Study factors associated with the incompletion of clinical trials that include pediatric patients: a retrospective analysis of the European Clinical Trials Database and a lesson from the European region

BACKGROUND: Incomplete clinical trials for pediatric drug development result in a lack of adequate scientific evidence for providing appropriate medication to pediatric populations; this is especially true for Japan. Thus, using the European Clinical Trials Database (EudraCT), this study aimed to identify the factors related to the study design and administration that lead to incompletion of clinical trials that included pediatric patients. METHODS: We focused on clinical trials that included patients under the age of 18 registered in the database, named as the European Clinical Trials Database between January 1, 2014, and December 31, 2018. Two groups of trials were identified: “all cases completed” and “not all cases completed,” reflecting whether they were completed in all participating countries/regions or not. To identify the factors of the occurrence of “not all cases completed,” a logistic regression analysis was performed to calculate the odds ratios and 95% confidence intervals. In total, 142 clinical trials (95 “all cases completed” and 47 “not all cases completed”) were analyzed. RESULTS: The logistic regression analysis showed the number of countries in which a clinical trial was conducted to be the only significant factor (odds ratio: 1.3; 95% confidence interval: 1.1-1.5); this was identified as the primary factor for the occurrence of “not all cases completed” in the clinical trials that included pediatric patients. CONCLUSION: Our findings suggest that the feasibility of clinical trials that include pediatric patients, such as whether the countries in which the trial is to be conducted are suitable, must be considered prior to the trial. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13063-021-05143-6.