Quality evaluation of randomized controlled trials of antipsychotic drugs for schizophrenia published in Chinese journals

BACKGROUND: The number of randomized-controlled trials (RCTs) originating from China is considerable. However, linguistic barriers and concerns regarding methodological rigor impede their inclusion in meta-analyses. METHODS: We searched 5 major Chinese databases for RCTs investigating antipsychotics in schizophrenia and contacted study authors to request information about reliability and methods of randomization and blinding using a semi-structured telephone interview and a specifically-designed online questionnaire in Chinese. RESULTS: Among 11,306 articles, 5117 purported RCTs were eligible. After 1232 telephone calls, 698 emails and 7126 letters, 378 authors responded on 349 studies (response rate: 6.9% of 5117 studies). Of those 29 (8.3%) employed randomization procedures and 35 (10.0%) blinding methods with low risk of bias. 125 (35.8%) used suboptimal randomization methods with high risk of bias. In 83 (23.8%) claimed RCTs clinicians chose the antipsychotic based on patients' symptoms and side effects indicating an observational instead of a randomized study design. For 13 (3.7%) modification of some specific outcome data was revealed and for 15 (4.3%) authors indicated that the study results are not reliable. For 57 (16.3%), authors answered "Not sure" to the direct question whether the trial was conducted in reality. There was no clear improvement of quality from 1998 to 2024. CONCLUSION: The main limitations of the study are the low response rate, which reduces representativeness, and that many authors answered they cannot recall which introduces uncertainty. From the answers received, it appears that the methodological quality of many RCTs on antipsychotics in schizophrenia published in Chinese language journals is limited despite initiatives of Chinese research institutions. Therefore, it is advisable that systematic reviewers seek direct confirmation of trial methodology before including Chinese studies in evidence synthesis and perform sensitivity analyses. Moreover, further training for Chinese clinical researchers and stricter quality assurance mechanisms by research institutions and publishers appear warranted.