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J Clin Epidemiol. 2006 Jun;59(6):608-14. Epub 2006 Mar 24.

A brief measure of perceived understanding of informed consent in a clinical trial was validated.

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Department of Veterans Affairs, Cooperative Studies Program Coordinating Center, 950 Campbell Avenue, West Haven, CT 06516, USA.



To develop and evaluate an Informed Consent Questionnaire (ICQ) for measuring self-reported perceived understanding of informed consent in a randomized clinical trial.


The study was embedded in a Department of Veterans Affairs randomized clinical trial of Gulf War veterans' illnesses (CSP#470). The trial was initiated in May 1999 at 20 hospitals and concluded in September 2001; 1,092 participants were enrolled and followed for 12 months. The reliability and validity sample included 1,086 participants evaluated at baseline, 906 at 3 months, 929 at 6 months, and 910 at 12 months. The psychometric evaluations included tests of acceptability (based on missing data, endorsement frequencies, and floor/ceiling effects), item reduction, internal consistency, and construct validity (based on Cronbach's alpha coefficients, item-total correlations, and principal components analysis).


The ICQ had >5% missing information on some questions at baseline, indicating poor acceptability prior to the initiation of the trial; however, the scale had good acceptability at each of the follow-up visits. Psychometric evaluation following standard item reduction techniques confirmed the reliability and validity of a four-item subscale of the ICQ (ICQ-4).


The ICQ-4 is a simple and psychometrically sound self-report measure of perceived understanding of informed consent.

[Indexed for MEDLINE]

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