Quality of life assessment and reporting in randomized controlled trials: a study of literature published from Japan

BACKGROUND: Standardization of quality of life (QOL) assessment and reporting in clinical trials is an imperative issue. While English-speaking countries have led this movement in standardization, there persists to be a limited amount of information from non-English-speaking including Japan. In this study, we bibliographically analyze the reporting of randomized controlled trials (RCT) conducted in Japan that used a QOL instrument. METHODS: A PubMed search of reports published between 1970–2003 followed by an examination of QOL reporting and its frequency of use in RCTs published from Japan. RESULTS: Percentages of QOL reporting in RCTs have increased between 1970–2003 both worldwide (0% for 1970–1974 to 4.4% for 2000–2003) and in Japan (0% to 1.8% for the identical periods). We found and evaluated 46 RCT reports published from Japan (32 in English, 14 in Japanese). The most commonly studied clinical condition was cancer (26, 56.5%) and the most common intervention was drug therapy (29, 63.0%). QOL was used as the primary endpoint in 10 studies (21.7%). Authors used established QOL instruments in 12 studies (26.1%), developed original instruments in 8 studies (17.5%) and assessed the symptoms or performance status in 10 studies (21.7%). Authors conceptually defined QOL in only 6 studies (13.0%). Neither response rate nor number of respondents for questionnaire surveys was specified in 16 studies (34.8%); furthermore, 11 studies (23.9%) did not describe respondents' attributes. CONCLUSIONS: Findings on relative frequency suggested that Japanese authors of RCT reports have less interest in QOL instruments than other international researchers in Western Europe and North America. Examination of RCT reports published from Japan revealed that there were several points to be improved in reporting QOL instruments. This study highlights the need to define QOL measures specific to clinical specialty and to examine methodology for assessing and reporting QOL.