Effective or ineffective: Attribute framing and the human papillomavirus (HPV) vaccine

https://doi.org/10.1016/j.pec.2010.08.014Get rights and content

Abstract

Objective

To experimentally test whether presenting logically equivalent, but differently valenced effectiveness information (i.e. attribute framing) affects perceived effectiveness of the human papillomavirus (HPV) vaccine, vaccine-related intentions and policy opinions.

Methods

A survey-based experiment (N = 334) was fielded in August and September 2007 as part of a larger ongoing web-enabled monthly survey, the Annenberg National Health Communication Survey. Participants were randomly assigned to read a short passage about the HPV vaccine that framed vaccine effectiveness information in one of five ways. Afterward, they rated the vaccine and related opinion questions. Main statistical methods included ANOVA and t-tests.

Results

On average, respondents exposed to positive framing (70% effective) rated the HPV vaccine as more effective and were more supportive of vaccine mandate policy than those exposed to the negative frame (30% ineffective) or the control frame. Mixed valence frames showed some evidence for order effects; phrasing that ended by emphasizing vaccine ineffectiveness showed similar vaccine ratings to the negative frame.

Conclusion

The experiment finds that logically equivalent information about vaccine effectiveness not only influences perceived effectiveness, but can in some cases influence support for policies mandating vaccine use.

Practice implications

These framing effects should be considered when designing messages.

Introduction

The media, health professionals and social contacts often play a role in raising awareness about health issues. This is particularly true when the health issue is unfamiliar. In June 2006, Merck launched a first of a kind human papillomavirus (HPV) vaccine into the U.S. market for girls and women aged 9–26 [1]. Clinical trial results suggested that the Merck vaccine (Gardasil) protected against two HPV strains (18 and 16) that account for roughly 70% of cervical cancers and two other HPV strains (6 and 11) linked to 90% of genital warts.

Despite the fact that HPV is thought to be the most common sexually transmitted infection in the U.S., prior to the media coverage surrounding the new vaccine, few people in the U.S. or in other countries were familiar with the HPV virus, its status as a sexually transmitted disease or its role in causing cervical cancer [2], [3]. Even so, physicians, parents and adolescents were generally accepting of the vaccine and interested in obtaining more information about HPV [4], [5].

In light of the HPV vaccine's potential to prevent serious health problems like cervical cancer and genital warts, a number of measures to facilitate vaccine adoption were initially proposed by the U.S. public health and medical community, including securing endorsements from key professional organizations, conducting educational campaigns, covering the cost of the vaccination, and perhaps most controversial, legislating mandatory vaccination of eligible school girls.

The HPV vaccine's novelty combined with its planned indication for girls and the fact that it was for a sexually transmitted disease helped to generate controversy and spur media coverage even before the vaccine's release. The controversy has intensified since the vaccine's approval, particularly as states moved to put in place mandatory vaccination policies and opponents raised concerns about political improprieties, the impact on teen promiscuity and the long-term safety and effectiveness of the vaccine [6]. Battles over vaccine mandates and questions about vaccine safety and effectiveness are recurring themes in the history of vaccination policy in the U.S. [7].

Studies that have looked at vaccine acceptance indicate that perceived vaccine effectiveness is a fundamental consideration. This paper focuses specifically on whether the way in which equivalent effectiveness information is presented can result in different perceptions of HPV vaccine effectiveness and what implications that has for opinion about the vaccine and related outcomes, including beliefs about policy.

Early research into HPV vaccine acceptance showed adolescent women were sensitive to vaccine efficacy, along with physician endorsement and cost [8]. Perhaps unsurprisingly, people prefer more efficacious vaccines to those with lower efficacy rates [9]. A more recent review of 28 U.S. HPV vaccine acceptance studies confirms these earlier findings about effectiveness and cost [10].

To gain approval to market a vaccine, companies must conduct studies to show vaccine safety and efficacy. Consequently, a vaccine enters the U.S. market with some empirically determined efficacy or efficacy range based on one or more studies. However, even when there is one particular agreed upon efficacy figure, the same efficacy information can be framed in different ways.

Generally speaking, vaccine efficacy information can be verbal or quantitative and can be presented using fairly general or specific language. Information may focus on certain strains of a disease or it may highlight vaccine ability or inability to protect against the entire disease constellation. For instance, a vaccine could protect fully against several strains of the flu or some HIV clades or strains, but may not confer full protection against the flu or AIDS. Although commonly thought of as a single disease, many viral infections like HIV/AIDS and the flu can be caused by a number of different types of viral strains. Similarly, a number of high-risk strains of HPV can cause cervical cancer and genital warts. In this case, the Merck vaccine targets four specific strains (6, 11, 16 and 18) that account for a majority of, but not all, cervical cancer and genital wart cases.

Given the essential role that perceived effectiveness plays when it comes to medical treatments and preventative measures, it should not be surprising to find that news coverage of HPV vaccination often includes information that describes vaccine efficacy. HPV-related content analyses have been conducted with the goal of describing what kinds of information the media is conveying to the public about HPV [11].

