the impact of narrative reports about vaccine adverse events on vaccination risk perception: a...

THE IMPACT OF NARRATIVE REPORTS ABOUT VACCINE ADVERSE EVENTS ON VACCINATION RISK PERCEPTION:A SIMULATION OF AN ONLINE PATIENT NETWORK

Frank Renkewitz, Cornelia Betsch, Niels Haase

University of Erfurt

Renkewitz, Betsch, & Haase,

Health Information and the Internet• Increasing number of people uses the Internet to obtain health

information (Fox & Jones, 2008, Kummervold et al., 2008)

• Recent trend: Web 2.0 applications / social media

▫ Social patient networks (patientslikeme.com, “PLM”)

▫ Promote interaction and provide user generated content

▫ Provide opportunity to… Share experiences with treatments and medications Find other patients matched on clinical or demographic characteristics Learn from aggregated data reports of other users

• An example…

SMDM 2012, Oslo


Simulated Social Network – PLMSMDM 2012, Oslo

• Pie-Chart on side effects:


Simulated Social Network – PLMSMDM 2012, Oslo

• “Individual patient evaluations” - Narrative reports:


Social Patient Networks SMDM 2012, Oslo

• Positive Evaluations (Frost et al. 2008, 2011; Wicks et al., 2010)

▫ Patients assess PLM as beneficial▫ Help in starting / stopping medication; changing dosages▫ Social support

• Problems:▫ Self-selected and non-representative sample of users

Relative frequency of reports about effective treatments and side-effects may be biased.

▫ Source of narrative descriptions of treatments and side effects → Narrative Bias.

• Narrative Bias (e.g., Betsch et al., 2010, 2011; Fagerlin et al., 2005):▫ Narratives affect judgments and decisions in the presence of

more reliable statistical information when the number of narratives is small when the sampling procedure is unknown


Research Question

• How does the information environment available in online patient networks affect risk perceptions and decisions regarding pharmaceuticals?

▫ Domain: Vaccination and vaccine adverse events (VAE)

SMDM 2012, Oslo


StudySMDM 2012, Oslo

• Online experiment▫ 458 participants (85% female, Mean age: 32, highly educated)

• Procedure:▫ Information on a hypothetical disease (“Dysomerie”)▫ Highly infectious, severe symptoms (fever, emesis, meningitis)▫ Recommendation to vaccinate▫ Statistical information on VAEs (WHO survey) – 20%▫ Further information from a patient network

• IVs▫ Disclaimer: “bias awareness” vs. control▫ Relative Frequency of VAEs: 5%, 35% or 85%

discounted?▫ Type of information: pie chart, narratives or both

• Design: 2 x 3 x 3 between-subjects; random assignment


StudySMDM 2012, Oslo

• DVs▫ Perceived risk of vaccinating (scroll bar)▫ Intention to vaccinate (7-point scale)


Results – Perceived Risk SMDM 2012, Oslo

Effect of relative frequency of VAEs:• summary statistics: r

= .27• narratives: r

= .44• both: r

= .48


SMDM 2012, OsloResults – Perceived Risk

Effect of relative frequency of VAEs:• bias awareness: r = .34• control: r = .46

Disclaimer effect:


Results – Intention SMDM 2012, Oslo

Effect of relative frequency of VAEs:• summary statistics: r =

-.14• narratives: r =

-.25• both: r =

-.35


SMDM 2012, OsloResults – Intention

Effect of relative frequency of VAEs:• bias awareness: r =

-.17• control: r =

-.33

Disclaimer effect:


Conclusion• Biased sampling in online patient networks has the potential to

affect risk perceptions and treatment decisions.• Narrative information had a stronger impact than summary

statistics.▫ Evidence for a narrative bias▫ This bias occurred even though the narratives were rather “frugal”.

• Highly selected samples were not discounted. • A bias-disclaimer may reduce the effect.

SMDM 2012, Oslo


Thank you!

SMDM 2012, Oslo

Conflicts of interest: none

Betsch, C., Renkewitz, F. & Haase, N. (in press). Medical Decision Making.


SMDM 2012, Oslo


DisclaimersSMDM 2012, Oslo

• Bias awareness:In contrast to results from clinical studies, the patient reports published here are not representative of the experiences of all people who have received the respective medical product. The authors independently registered at the Patientenportal.de and voluntarily reported their experiences without being asked to do so. Therefore, it is possible that a self-selection is present. The published reports represent only the authors’ individual perceptions.

• Control (taken from PLM):While there is much information learned from clinical trials, they do not fully reflect the way a medical product is used in real life. By completing these reports, you can help improve the outcomes and safety of patients by contributing real world safety data to drug manufacturers and regulators.


Dependent variables

Construct Scale type Wording

Risk Risk bar How risky do you think is the vaccination? 0 = not at all risky, 100 = very risky

Intention 7-point scaleIf you had the possibility to get vaccinated during the next week, what would you do? (1 = definitely not vaccinate, 7 = definitely vaccinate)

Subjective probability 7-point scale

What is the probability of vaccine-adverse events if you are getting the vaccination? (1 = almost zero, 2 = very low, 3 = low, 4 = moderate, 5 = high, 6 = very high, 7 = almost sure).

Severity 7-point scaleHow severe do you think the side-effects of the vaccination are? (1 = not severe; 7 = very severe).

the impact of narrative reports about vaccine adverse events on vaccination risk perception: a...

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