ABSTRACT NUMBER: ESOC2026A1398 BIAS RISK FROM TYPE OF CONSENT IN CLINICAL TRIALS: A POST-HOC SUBSTUDY FROM A RANDOMIZED CLINICAL TRIAL

Abstract Background and aims Informed consent is fundamental in clinical research but presents a challenge in acute trials where patients may have impaired decision-making capacity. Deferred consent is not approved worldwide. We investigated whether type-of-consent is associated with systematic differences in patient characteristics that potentially compromise the generalizability of the results. Methods The RESIST trial was a prehospital randomized clinical trial investigating the efficacy of remote ischemic conditioning in acute stroke. The study was approved as an acute study, and consent was waived in the prehospital phase. In this sub-study, patients were stratified by type-of-consent. Baseline characteristics and outcome measures were compared between groups. Results Of the 1,500 patients randomized prehospital, 902 (60.1%) were diagnosed with acute stroke, and the remaining had conditions mimicking stroke. Consent by a legal guardian at the hospital was used in 256 (28%) patients with stroke. Subjects unable to consent were significantly older (75 vs. 72), had more severe strokes (National Institute of Health Stroke Scale [NIHSS], 14 vs. 3), more had atrial fibrillation (21.9% vs. 13.2%) and prior myocardial infarction (10.2% vs. 6.2%), and worse functional outcomes compared to those able to give informed consent. In multivariable analysis, stroke severity, as measured by NIHSS (aOR: 1.27; 95%CI: 1.23-1.31), and diagnosis of intracerebral hemorrhage (aOR: 1.77; 95%CI: 1.11–2.84) were independently associated with the inability to provide informed consent. Conclusions Clinical stroke trials that only recruit participants able to provide informed consent may be subject to consent-related selection bias that limits generalizability. (ClinicalTrials.gov, NCT03481777) Conflict of interest MKM reports a research grant from the Novo Nordisk Foundation outside the submitted work. DG reported receiving speaker honorarium from Bristol-Myers Squibb and Pfizer outside the submitted work and receiving financial support for attending meetings and travel by Bayer outside this work, and participated in research outside the submitted work funded by Bayer, with funds paid to the institution where he is employed. CZS reports a grant from the Health Research Foundation of Central Denmark Region outside the submitted work. RAB reports receiving personal fees from Novo Nordisk and Pfizer outside the submitted work. The other authors declare no conflict of interest.