Assessing the number, characteristics and quality of randomized controlled trials conducted in Japan.

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Abstract text
Background: The randomized controlled trial (RCT) is the most powerful research tool for evaluating health technologies. The number of RCT is rapidly increasing internationally. Despite the rapid increase in research in Japan, little is known about comprehensive information of RCTs conducted there.

Objectives: To assess the number and characteristics, and evaluate quality of RCTs conducted in Japan.

Methods: All RCTs conducted in Japan and published in 2010 were searched using the Japanese database (Japan Medical Abstract) and international databases (MEDLINE, EMBASE, CINAHL, and PsycINFO). Among 2,957 studies located, 1,034 studies were identified as RCTs by reviewing their abstracts and/or original papers. Characteristic of these RCTs were analyzed according to a subset of criteria. 10% of the RCTs identified were randomly selected and their quality was reviewed by using the risk of bias (van Tulder) scale.

Results: The total number of RCTs conducted in Japan and published in 2010 was 1,034. This number is very high compared with that estimated from the database of the Japan Primary Registries Network. 62.2% of them were published in Japanese domestic journals. While the proportion of head-to-head trials was 45.6%, that of placebo-control was 39.1%. The main type of interventions and designs were drug (49.7%) and parallel (76.2%), respectively. The main category of diseases was circulatory system (16.1%). The proportion of sample size less than 50 was 54.6%, followed by 50~100 (20.0%). The quality of the RCTs frequently did not meet the standards.

Conclusion: Although a considerable number of RCTs was conducted in Japan, the existing databases failed to capture them. Moreover, characteristics of RCTs are not corresponding to health care needs and their quality was insufficient to clarify the true effect of health interventions. Improvement and promotion of RCTs are urgently needed.
Authors
Yoneoka D1, Ota E1, Hisashige A1, Miyamoto K1, Nomura S1, Segawa M1, Kanda M1, Shibuya K1
1 Department of Global Health Policy, Graduate School of Medicine, The University of Tokyo , Japan
Presenting author and contact person
Presenting author: 
Erika Ota
Contact person Affiliation Country
Erika Ota (Contact this person) The university of Tokyo Japan