The relative vaccine effectiveness of high-dose vs standard-dose influenza vaccines in preventing hospitalization and mortality: A meta-analysis of evidence from randomized trials.

OBJECTIVES: To summarize current evidence of high-dose influenza vaccine (HD-IV) vs standard-dose (SD-IV) regarding severe clinical outcomes. METHODS: A prespecified meta-analysis was conducted to assess relative vaccine effectiveness (rVE) of HD-IV vs SD-IV in reducing the rates of (1) pneumonia and influenza (P&I) hospitalization, (2) all hospitalizations, and (3) all-cause death in adults ≥ 65 years in randomized controlled trials. Pooled effect sizes were estimated using fixed-effects models with the inverse variance method. RESULTS: Five randomized trials were included encompassing 105,685 individuals. HD-IV vs SD-IV reduced P&I hospitalizations (rVE: 23.5 %, [95 %CI: 12.3 to 33.2]). HD-IV vs SD-IV also reduced rate of all-cause hospitalizations (rVE: 7.3 %, [95 %CI: 4.5 to 10.0]). No significant differences were observed in death rates (rVE = 1.6 % ([95 %CI: -2.0 to 5.0]) in HD-IV vs SD-IV. Sensitivity analyses omitting trials with participants sharing the same comorbidity, trials with ≥ 100 events, and random-effects models provided comparable estimates for all outcomes. CONCLUSIONS: HD-IV reduced the incidence of P&I and all-cause hospitalization vs SD-IV in adults ≥ 65 years in randomized trials, through no significant difference was observed in all-cause death rates. These findings, supported by evidence from several randomized studies, can benefit from replication in a fully powered, individually randomized trial.

Effects of high-dose versus standard-dose quadrivalent influenza vaccine among patients with diabetes: A post-hoc analysis of the DANFLU-1 trial.

AIM: High-dose quadrivalent influenza vaccine (QIV-HD) has been shown to be more effective than standard-dose (QIV-SD) in reducing influenza infection, but whether diabetes status affects relative vaccine effectiveness (rVE) is unknown. We aimed to assess rVE on change in glycated haemoglobin [HbA1c (∆HbA1c)], incident diabetes, total all-cause hospitalizations (first + recurrent), and a composite of all-cause mortality and hospitalization for pneumonia or influenza. METHODS: DANFLU-1 was a pragmatic, open-label trial randomizing adults (65-79 years) 1:1 to QIV-HD or QIV-SD during the 2021/22 influenza season. Cox proportional hazards regression was used to estimate rVE against incident diabetes and the composite endpoint, negative binomial regression to estimate rVE against all-cause hospitalizations, and ANCOVA when assessing rVE against ∆HbA1c. RESULTS: Of the 12 477 participants, 1162 (9.3%) had diabetes at baseline. QIV-HD, compared with QIV-SD, was associated with a reduction in the rate of all-cause hospitalizations irrespective of diabetes [overall: 647 vs. 742 events, incidence rate ratio (IRR): 0.87, 95% CI (0.76-0.99); diabetes: 93 vs. 118 events, IRR: 0.80, 95% CI (0.55-1.15); without diabetes: 554 vs. 624 events, IRR: 0.88, 95% CI (0.76-1.01), pinteraction = 0.62]. Among those with diabetes, QIV-HD was associated with a lower risk of the composite outcome [2 vs. 11 events, HR: 0.18, 95% CI (0.04-0.83)] but had no effect on ∆HbA1c; QIV-HD adjusted mean difference: ∆ + 0.2 mmol/mol, 95% CI (-0.9 to 1.2). QIV-HD did not affect the risk of incident diabetes [HR 1.18, 95% CI (0.94-1.47)]. CONCLUSIONS: In this post-hoc analysis, QIV-HD versus QIV-SD was associated with an increased rVE against the composite of all-cause death and hospitalization for pneumonia/influenza, and the all-cause hospitalization rate irrespective of diabetes status.