A content analysis of media coverage of the HPV vaccine prior to its approval found that 20 (80%) of the articles reviewed did provide efficacy information about the vaccine [12]. However, this information varied. About half of the articles gave vague descriptors like “successful” and “effective” to describe the vaccine, while the other half included percentages. A subsequent content analysis that included the time period in which the vaccine was introduced onto the market found 95% of news included HPV vaccine efficacy information [13].

In sum, vaccine effectiveness plays a crucial role in vaccine acceptability, yet the same vaccine efficacy information can be conveyed to the public in different ways. Further, HPV vaccine effectiveness has been covered and communicated in the news in different ways.

Framing studies suggest that the way in which logically equivalent information is presented can impact health preferences and behavior [14], [15], [16], [17]. Much of the framing literature in the field traces its theoretical underpinnings to Kahneman and Tversky's Prospect Theory [18], [19]. Kahneman and Tversky were able to show when information is presented in certain ways, people systematically opt for a statistically less advantageous payout structure or respond to one presentation of logically equivalent information over another. People make inferences based on the context in which choices are presented, such as the way in which information is framed. They also bring their own individual predispositions to bear on the information.

In their seminal article, Levin, et al. distinguish among three types of frames – risky choice frames, goal frames and attribute or valence frames [17]. In the realm of health communication, researchers have often applied Prospect Theory to craft messages based on attaining or failing to attain a goal related to health prevention and detection behaviors [14], [20]. That type of framing is goal or gain-loss framing. When a particular aspect or characteristic of something is described such that the positive aspect or its formally equivalent negative is highlighted, it is an example of what Levin et al. label “attribute framing” [17]. Also described in the literature as “outcome salience” or “valence framing”, attribute framing tends to result in people being more amenable toward the object or treatment when it is framed positively.

In the health domain, attribute frames can describe efficacy rates, side effects and other outcomes for surgical treatments, vaccines, contraceptives, diagnostics, or medications. If a particular frame is included as part of a communication, it may intentionally or unwittingly affect perceived treatment efficacy and impact people's beliefs about personally using the health product or what kinds of policies should be associated with it. It may also impact beliefs about what policies should be put in place regarding the health product or likelihood of a person endorsing use of the technology. For instance, when students read that a condom had a “90% success rate” against HIV transmission, 86% said the government should be allowed to advertise the condom as “an effective method for reducing the risk of AIDS” and 85% said they would use it or encourage their partner to use it [21]. However, when the condom was described as having a 10% failure rate, the support for government advertising was 61% and only 63% of people said they would use or recommend it.

An efficacy message can also be framed based on either success or failure to protect against a disease. For example, a vaccine might be portrayed as “effective against strains that account for 70% of cases of a disease” or “ineffective against strains that account for 30% of cases.” The emphasis is either on vaccination efficacy, or its flip side, vaccine limitations. In fact, it has been widely reported that the HPV vaccine is 70% effective [22]. Occasionally, media reports have just presented percentages related to the vaccine's inability to protect against strains that cause 30% of cervical cancers [23]. Mixed frames that include both figures are not uncommon in news articles [24], [25]. Government sources, such as the Centers for Disease Control & Prevention, have also utilized mixed frames, including negative frames [1]. Research suggests it is possible that this kind of coverage may influence perceptions of the HPV vaccine.

Positively framed information regarding safety (90% chance of no side effects versus 10% chance of side effects) for a hypothetical infant vaccine was associated with more positive attitudes toward vaccination and combined intention to either seek more information or vaccinate [26]. Others have found similar framing effects for vaccinations [27]. When O’Connor, Pennie and Dales framed vaccine information positively (based on percentages and ratios of people remaining free of the flu and flu shot side effects), it resulted in more positive perceptions of the vaccine and its side effects. Furthermore, the expectations were more accurate compared to objective criteria. However, these perceptions did not translate into a difference in vaccine adoption. On the other hand, those who saw the positively framed information and did opt for vaccination reported fewer post-vaccination side effects and less work absenteeism. Thus, research finds that attribute framing can impact vaccine attitudes and in some circumstances may impact prevention-related policy support and vaccination-related intentions and behavior.

In sum, vaccine effectiveness plays a crucial role in vaccine acceptability, yet the same vaccine efficacy information can be conveyed to the public in different ways. Further, HPV vaccine effectiveness has been covered and communicated in the news in different ways. The theory surrounding attribute framing strongly suggests that the way in which vaccine effectiveness is framed can affect perceived HPV vaccine effectiveness specifically, and vaccine support more generally. For these reasons, it is worth asking whether the manner in which essentially equivalent effectiveness information is framed affects perceptions of vaccine effectiveness, and more broadly, support for vaccination and vaccine-related policies.

Based on literature regarding attribute frames, it was expected that when participants were asked to rate the vaccine, the group that saw the positive attribute frame for vaccine effectiveness would view the vaccine more favorably than the group that saw the negative attribute frame. Therefore, it was hypothesized that attribute framing would result in differences in vaccine ratings across conditions. Specifically, the positive attribute frame would result in higher mean rating of HPV vaccine effectiveness than the negative attribute frame.

