How often do Australian government-funded interventional trials exclude adults with intellectual disability? A retrospective registry analysis of ANZCTR records, 2022-2024.

Authors

Andrea Kargodorian, Rebecca Christidis, Jenny Downs, Helen Leonard, Julian Trollor

Published in

BMJ open. Volume 16. Issue 10. Pages e119053. Oct 20, 2026. Epub Oct 20, 2026.

Abstract

To quantify the frequency and types of direct and indirect exclusion criteria affecting adults with intellectual disability in Australian government-funded interventional clinical trials and to examine variation in exclusion patterns by trial characteristics.
Retrospective analysis of trial records registered on the Australian New Zealand Clinical Trials Registry (ANZCTR).
All ANZCTR records for interventional trials funded by an Australian government source and registered between 1 January 2022 and 31 December 2024 were downloaded from the ANZCTR website. Eligibility criteria were extracted from free-text registry fields. Exclusion criteria were coded using an adapted framework distinguishing direct exclusions (ie, diagnosis, consent capacity, cognitive capacity) and indirect exclusions (ie, language, technology requirements, staff discretion).
Trials were excluded if they were phase 0, 1, 1/2 or 2, if the minimum participant age was >55 years or if the participant maximum age was <18 years. Of 857 records screened, 685 trials met inclusion criteria.
Over half of trials (53%) contained no direct or indirect exclusion codes. One-third (34.2%) contained at least one direct exclusion criterion, most commonly requirements related to consent capacity (17.2%). Exclusion based on diagnostic labels was seen in 13.1% of trials and 4.8% explicitly excluded participants with intellectual disability. Indirect exclusion criteria were present in 25% of trials, including English-language requirements (12.3%) and staff-discretion codes (9.2%). Patterns varied by health condition and intervention type: cancer and drug trials showed the highest overall exclusion rates, while large trials (≥400 participants) were least likely to have any exclusions but more likely than small trials to explicitly exclude intellectual disability.
A substantial minority of Australian government-funded trials potentially exclude people with intellectual disability through diagnostic labels, assumptions about capacity and indirect mechanisms. Trials excluding potential participants on the basis of unassessed cognitive or consent capacity are inconsistent with ethics guidance about individualised assessment and supported decision-making. Findings suggest significant room for improvement in eligibility design, such as ensuring justification for diagnostic and capacity-based exclusions, and the adoption of validated approaches to supporting participation of adults with intellectual disability.

PMID:
42901550
Bibliographic data and abstract were imported from PubMed on 22 Oct 2026.

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