Analysis of clinical and methodological characteristics of early COVID-19 treatment clinical trials: so much work, so many lost opportunities

Beatrice Mainoli, Tiago Machado, Gonçalo S. Duarte, Luísa Prada, Nilza Gonçalves, Joaquim J. Ferreira, João Costa

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)
16 Downloads (Pure)


Background: The COVID-19 pandemic continues to rage on, and clinical research has been promoted worldwide. We aimed to assess the clinical and methodological characteristics of treatment clinical trials that have been set forth as an early response to the COVID-19 pandemic. Methods: First, we reviewed all registered clinical trials on COVID-19. The World Health Organization International Trials Registry Platform and national trial registries were searched for COVID-19 trials through April 19th, 2020. For each record, independent researchers extracted interventions, participants, and methodological characteristics. Second, on September 14th, 2020 we evaluated the recruitment status and availability of the results of COVID-19 treatment trials previously identified. Results: In April 2020, a total of 580 trials evaluating COVID-19 treatment were registered. Reporting quality was poor (core participant information was missing in 24.1 to 92.7%). Between 54.0 and 93.8% of the trials did not plan to include older people or those with a higher baseline risk. Most studies were randomised (67.9%), single-centre (58.3%), non-industry-funded (81.1%), to be conducted in China (47.6%), with a median duration of 184 days and a median sample size of 100 participants. Core endpoints (mortality, clinical status, and hospitalization length) were planned to be assessed in 5.2 to 13.1% of the trials. Five months later, 66 trials (11.4%) were reported as “Completed”, and only 46 (7.9%) had public results available. One hundred forty-four of 580 trials (24.8%) either had the status “Not yet recruiting” or “Suspended”, and 18 (3.1%) trials were prematurely stopped (“Terminated” or “Withdrawn”) The number of completed trials and trials with results are much lower than anticipated, considering the planned follow-up. Conclusions: Our results raise concerns about the success of the initial global research effort on COVID-19 treatment. The clinical and methodological characteristics of early COVID-19 treatment trials limit their capability to produce clear answers to critical questions in the shortest possible time.

Original languageEnglish
Article number42
Pages (from-to)1-10
Number of pages10
JournalBMC Medical Research Methodology
Issue number1
Early online date26 Feb 2021
Publication statusPublished - Dec 2021


  • Clinical endpoints
  • Clinical trials
  • COVID-19
  • Meta-research
  • Trial methodology


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