Analysis of Registered Clinical Trials in The WHO International Clinical Trials Registry Platform, 2005-2019: A Cross-section Study (Preprint)

BACKGROUND Background: World health organization and the international committee of medical journal editors call for clinical trial registration before the start of the recruitment of participants. The registration promotes transparency and accessibility to all researchers and targeted patients globally. OBJECTIVE Objective: We conducted this research to explore the tendency and change of clinical trial registration among different classifications, in order to show the development of the registered clinical trials in the world. METHODS Methods: All clinical trials which had registered in the database of the International Clinical Trials Registry Platform (ICTRP) from 2005 to 2019 were collected as the database for analysis in this study. Developments of clinical trial registration were analyzed in terms of different registries, different regions, different income country classifications by covariance analysis for the difference in clinical trial registration and Cochran-Armitage Test for trend. The sample size enrolled was analyzed to explore whether there was any change in the scale of the clinical trials over time. RESULTS Results: Totally 205,228 clinical trials were registered in the ICTRP from 2005 to 2019. The numbers of clinical trial implementation annually increased as an exponential function (R2=0.83，t=10.45，P< .001). Almost 65% of clinical trials were performed in North American and East Asia & Pacific regions. There was a significant increasing trend in the numbers of clinical trial performance over time (F=184.85, P< .001). The numbers of clinical trial registration were different significantly between different income classifications of the country (F=90.84, P< .001). The sample sizes of the same Phases of clinical trials had no significant difference adjusted by income classification over time changes (F=0.57, P= .45). CONCLUSIONS Conclusions: The clinical trials were becoming flourishing in the world. Most of the clinical trials had performed in high and upper-middle-income countries, especially North American and East Asia & Pacific. And the lower-middle-income countries had a much faster-increasing trend in the clinical trial performance.