A control condition allows for the examination of whether the positive attribute and negative attribute conditions not only resulted in differences in perceived effectiveness, but also whether they differed from a baseline control [28]. Few studies of attribute frames in the health arena have included a control condition [15]. The choice of a no effectiveness information control makes sense not only from a theoretical perspective, but also is justified from a more applied perspective. Prior content analyses had found that while a large majority included effectiveness information for the HPV vaccine, not all articles did [12], [13]. For these reasons, the experimental design included a control condition that presented the same background information shown in the other conditions, but excluded the effectiveness frame. It was expected that the positive attribute frame would result in a higher perceived effectiveness than the control condition and that the negative attribute frame would result in lower perceived effectiveness than the control condition.

Additionally, two mixed conditions were included because media coverage and official sources contained both the positive and the negative attribute frames in the same communication or news story. Therefore, it was considered important from an applied standpoint to explore the impact of having mixed messages. The mixed conditions were also included as a control for the positive and negative attribute frames in order to cover all valid logical combinations regarding the attribution frames in the experiment. The experiment was designed to counterbalance order in the mixed frames. If attribute frames trigger similarly valenced associations, mixed frames might dampen or altogether attenuate framing effects compared to purely positive or negative frames, depending on whether the affective associations triggered by the mixed frames are relatively balanced or if one affective dimension looms larger than the other.

The incorporation of mixed frames raises two questions. First, does the order of valenced frames matter? And second, do mixed frames produce results that differ from positive frames, negative frames or a control condition? Studies that include counterbalanced mixed frames have tended to conclude that there was no effect based on the order in which information was presented [29], [30], [31].

Results for combined mixed frames often have fallen between purely positive and negative frames. Yet, they also have produced conflicting findings as to whether the mixed frames were significantly different from negative frames, positive frames or neither. McNeil et al. found evidence for alignment with negative frames, and in one case, differences by gender [29]. By contrast, O’Connor et al. [30] and O’Connor [31] concluded that mixed frames were significantly different from negative, but not positive frames in the context of mortality versus survival framing. Thus, the question of directionality for mixed frames remains open.

Based on Levin et al.’s “valence consistent” shift hypothesis and Linville et al.’s finding with regard to condom recommendation, it was hypothesized that presenting purely positive frames for effectiveness would not only result in higher vaccine ratings related to that attribute, but also might influence more distal associations and affect beliefs, attitudes and intentions in such a way that the positive condition would result in more favorable beliefs and attitudes, and greater support for vaccination compared to the negative frame condition [17], [21].

Consequently, it was expected that compared with those who saw the negative attribute frame, people who read the positive frame would perceive the vaccine to be more effective in preventing cervical cancer and also would be more favorable in their attitude toward vaccination as a strategy to prevent cervical cancer. Additionally, positive frames would lead respondents to be more favorable toward personal recommendation of the vaccine and to report a greater likelihood of voting for a hypothetical candidate who favored mandatory vaccination compared with the negative condition. In the Linville et al. study, framing effectiveness of condoms not only influenced personal intentions, but also opinion about whether the government should be allowed to advertise the condom as “an effective method for reducing the risk of AIDS” [21]. It was therefore hypothesized that compared to those who read the negative frame, people who saw the positive frame for HPV vaccine effectiveness would report more agreement with policies supportive of the vaccine.

Section snippets

Sample

A total of 334 respondents completed the experimental module in August (n = 171) and September (n = 163) 2007 as part of a larger ongoing web-enabled monthly survey, the Annenberg National Health Communication Survey (ANHCS). ANHCS panel participants are chosen using random-digit dialing; those who lack Internet service are provided access and hardware to enable their participation in the survey. Each month, ANHCS survey participants are selected from a previously established research panel

Framing effects’ influence on vaccine effectiveness ratings

The experimental framing resulted in HPV vaccine effectiveness ratings that are in line with what would be expected based on attribute framing theory. An omnibus test for main effects using analysis of variance (ANOVA) found differences in perceived effectiveness of the HPV vaccine by condition F(4, 323) = 5.91, p  .001, partial η2 = .068 (see Fig. 1). There were no significant differences in randomization across conditions based on the demographic variables and pre-stimulus questions.

Pure valence frames

t-Tests

Discussion

The way an issue is covered can provide a “set of interpretative packages that give meaning to an issue” [34]. Particularly when a technology is new and people may not have much personal experience with it, media's coverage of negative and positive attributes or risks and benefits of a technology can play a role in setting an affective tone and influencing impressions of it [35]. This study extends what has been a robust theoretical finding in the attribute framing literature to HPV

Conflict of interest statement

None declared.

Acknowledgments

This research was supported by the National Cancer Institute Center of Excellence in Cancer Communication Research Grant P20-CA095856. Its contents are solely the responsibility of the authors. The authors would like to thank Bruce W. Hardy, Michael Serazio, our anonymous reviewers and Center of Excellence in Cancer Communication Research colleagues for their helpful comments.

Contributions: All authors made substantial contributions to all of the following: (1) the conception and design of the

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