Abstract
BACKGROUND: Mental disorders are among the leading causes of the global health-related burden, and depression is one of the most disabling mental disorders. The emergence of the COVID-19 pandemic has created an environment where many determinants of mental health are exacerbated. Many studies have been registered and conducted over the past 16 years, but how to choose the proper design for depression clinical trials remains the main concern. This study aimed to characterize the current status of global depression clinical trials registered on ClinicalTrials.gov. METHODS: We examined all the trials registered on ClinicalTrials.gov from 2007 to 2021. RESULTS: Overall, 7623 depression clinical trials were identified for analysis. Of those trials, 6402 (83.98%) were intervention trials and 1212 (15.90%) were observational trials. The majority of intervention types were behavioral (35.2%) and drug (28.55%), with very few procedures, dietary supplements, and diagnostic test studies. In addition, 55.53% of trials enrolled <100 participants. The proportions of trials registered in North America were higher than on other continents. Furthermore, the trials that involved only females (12.6%) were more than only males (0.87%) from 2019 to 2021. CONCLUSION: Depression clinical trials registered on ClinicalTrials.gov were dominated by small sample size trials, and there is a lack of trials related to COVID-19. The choice of study design is crucial, and properly designed trials can help improve study efficiency and reduce the likelihood of study failure. Given the increased number of RCT trials, the trial quality is gradually improving over the years. In addition, depression trials concentrating on children and older adults need more scientific attention. Further studies related to COVID-19 are needed, given the great damage that causes to people's physical and mental health.