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Am J Med. 1996 Mar;100(3):261-8.

The impact of disease severity on the informed consent process in clinical research.

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Bioethics Program, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland, USA.



To assess the efficacy of informed consent in subjects differing in disease severity, ranging from those with immediately life-threatening disease to healthy volunteers.


A total of 127 subjects, enrolled in four types of clinical research protocols, were tested. Subjects completed questionnaires before entry into the protocol, within 24 hours of signing the primary protocol's consent document, and 4 to 6 weeks after entry.


Healthy volunteers retained the most information about risks and side effects, and severely ill Phase I subjects retained the least (P <0.0001). Phase I and II subjects had the best long-term retention of information about procedures, whereas Phase III subjects and healthy volunteers retained the least (P <0.001). Information about the scientific purpose and confidentiality of data were retained best by symptom-free, Phase III subjects (P <0.05). Phase I subjects entered the study primarily for treatment purposes, and the consent document was rated less useful by subjects with more advanced disease (P <0.05).


Subjects with differing disease processes and illness severities focused on and retained different aspects of experimental protocols for dissimilar reasons. During the informed consent process, research staff should inquire of potential subjects' personal goals for participating in experimental protocols and develop means for ensuring subjects' understanding of the inherent risks and alternative interventions available.

[Indexed for MEDLINE]

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