LAUSR

Clinical investigators working in non–English-speaking countries are more likely to report their studies in an international, English-language journal if the results are positive and tend to publish negative findings in their local languages,1 which can cause exaggerated or even false-positive associations if investigators of systematic reviews and meta-analyses do not identify and include all relevant studies written in a non-English language.2 Although language bias has been reported for randomized clinical trials (RCTs), it is incompletely clear whether there is any language bias specifically in Chinese-sponsored RCTs (CS-RCTs). In JAMA Network Open, Jia et al3 compared CS-RCTs published in English with those published in Chinese. Using a retrospective cohort study, the authors verified that CS-RCTs with positive results are more likely to be published in English and indexed in English bibliographic databases than those with negative results. Based on this finding, the authors suggested an effect of language and indexing bias on the evaluation of RCT-based clinical evidence and recommended removing language restrictions and actively searching for Chinese bibliographic databases to reduce the influence of these biases on systematic reviews and meta-analyses. Systematic reviews and meta-analyses of RCTs provide important evidence for informing decision-making in clinical practice and for identifying areas in which further research is needed. A principle of conducting systematic reviews is to comprehensively review all existing evidence, whereas most systematic reviews and meta-analyses only include RCTs published in English. As Jia et al3 suggested in their study, 60% of systematic reviews set a language restriction when searching English bibliographic databases, whereas only 3% searched at least 1 Chinese bibliographic database for clinical trials. Because the number of CS-RCTs is increasing rapidly, it is important to include Chinese CS-RCTs when conducting systematic reviews and meta-analyses. By searching at ClinicalTrials.gov for the clinical trials initiated and sponsored by an organization or a person in mainland China, we found that the number of CS-RCTs increased every year, and the total number of CS-RCTs reached 13 175 by February 18, 2020, 7.5 times of that by 2011 (Figure). Of note, the number of CS-RCTs published in