Measuring quality of life in patients with breast cancer: a systematic review of reliable and valid instruments available in Japan

BACKGROUND: Little is known about the availability and psychometric properties of instruments to measure quality of life (QOL) in clinical research on Japanese patients with breast cancer. The purpose of this systematic review is to find reliable and valid instruments available in Japan, and to summarize their characteristics. METHODS: Instruments available in Japan were found through a systematic search of the literature. Each instrument identified was evaluated for item development, reliability, validity, interpretability and utility. RESULTS: Six questionnaires to measure health-related QOL (the QOL-ACD, the EORTC QLQ-C30, the EORTC QLQ-BR23, the FACT-B, the SF-36, the WHO/QOL-26) and five scales to quantify the psychological burden (the STAI, the POMS, the SDS, the HADS, the GHQ), for which reliability and validity have been documented, are available in Japanese. All instruments were developed in foreign countries except for the QOL-ACD. Two of the QOL questionnaires were specific to breast cancer (the EORTC QLQ-BR23, the FACT-B). Though the measurements can be interpreted in some manner, the meaning of change scores over time has been documented for only three instruments (the EORTC QLQ-C30, the FACT-B, and the GHQ). CONCLUSIONS: The review provides grounds for designing and implementing quantitative research on QOL of breast cancer patients in Japan. Methodological challenges, however, continue, particularly for validating instruments with regard to various study populations of Japanese people and demonstrating the clinical importance of change scores.