consistency, and clinical validity were analyzed. Clinical validity was evaluated by comparing subscale scores for patients in the two groups, and by comparing subscale scores for patients with different performance status scores. Correlation between gastric cancer subscale scores and gastric cancer-related variables was also examined. In addition, sensitivity of the gastric cancer subscale to changes in ascites volume, abdominal girth, and Eastern Cooperative Oncology Group (ECOG) performance status (PS) was examined by evaluating their correlation in the advanced-GC group.

Results

We collected data on 156 patients (62 advanced-GC group patients and 94 adjuvant group patients). Response rates for the subscales were over 80 % at most time points for both the groups. Cronbach's coefficient alpha revealed good internal consistency for each subscale. At baseline, the adjuvant group had higher QOL scores than the advanced-GC group (P < 0.05), and QOL scores for patients with different performance status scores differed significantly. Changes in gastric cancer subscale scores showed statistically significant correlation with changes in ascites volume (Spearman's rank correlation coefficient, 0.5; P < 0.05).

Conclusions

FACT-Ga is reliable and clinically valid for Japanese patients with gastric cancer. Detection of QOL changes that correlate with ascites volume changes suggests that it could be used more broadly; FACT-Ga scores could be used as an endpoint for patients with gastric cancer-related ascites.

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