open access

Vol 21, No 6 (2014)
Review paper
Published online: 2014-12-18
Get Citation

Clinical improvement of vasovagal syncope in the absence of specific therapies: The Seinfeld effect

Inderjeet Sahota, Robert Sheldon, Payam Pournazari
DOI: 10.5603/CJ.2014.0096
·
Cardiol J 2014;21(6):637-642.

open access

Vol 21, No 6 (2014)
Review articles
Published online: 2014-12-18

Abstract

Vasovagal syncope can persist for decades and recur sporadically but many patients appear to improve after being seen in specialty clinics. The absence of specific and proven effective therapy raises the possibility that this might be due to regression to the mean or to a placebo effect. However, analysis using the Poisson distribution indicates the extreme unlikeliness that regression to the mean is the explanation. A main cause of the placebo effect is expectancy. Subject expectancy is the influence of the subject’s anticipation of benefit on outcomes, and observer expectancy is the influence of investigator or physician attitudes and behavior on subject response. Ample data support the role of expectancy in outcomes of syncope patients. Moreover, expectancy can vary depending on the type of ineffective intervention. Interestingly, studies in which patients are blinded but the investigator is not show similar patient benefits compared with completely open label studies consistent with a strong observer expectancy effect due to physician-subject interaction. These results suggest the paramount importance of properly conducted randomized clinical trials in assessing biomedical interventions, and also illuminate the powerful potential of studies aimed at enhancing the expectancy effect on patient outcome.

Abstract

Vasovagal syncope can persist for decades and recur sporadically but many patients appear to improve after being seen in specialty clinics. The absence of specific and proven effective therapy raises the possibility that this might be due to regression to the mean or to a placebo effect. However, analysis using the Poisson distribution indicates the extreme unlikeliness that regression to the mean is the explanation. A main cause of the placebo effect is expectancy. Subject expectancy is the influence of the subject’s anticipation of benefit on outcomes, and observer expectancy is the influence of investigator or physician attitudes and behavior on subject response. Ample data support the role of expectancy in outcomes of syncope patients. Moreover, expectancy can vary depending on the type of ineffective intervention. Interestingly, studies in which patients are blinded but the investigator is not show similar patient benefits compared with completely open label studies consistent with a strong observer expectancy effect due to physician-subject interaction. These results suggest the paramount importance of properly conducted randomized clinical trials in assessing biomedical interventions, and also illuminate the powerful potential of studies aimed at enhancing the expectancy effect on patient outcome.

Get Citation

Keywords

vasovagal syncope, placebo, Poisson, natural history, expectancy

About this article
Title

Clinical improvement of vasovagal syncope in the absence of specific therapies: The Seinfeld effect

Journal

Cardiology Journal

Issue

Vol 21, No 6 (2014)

Article type

Review paper

Pages

637-642

Published online

2014-12-18

DOI

10.5603/CJ.2014.0096

Bibliographic record

Cardiol J 2014;21(6):637-642.

Keywords

vasovagal syncope
placebo
Poisson
natural history
expectancy

Authors

Inderjeet Sahota
Robert Sheldon
Payam Pournazari

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