A numbers of randomized controlled trials reported in Chinese literature are not covered in MEDLINE

Article type
Zhang L1, Wang Y1, Lei JQ1, Yang KH1
1Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, Lanzhou, China
Background: More and more randomized controlled trials(RCTs) have been published in Chinese journals; However, Language restriction can be a problem for English-speaking countries collecting the relevant research data when they conduct systematic reviews.

Objectives: To the aim of this survey is to assess the number of reporting of RCTs in Chinese database comparing MEDLINE reporting Chinese literature number.

Methods: We conducted a comprehensive search using the term of ‘random*’, including MEDLINE from 1983 to 2012, and Chinese databases included Chinese BioMedical Literature (CBM) and China National Knowledge Internet (CNKI). We counted the number and calculated the proportion of RCTs in CBM and CNKI which are linked to MEDLINE.

Results: RCTs published in Chinese-based journal have been incorporated in Medline since 1983. Chinese-based journals included in MEDLINE increase annually (1% in 1983 vs. 10% in 2007), but are still a small proportion of the whole .152 237 RCTs were indexed in CBM and CNKI form 1978 to march of 2013. Of those, 5661 were linked to MEDLINE with less than 4% of RCTs indexed in CBM and CNKI not in MEDLINE. Percentage of Chinese language RCTs indexed in CBM and CNKI, 99% of RCTs recorded in CBM and CNKI were written in Chinese. We found that the maximum number is 547 RCTs published in Chinese journals in 2007.After 2007, number of RCTs published in Chinese-based journal but not incorporated in MEDLINE has increased dramatically. In 2012, 7388 articles were classified as RCTs in CBM and CNKI. Our survey revealed only 2512 articles (34%) were true RCTs, and others were not RCTs.

Conclusions: The number of RCTs published in Chinese journal increases year by year. The Chinese RCTs were also becoming valuable resources of systematic reviews. The great majority of Chinese RCTs are not incorporated in Medline. Local language literature database may not be neglected.