Clinical Outcomes With Electronic Nudges to Increase Influenza Vaccination : A Prespecified Analysis of a Nationwide, Pragmatic, Registry-Based, Randomized Implementation Trial.

BACKGROUND: In the NUDGE-FLU (Nationwide Utilization of Danish Government Electronic letter system for increasing inFLUenza vaccine uptake) trial, electronic letters incorporating cardiovascular (CV) gain-framing and repeated messaging increased influenza vaccination by approximately 1 percentage point. OBJECTIVE: To evaluate the effects of the successful nudging interventions on downstream clinical outcomes. DESIGN: Prespecified exploratory analysis of a nationwide randomized implementation trial. (ClinicalTrials.gov: NCT05542004). SETTING: The 2022 to 2023 influenza season. PARTICIPANTS: 964 870 Danish citizens aged 65 years or older. INTERVENTION: Usual care or 9 different electronically delivered behavioral nudging letters. MEASUREMENTS: Cardiovascular, respiratory, and other clinical end points during follow-up from intervention delivery (16 September 2022) through 31 May 2023. RESULTS: The analysis set included 691 820 participants. Hospitalization for pneumonia or influenza occurred in 3354 of 346 327 (1.0%) participants in the usual care group, 396 of 38 586 (1.0%) in the CV gain-framing group (hazard ratio [HR], 1.06 [95% CI, 0.95 to 1.18]; versus usual care), and 403 of 38 231 (1.1%) in the repeated letter group (HR, 1.09 [CI, 0.98 to 1.21]; versus usual care). In the usual care group, 44 682 (12.9%) participants were hospitalized for any cause, compared with 5002 (13.0%) in the CV gain-framing group (HR, 1.00 [CI, 0.97 to 1.03]; versus usual care) and 4965 (13.0%) in the repeated letter group (HR, 1.01 [CI, 0.98 to 1.04]; versus usual care). A total of 6341 (1.8%) participants died in the usual care group, compared with 721 (1.9%) in the CV gain-framing group (HR, 1.02 [CI, 0.94 to 1.10]; versus usual care) and 646 (1.7%) in the repeated letter group (HR, 0.92 [CI, 0.85 to 1.00]; versus usual care). LIMITATION: Prespecified but exploratory analysis, potential misclassification of events in routinely collected registry data, and results may not be generalizable to other health systems or countries with other racial compositions and/or cultural or societal norms. CONCLUSION: In a prespecified exploratory analysis, modest increases in influenza vaccination rates seen with electronic nudges did not translate into observable improvements in clinical outcomes. Seasonal influenza vaccination should remain strongly recommended. PRIMARY FUNDING SOURCE: Sanofi.

Rationale and design of NUDGE-FLU-CHRONIC and NUDGE-FLU-2: Two nationwide randomized trials of electronic nudges to increase influenza vaccination among patients with chronic diseases and older adults during the 2023/2024 influenza season.

