A cross-sectional analysis of studies registered on ClinicalTrials.gov showed that despite a marked increase in COVID-19 studies, only 29.1% of them had the potential to result in a level 2 of the Oxford Centre for Evidence-Based Medicine (OCEBM) level of evidence, according to a research letter published in JAMA Internal Medicine.
The analysis included 1,551 studies registered between March 1, 2011, and May 19, 2020, that included the terms COVID-19, SARS-CoV-2, 2019-nCoV, 2019 novel coronavirus, or severe acute respiratory syndrome coronavirus 2. Researchers extracted all structured data fields, excluded withdrawn, suspended, terminated, or expanded-access studies, and categorised reported outcomes. The studies were graded using the 2011 OCEBM level of evidence framework to assess their expected strength of evidence.
From the 1,551 studies analysed, 911 (58.7%) were interventional, and 640 (41.3%) were observational studies. Frequently reported primary and secondary outcomes included mortality (526 [33.9%]), ventilation requirement (413 [26.6%]), and treatment complications (359 [23.1%]). Of the 1,551 studies, 451 (29.1%) could potentially yield OCEBM level 2 evidence, the highest level of individual study evidence.
The researchers say that although a few large multicentre trials may generate high-quality evidence, the large proportion of studies with an expected low level of evidence is concerning.