More than two-thirds of new drugs approved by FDA in 2024 were based on a single study
Laine BergesonToday at 8:53 a.m.
Public Health
More than two-thirds of new drugs approved by the US Food and Drug Administration (FDA) in 2024 were sanctioned based on findings from a single study, according to a new analysis that found that the number of studies used to grant approval has steadily declined since 2016.
The findings, published this week in PLOS One, also show a sharp rise in industry-sponsored studies, a decrease in studies sponsored by the National Institutes of Health (NIH), and delays in reporting study results to the public.
The decline in the number of studies coincided with implementation of the 21st Century Cures Act, which was signed into law in 2016 to accelerate the development of new medical products and drugs. Although the FDA could already approve a drug based on the strength of one well-designed trial, the law gave the agency greater flexibility to consider single trials.
Approval based on single study ‘concerning’
For the study, researchers led by a team from Stanford University analyzed 6,763 studies associated with new FDA drug approvals from January 1, 2016, through December 31, 2024, cataloging them based on the number of studies relied on for each approval, study sponsor, and the timing between study completion and public reporting of results.In 2016, the mean number of studies supporting an approval was 3.41. That number fell to 1.50 in 2022 and 1.39 in 2024. (The mean number of studies per approval in 2023 was 2.49, due to a single outlier based on nine trials. Excluding the outlier, the mean number for 2023 was 1.85.)
This downward trend was also evident in the proportion of approvals supported by multiple studies. In 2016, 59.1% of novel drugs were approved based on three or more trials. By 2024, that figure had fallen to 5.6%. That same year, 69.4% of medical products were approved based on a single study.
“Replication is a cornerstone of the scientific method,” senior author and Adjunct Professor of Medicine at Stanford University Robert Kaplan, PhD, says in a PLOS news release. “The growing practice of approving medications on the basis of a single trial is concerning, as it allows products to reach the market without independent confirmation of the findings.”
Industry-funded studies on the rise
In 2016, industry-funded studies accounted for 44.6% of the research associated with approvals, compared with 80.4% in 2024. Studies sponsored by the NIH or other government sources represented less than 3% of total study funding in most years during this period.The researchers also assessed the substantial delays in reporting study results to the public. The findings show that the average number of days between a study’s completion date and the results being made public rose from 682 in 2016 to 728 in 2023, with considerable variability in between.
“While there were periods of both extension and reduction in the time taken to post results, the average time remained consistently above one year for studies with available results throughout the observed years,” write the researchers.
As an observational study, the findings cannot show that the 21st Century Cures Act caused the decline. Shifts in the types of drugs being developed, evolving trial design standards, and changes in the broader drug development ecosystem may have contributed, the researchers note.
While the analysis doesn’t look at whether current practices increase risks for patients, the findings highlight the need for greater transparency and stronger regulations. “Moving forward, policies that bolster post-market surveillance, enforce timely and comprehensive trial result reporting, and support independent clinical research are crucial for maintaining the integrity of the drug approval process,” they conclude.