Fig. 4

A breakdown of trials in ClinicalTrials.gov included in final analyses. a The primary purpose of the trial; b A treatment-purpose trial is to evaluate one or more interventions for treating a disease, syndrome or condition; c Phase of investigation as defined by the US FDA; d For trials that do not involve drug or biologic products (e.g., behavioural interventions); e Primary disease or condition being studied in the trial. The terms of the conditions should follow the National Library of Medicine’s Medical Subject Headings (MeSH) where possible; f Trials studying non-rare disease(s)/condition(s); g Trials studying both rare and non-rare disease(s)/condition(s); h Number of rare disease(s)/condition(s) being studied in a trial. i Estimated prevalence from Orphanet; j The rare disease/condition has no prevalence data from Orphanet