Mothers' Perceptions of their Daughters' Susceptibility to HPV-related Risk Factors: An Experimental Pretest Comparing Narrative and Statistical Risk Information

In the Netherlands, human papillomavirus (HPV) vaccination uptake is low (46%). In order to promote HPV vaccination acceptability among mothers of girls, the researchers developed a web-based, tailored intervention (described in the paper at Related Summaries, below). This study reports on an experimental pretest for the component of this intervention targeting mothers' perceptions of their daughters' susceptibility towards HPV-related risk factors; perceived susceptibility has been shown to be an important factor of preventive behaviour according to health theory (e.g., the Health Belief Model).

Research findings are mixed about the value of either using statistical or narrative risk information in affecting perceived susceptibility.

• Statistical risk information includes abstracts of numerical data and factual assertions (e.g., prevalence rates) about the probability of contracting a certain health-related outcome.
• A narrative consists of a personal experience of an event, such as somebody getting a disease. It has been suggested that narratives trigger the simulation heuristic, according to which the perceived likelihood of an event is based on the ease to picture the event mentally.

In addition to investigating the value of each of these types of information, the research explores: (i) whether the effects of risk information depend on the information being believed as more or less comprehensible, credible, and/or novel; and (ii) whether the effects of risk information are mediated by imaginability, elaboration, relevance, and defensive reactions.

The researchers used data from 375 mothers of girls-to-be invited to the HPV vaccination round in 2014, who were derived from the Dutch National Immunization Register. They were randomly assigned to one of four conditions in a 2 (statistical information: yes or no) × 2 (narrative information: yes or no) between-subjects factorial design. All participants received general information about HPV, cervical cancer, and the HPV vaccine. Next, mothers in the experimental conditions additionally received risk information (each about 300 words):

• The statistical message presented factual epidemiological information about the prevalence of HPV and cervical cancer among women and information about the reduction in cervical cancer cases to be expected if all girls were to obtain the HPV vaccine.
• The narrative message was based on a personal story derived from an internet health forum of a woman who had found out she had cervical cancer, caused years ago by an HPV infection. It was reported in the first person, because research has shown this to be more effective in influencing perceived susceptibility than the third person. "Anne" ended her story by noting: "With the HPV-vaccination that is available now, I sometimes can't help but wonder: 'what if I had gotten myself vaccinated against HPV 18 years ago...?'"

Mothers who received statistical information perceived their daughters' susceptibility towards HPV to be higher (mean (M) = 4.11, standard deviation (SD) = .10) than mothers who did not receive statistical information (M = 3.73, SD = .09). There was no main effect of narrative risk information on perceived daughters' susceptibility towards HPV, nor was there a significant interaction-effect between statistical and narrative information on perceived daughters' susceptibility towards HPV. The effect of statistical information on mothers' perceptions of their daughters' susceptibility towards HPV was not moderated by perceived comprehensibility, credibility, or novelty of the risk information, nor mediated by message-induced imaginability, elaboration, personal relevance, or defensive reactions.

Secondary analysis indicated that mothers could imagine their daughter contracting both HPV and cervical cancer less easily after reading the narrative compared to the statistics. The absence of an effect of narrative information may have been associated with difficulty for mothers to identify their adolescent daughter with the 30-year-old woman getting cervical cancer. For narrative risk information to be effective, it is important that one can identify herself with the narrative. Difficulties with mothers' identification of their daughter may also have been associated with the relatively young age at which the character had sex for the first time (i.e., 16 years old). Finally, mothers may not have been "transported" into the narrative enough.

In addition, the researchers found that statistical information was judged more personally relevant, which increased mothers' perceptions of their daughters' susceptibility towards HPV. This is in line with the Elaboration Likelihood Model, which suggests that message relevance increases active processing of messages, which in turn enhances message effectiveness if persuasive arguments are perceived as strong. Moreover, this implies that statistical messages should be designed in a way that is personally relevant to the message recipient. This can be done, for instance, by tailoring the message to the recipient.

Although mothers who received statistical information felt that their daughters were more susceptible towards HPV, this did not result in a higher HPV vaccination intention. An explanation comes from social cognitive models of health behaviour (e.g., the Health Belief Model and the Health Action Process Approach), which indicate that perceived daughters' susceptibility is not the sole determinant of mothers' intention to have their daughter vaccinated against HPV. Thus, in the web-based intervention promoting HPV vaccination acceptability, other relevant determinants of HPV-vaccination uptake were also targeted.

In conclusion, statistical risk information appeared most effective in increasing mothers' perceptions of their daughters' susceptibility towards HPV and was therefore included in the planned web-based, tailored intervention promoting HPV vaccination acceptability. Future research is recommended on (a) how to best present statistical risk information and (b) how to make narratives about HPV-related risks more effective.