Inability to obtain deferred consent due to early death in emergency research: effect on validity of clinical trial results.
OBJECTIVE
To illustrate the impact on the validity of trial results due to excluding patients from a randomized controlled trial for whom no deferred consent could be obtained after randomization because study procedures had already been finished.


METHODS
The unadjusted and adjusted primary outcome measures of a recent randomized controlled multicentre study in the field of intensive care medicine were compared, including (n = 348) or excluding (n = 289) patients with missing deferred consent.


RESULTS
Thirty-nine patients (11%) died early, before the patient or his/her proxy could be approached and consent be obtained. In another 20 patients (6%), it was not possible to inform proxies and ask consent within the period of study procedures. A significant treatment effect (p = 0.006) in the adjusted analysis became non-significant (p = 0.35) when the patients with missing deferred consent were excluded.


CONCLUSIONS
Exclusion of patients without obtained deferred consent can reduce statistical power, introduce selection bias, make randomization asymmetrical, decrease external validity and thereby jeopardize study results. This may have implications for emergency research in various disciplines.
Jansen
Tim C
TC
Department of Intensive Care, Erasmus MC University Medical Center, CA, Rotterdam, The Netherlands.
Bakker
Jan
J
Kompanje
Erwin J O
EJ
D000368:Aged; D035843:Biomedical Research; D003643:Death; D004635:Emergency Medicine; D005260:Female; D006801:Humans; D007258:Informed Consent; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D018579:Patient Selection; D015203:Reproducibility of Results