The answer is provided by FDA’s 2025 Drug Trials Snapshots Summary Report. The report covers 46 novel drug approvals and roughly 26,000 participants across pivotal trials, organized by therapeutic area rather than a single aggregate narrative. Half (23 out of 46) of these approvals were for the treatment of rare or orphan diseases (i.e., diseases affecting <200,000 individuals in the U.S.). For health economists, the clinical trial structure matters: the mix of age, sex, and U.S. versus non-U.S. enrollment directly shapes how we interpret external validity and equity considerations of the clinical trial.
Looking at the data by disease area, a few patterns stand out. Autoimmune, inflammatory, and lung disease programs skew older than several other categories, consistent with the epidemiology of conditions such as severe asthma, idiopathic pulmonary fibrosis, and bronchiectasis. In contrast, many oncology programs have a notably low share of U.S. trial participants, reflecting global development strategies and potentially widening gaps between U.S. practice patterns and trial populations. Infectious disease trials, by comparison, show relatively higher U.S. enrollment than may be expected; while sex balance varies predictably where indications are sex-specific (for example, vasomotor symptoms due to menopause) versus mixed.
While these summary statistics are interesting from an academic perspective, policymakers should recognize that “trial diversity” is not a single headline metric. Clinical trials should be representative of the populations impacted by the diseases and the distribution of clinical trial participants’ age, sex, geography, and disease context are highly informed by disease epidemiology. Nevertheless, these data provide a useful overview of the types of patients who participate in the clinical trials or drugs that have been approved by the FDA. You can read the whole report here.
