Electronic Nudge Letters to Increase Influenza Vaccination Uptake in Younger and Middle-Aged Individuals With Diabetes

Mats C Højbjerg Lassen; Niklas Dyrby Johansen; Muthiah Vaduganathan; Ankeet S Bhatt; Daniel Modin; Safia Chatur; Brian L Claggett; Kira Hyldekær Janstrup; Carsten Schade Larsen; Lykke Larsen; Lothar Wiese; Michael Dalager-Pedersen; Lars Køber; Scott D Solomon; Pradeesh Sivapalan; Jens Ulrik Stæhr Jensen; Cyril Jean-Marie Martel; Tyra Grove Krause; Tor Biering-Sørensen

doi:10.1016/j.jacadv.2024.101391

Electronic Nudge Letters to Increase Influenza Vaccination Uptake in Younger and Middle-Aged Individuals With Diabetes

JACC Adv. 2024 Nov 13;3(12):101391. doi: 10.1016/j.jacadv.2024.101391. eCollection 2024 Dec.

Authors

Mats C Højbjerg Lassen^{1

2

3}, Niklas Dyrby Johansen^{1

2

3}, Muthiah Vaduganathan^{3

4}, Ankeet S Bhatt^{5

6}, Daniel Modin^{1

2}, Safia Chatur³, Brian L Claggett³, Kira Hyldekær Janstrup^{1

2}, Carsten Schade Larsen⁷, Lykke Larsen⁸, Lothar Wiese⁹, Michael Dalager-Pedersen^{10

11}, Lars Køber^{12

13}, Scott D Solomon^{3

4}, Pradeesh Sivapalan^{12

14}, Jens Ulrik Stæhr Jensen^{12

14}, Cyril Jean-Marie Martel¹⁵, Tyra Grove Krause¹⁵, Tor Biering-Sørensen^{1

2

16}

Affiliations

¹ Department of Cardiology, Copenhagen University Hospital-Herlev and Gentofte, Copenhagen, Denmark.
² Center for Translational Cardiology and Pragmatic Randomized Trials, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
³ Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
⁴ Center for Cardiometabolic Implementation Science, Brigham and Women's Hospital, Boston, Massachusetts, USA.
⁵ Kaiser Permanente San Francisco Medical Center & Division of Research, San Francisco, California, USA.
⁶ Stanford University School of Medicine, Palo Alto, California, USA.
⁷ Department of Clinical Medicine-Department of Infectious Diseases, Aarhus University Hospital, Aarhus, Denmark.
⁸ Research Unit for Infectious Diseases, Odense University Hospital, Odense, Denmark.
⁹ Department of Infectious Diseases, Zealand University Hospital, Roskilde, Denmark.
¹⁰ Department of Infectious Diseases, Aalborg University Hospital, Aalborg, Denmark.
¹¹ Department of Clinical Medicine, Aalborg University Hospital, Aalborg, Denmark.
¹² Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
¹³ Department of Cardiology, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark.
¹⁴ Respiratory Medicine Section, Department of Medicine, Copenhagen University Hospital-Herlev and Gentofte, Copenhagen, Denmark.
¹⁵ Epidemiological Infectious Disease Preparedness, Statens Serum Institut, Copenhagen, Denmark.
¹⁶ Steno Diabetes Center Copenhagen, Copenhagen, Denmark.

Abstract

Background: Despite evidence demonstrating that influenza vaccination is associated with reduced risk of cardiovascular events and all-cause mortality in individuals with diabetes mellitus (DM), vaccine uptake remains suboptimal.

Objectives: The purpose of this study was to assess the effectiveness of electronically delivered nudges on influenza vaccine uptake according to the presence of DM status versus other chronic diseases.

Methods: NUDGE-FLU-CHRONIC was a nationwide, randomized, pragmatic implementation trial among younger and middle-aged (18-64 years) Danish citizens with chronic disease during the 2023/2024 influenza season. Participants were randomized in a 2.45:1:1:1:1:1:1 ratio to usual care (no electronic letter) or 1 of 6 different electronic nudge letters. The endpoint was receipt of a seasonal influenza vaccine on or before January 1, 2024.

Results: Of 299,881 participants, 57,666 (19.2%) had DM (median age: 51.6 years, 43.0% female). During the season, 43.0% of those with DM vs 34.6% of those without DM received the vaccine (P < 0.001). Any electronic letter vs usual care was highly effective in increasing vaccine uptake in participants with DM (45.6% vs 36.5%, difference: +9.1 percentage points [99.29% CI: 7.9-10.3], relative risk ratio: 1.42 [99.29% CI: 1.39-1.44]). However, DM status modified the effect of the interventions such that participants without DM at baseline experienced a greater relative gain than those with DM (37.3% vs 25.9%, difference: +12.3 percentage points [99.29% CI: 11.7-12.8], risk ratio: 1.47 [99.29% CI: 1.45-1.50]; P _interaction<0.001).

Conclusions: Electronic nudge letters effectively boosted vaccine uptake in individuals with DM and in individuals free of DM but with other chronic diseases, but the effect was lower among those with DM. Electronic nudges represent a low-cost and effective strategy to boost influenza vaccination rates in the DM population. (Nationwide Utilization of Danish Government Electronic Letter System for Increasing InFLUenza Vaccine Uptake Among Adults With Chronic Disease; NCT06030739).

Keywords: behavioral science; diabetes; implementation; influenza; nudging; randomized controlled trial; registry; vaccination.

Associated data

ClinicalTrials.gov/NCT06030739