Two types of electronically delivered letter strategies – a letter highlighting potential cardiovascular benefits of influenza vaccination and a repeat reminder letter – increased flu shot uptake, compared with usual care alone, in a national study of seniors in Denmark.
And in a prespecified subanalysis focusing on older adults with cardiovascular disease, these two strategies were also effective in boosting vaccine uptake in those with or without CVD.
The findings are from the Nationwide Utilization of Danish Government Electronic Letter System for Increasing Influenza Vaccine Uptake (NUDGE-FLU) trial, which compared usual care alone with one of nine different electronic letter “behavioral nudge” strategies during the 2022-2023 flu season in people aged 65 years and older.
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Niklas Dyrby Johansen, MD, Hospital–Herlev and Gentofte and Copenhagen University, presented the main study findings in a late-breaking clinical trial session at the joint scientific sessions of the American College of Cardiology and the World Heart Federation, and the article was simultaneously published in The Lancet
The subanalysis in patients with CVD was published online March 5 in Circulation.
“Despite modest effect sizes, the results may have important implications when translated to a population level,” Dr. Dyrby Johansen concluded during his presentation. Still, the authors write, “the low-touch (no person-to-person interaction), inexpensive, and highly scalable nature of these electronic letters might have important population-level public health implications.”
They note that, among approximately 63 million Medicare beneficiaries in the United States, a 0.89–percentage point absolute increase in vaccination rate achieved through the most successful electronic letter in NUDGE-FLU, the one highlighting cardiovascular gain, would be expected to lead to 500,000 additional vaccinations and potentially prevent 7,849 illnesses, 4,395 medical visits, 714 hospitalizations, and 66 deaths each year.
Electronic letter systems similar to the one used in this trial are already in place in several European countries, including Sweden, Norway, and Ireland, the researchers note.
In countries such as the United States, where implementing a nationwide government electronic letter system might not be feasible, nudges could be done via email, text message, or other systems, but whether this would be as effective remains to be seen.
Commenting on the findings, David Cho, MD, UCLA Health and chair of the ACC Health Care Innovation Council, commended the researchers on engaging patients with more than a million separate nudges sent out during one flu season, and randomly assigning participants to 10 different types of nudges, calling it “impressive.”
“I think the concept that the nudge is to plant an idea that leads to an action is pretty much the basis of a lot of these health care interventions, which seems like a small way to have a big impact at outcome,” Dr. Cho noted. “The behavioral science aspects of the nudges are also fascinating to me personally, and I think to a lot of the cardiologists in the audience – about how you actually get people to act. I think it’s been a lifelong question for people in general, how do you get people to follow through on an action?”
“So I found the fact that secondary gain from a cardiovascular health standpoint, but also the repeated nudges were sort of simple ways that you could have people take ownership and get their flu vaccination,” he said.
“This is ACC, this is a cardiovascular conference, but the influence of vaccine is not just a primary care problem, it is also directly affecting cardiovascular disease,” Dr. Cho concluded.