Key Points
- Three prior randomized trials including over two million adults in Denmark demonstrated that a variety of electronic message reminders, or “nudges”, to receive the influenza vaccination led to higher vaccination rates.
- This pre-specified pooled analysis evaluated the effect of this intervention among those with a history of recent acute myocardial infarction (AMI) compared to those with no AMI history, and found that nudges which highlighted the cardiovascular benefits of vaccination led to larger improvement in vaccine uptake in the AMI group, particular among those who had not been vaccinated in the prior season.
- Targeted electronic nudges may be a low-cost, highly scalable intervention to improve influenza vaccine rates among those with a history of AMI.
In addition to preventing infection, yearly influenza (flu) vaccination has also been shown to reduce the risk of cardiovascular events among those with established atherosclerotic cardiovascular disease. Despite these cardioprotective effects, uptake remains suboptimal. Three randomized trials in Denmark, NUDGE-FLU, NUDGE-FLU-2, and NUDGE-FLU Chronic found that email-based letter reminders, or electronic nudges, to receive the influenza vaccination improved vaccine rates overall. They also tested various framing of the nudges, including a nudge that highlighted the cardiovascular benefits of flu vaccination. However, whether these nudges had a differential impact on those with a history of acute myocardial infarction (AMI) – a group especially likely to benefit from the vaccine – remained uncertain.
On November 17th 2024, the results of “Electronic Nudges and Influenza Vaccination Among Patients With a History of Myocardial Infarction: Insights From 3 Nationwide Randomized Clinical Trials” were presented at AHA Scientific Sessions 2024 with simultaneous publication in the JAMA Cardiology. The purpose of this study was to determine which, if any, of the electronically delivered behavioral nudges preferentially improved influenza uptake among patients with a history of myocardial infarction.
The three randomized trials during the 2022-2023 and 2023-2024 flu seasons included a total of 2,146,124 individual randomization events. The mean age was 71 years, 52% were female and 2.8% had a history of AMI. Of patients with an AMI history, the most recent event was a STEMI in 26% of patients, NSTEMI in 50% of patients and unspecified in 24% of patients. Across all 3 trials, the receipt of any nudge letter increase vaccination rates similarly in those with and without a history of AMI compared to usual care (+1.81 percentage points vs +1.32 percentage points; p-value for interaction by AMI status = 0.09). However, they found that two specific electronic nudges led significantly greater improvements in vaccine uptake among those with a history of AMI compared to those without an AMI history: a nudge asking patients to commit to a time and place to obtain the vaccine (+3.04 percentage points vs + 1.52 percentage points; p-value for interaction by AMI status = 0.01) and a nudge highlighting the cardiovascular benefits of influenza vaccination (+3.91 percentage points vs. +2.03 percentage points; p-value for interaction = 0.002). Among those with an AMI, the nudge highlighting cardiovascular gain was even more effective among those who had not been vaccinated in the prior season (+13.7 percentage points vs. +1.48 percentage points; p-value for interaction by prior vaccine status <0.001).
Dr. Ankeet Bhatt, M.D., M.B.A., Sc.M., a cardiologist at Kaiser Permanente San Francisco Medical Center, a research scientist at the Kaiser Permanente Northern California Division of Research, and an adjunct professor at the Stanford University School of Medicine in Palo Alto, California, concluded: “The data suggest that cardiovascular focused messaging was effective across a broad population; this strategy should be considered as part of a suite of strategies to improve cardiovascular prevention and encourage flu vaccination among high-risk patients, including those with a history of heart attack. Notably, this strategy alone did not close all implementation gaps for flu vaccination. Other strategies in addition to messaging-based intervention need to be tested to fully close this important prevention gap in at-risk patients.”
- Bhatt AS, Johansen ND, Vaduganathan M, et al. Electronic Nudges and Influenza Vaccination Among Patients With a History of Myocardial Infarction: Insights From 3 Nationwide Randomized Clinical Trials. JAMA Cardiol.Published online November 17, 2024. doi:10.1001/jamacardio.2024.4648