Take about 300 folks who have hypertension (controlled and uncontrolled) but not receiving any intervention (drugs, diet, exercise) to reduce it. Half of them are randomly assigned to a control group that we follow. The other half are exposed to 3 DVDs displaying folks that look like them talking about their hypertension and how they handle it. Take medical office blood pressure readings on all folks at baseline, 3 months, and 6 to 9 months. Compare BP scores between the no-message control group and the persuasion message group. Here’s what you get.
Among patients with uncontrolled hypertension, reduction from baseline to 3 months favored the intervention group for both systolic (11.21 mm Hg [95% CI, 2.51 to 19.9 mm Hg]; P = 0.012) and diastolic (6.43 mm Hg [CI, 1.49 to 11.45 mm Hg]; P = 0.012) blood pressures. Similarly, blood pressure reduction in these patients from baseline to 6 to 9 months also favored the intervention group for systolic (6.43 mm Hg [CI, 1.41 to 11.45 mm Hg]; P = 0.012) and diastolic (4.22 mm Hg [CI, -1.08 to 9.53 mm Hg]; P = 0.119) blood pressures.
So, only among uncontrolled hypertensives, exposure to 3 DVDs featuring just folks talking about their experience with hypertension produces statistically significant changes in blood pressure. Expressed in Windowpane terms these differences are near Medium or about 38/62. Considering that this is a randomized field experiment, this effect size is meaningful, practical, easily observable to a careful viewer. The persuasive message of just folks talking about their experience produces an obvious difference.
How big is this difference compared to other interventions for hypertension?
We compared our findings with those from previous pharmaceutical, nonpharmaceutical, and behavioral hypertension treatment trials. According to data from the ALLHAT (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial), chlorthalidone, amlodipine, and lisinopril decreased systolic blood pressure by between 10.5 and 12.3 mm Hg and diastolic blood pressure by between 8.6 and 9.3 mm Hg over 5 years (18). Appel and colleagues (19) reported that an 8-week intervention to improve dietary behaviors of patients with hypertension led to decreases of 11.4 mm Hg in systolic blood pressure. In a systematic review of 11 studies of behavioral interventions (20), the Cochrane collaboration found that the mean reduction in systolic blood pressure for the intervention groups was -0.57 mm Hg (CI, -1.22 to 0.08 mm Hg) compared with the control groups. Thus, our intervention produced greater changes than many behavioral interventions and performed similarly to nonpharmaceutical and pharmaceutical interventions.
So, a persuasive message produced BP changes at least as large as any other scientifically verified intervention. Now, let’s analyze this field experiment.
1. Exactly what was the intervention? Realize that people knew they were enrolled in a study, gave consent, and also received an orienting educational session. They then watched the first DVD in a medical office. Later they received two different DVDs at different time periods, all featuring that just folks talking about their experience with hypertension.
Now, if someone tries to replicate this intervention by simply mailing 3 DVDs to people, I doubt they will obtain the same effect. It is necessary that people consent into this intervention for it to work. There is a psychology at work in this intervention that is fundamentally different from a pill. Minimally, you have to elicit an Internal Attribution among DVD participants that makes them take responsibility for seeking, receiving, and processing the persuasive message. The researchers estimated that participants spent about 90 minutes viewing the 3 DVDs, each running about 60 minutes. That is a huge amount of reception (90 minutes received from 180 minutes available) and will not occur unless participants have a personal commitment to getting the DVDs. If you’ve ever done a mass mailing (which is what this is) to a random sample of households, you know you won’t get more than 5-10% of the receivers to even realize they got your mailing.
If you are running a clinic, you’d need to replicate the credibility elements of this report to achieve similar outcomes. Recruit in your clinic. Have an Official wearing a white lab coat explain the program and participation. Make it sound scientific, important, and credible. Then do the mailings.
2. What was the persuasion play in the DVDs? This research team received a grant from the Robert Woods Johnson Foundation for this research. They developed culturally sensitive communication materials for their audience (African-Americans using a hospital in Alabama) based on, good grief, the Health Beliefs Model. Using the main elements from this disproven theory (threat, risk, benefits, and barriers), the researchers selected just folks from the population of regular hospital clients to tell their story. Researchers then edited the video material available to find key moments that demonstrated threat, risk, benefits, and barriers. (You can view some of these selected video moments here.)
Where to begin. HBM does not work. When anyone does an HBM intervention and they get congenial results it is not because of HBM, but because of something else, the Theory of Planned Behavior, most likely. The first video example displays a woman emotionally describing her desire to stay alive and healthy to watch her grandchildren grow up. What is this from a persuasion theory perspective? With HBM, it could be a threat (death), risk (hypertension), benefit (joy of grandkids), or a barrier, (healthy lifestyle is difficult). So, which is it?
One of the great plagues in health and safety persuasion clinical work is precisely this failure to understand and properly apply theory. It is exactly equivalent to giving a drug cocktail to people and finding a positive overall result but with no understanding of what in the cocktail worked with whom and under what conditions. Worse still, medical researchers doggedly persist in thinking that HBM is real and effective when it is not. Yes, this report shows positive results for DVD viewing among uncontrolled hypertensives. No, this report does not demonstrate any support for HBM, just a message cocktail of many possible persuasion principles.
3. What did people do to reduce uncontrolled hypertension? Hey, a near Medium effect on BP means these people seriously changed their behavior. This report does not specify what these people did. At one level some people may shrug it off with, “it worked!” but you really need to know what behavior change actually occurred. In other words, what were the TACTs that reduced BP? That would seem to be useful information.
This also ties back to the persuasion concepts mishmash noted just above at Point 2. The message contains many different persuasion plays and it appears that the receivers produced many different TACTs to achieve the positive BP change. This is bad science. We do not know which persuasion plays changed which TACTs and which plays didn’t work or which TACTs were not performed.
4. What’s the future research? It would be nice to see better control over the persuasion and communication theory. It would be nice to see better control and/or measurement of specific behaviors linked to hypertension reduction, the TACTs. It would be nice to target specific persuasion plays and principles, present them in a controlled experiment and see what works. Or you could just read the research literature more carefully and find this has already been done for you.
So. At some level of scientific knowledge, this research shows that you can send messages to people to change their voluntary behavior that improves their blood pressure as well as any other proven intervention.
Who would have guessed that?