BACKGROUND: Yearly influenza vaccination is strongly recommended for older adults and patients with chronic diseases including cardiovascular disease (CVD); however, vaccination rates remain suboptimal, particularly among younger patients. Electronic letters incorporating behavioral nudges are highly scalable public health interventions which can potentially increase vaccination, but further research is needed to determine the most effective strategies and to assess effectiveness across different populations. The purpose of NUDGE-FLU-CHRONIC and NUDGE-FLU-2 are to evaluate the effectiveness of electronic nudges delivered via the Danish governmental electronic letter system in increasing influenza vaccination among patients with chronic diseases and older adults, respectively. METHODS: Both trials are designed as pragmatic randomized implementation trials enrolling all Danish citizens in their respective target groups and conducted during the 2023/2024 influenza season. NUDGE-FLU-CHRONIC enrolls patients aged 18-64 years with chronic diseases. NUDGE-FLU-2 builds upon the NUDGE-FLU trial conducted in 2022/2023 and aims to expand the evidence by testing both previously successful and new nudges among adults ≥65 years during a subsequent influenza season. Persons with exemptions from the electronic letter system are excluded from both trials. In both trials, participants are randomized in a 2.45:1:1:1:1:1:1 ratio to either receive no electronic letter (usual care) or to receive one of 6 different behaviorally informed electronic letters. NUDGE-FLU-CHRONIC has randomized 299,881 participants with intervention letters delivered on September 24, 2023, while NUDGE-FLU-2 has randomized 881,373 participants and delivered intervention letters on September 13, 2023. Follow-up is currently ongoing. In both trials, the primary endpoint is receipt of influenza vaccination on or before January 1, 2024, and the secondary endpoint is time to vaccination. Clinical outcomes including respiratory and cardiovascular hospitalizations, all-cause hospitalization, and mortality are included as prespecified exploratory endpoints. Prespecified individual-level pooled analyses will be conducted across NUDGE-FLU, NUDGE-FLU-CHRONIC, and NUDGE-FLU-2. DISCUSSION: NUDGE-FLU-CHRONIC is the first nationwide randomized trial of electronic nudges to increase influenza vaccination conducted among 18-64-year-old high-risk patients with chronic diseases. NUDGE-FLU-2 will provide further evidence on the effectiveness of electronic nudges among older adults ≥65 years. Collectively, the NUDGE-FLU trials will provide an extensive evidence base for future public health communications. TRIAL REGISTRATION: NUDGE-FLU-CHRONIC: Clinicaltrials.gov: NCT06030739, registered September 11, 2023, https://clinicaltrials.gov/study/NCT06030739. NUDGE-FLU-2: Clinicaltrials.gov: NCT06030726, registered September 11, 2023, https://clinicaltrials.gov/study/NCT06030726.

Effectiveness of high-dose versus standard-dose quadrivalent influenza vaccine against recurrent hospitalizations and mortality in relation to influenza circulation: A post-hoc analysis of the DANFLU-1 randomized clinical trial.

OBJECTIVES: To evaluate the relative effectiveness of high-dose quadrivalent influenza vaccine (QIV-HD) versus standard-dose quadrivalent influenza vaccine (QIV-SD) against recurrent hospitalizations and its potential variation in relation to influenza circulation. METHODS: We did a post-hoc analysis of a pragmatic, open-label, randomized trial of QIV-HD versus QIV-SD performed during the 2021-2022 influenza season among adults aged 65-79 years. Participants were enrolled in October 2021-November, 2021 and followed for outcomes from 14 days postvaccination until 31 May, 2022. We investigated the following outcomes: Hospitalizations for pneumonia or influenza, respiratory hospitalizations, cardio-respiratory hospitalizations, cardiovascular hospitalizations, all-cause hospitalizations, and all-cause death. Outcomes were analysed as recurrent events. Cumulative numbers of events were assessed weekly. Cumulative relative effectiveness estimates were calculated and descriptively compared with influenza circulation. The trial is registered at Clinicaltrials.gov: NCT05048589. RESULTS: Among 12,477 randomly assigned participants, receiving QIV-HD was associated with lower incidence rates of hospitalizations for pneumonia or influenza (10 vs. 33 events, incidence rate ratio [IRR] 0.30 [95% CI, 0.14-0.64]; p 0.002) and all-cause hospitalizations (647 vs. 742 events, IRR 0.87 [95% CI, 0.76-0.99]; p 0.032) compared with QIV-SD. Trends favouring QIV-HD were consistently observed over time including in the period before active influenza transmission; i.e. while the first week with a ≥10% influenza test positivity rate was calendar week 10, 2022, the first statistically significant reduction in hospitalizations for pneumonia or influenza was already observed by calendar week 3, 2022 (5 vs. 15 events, IRR 0.33 [95% CI, 0.11-0.94]; p 0.037). DISCUSSION: In a post-hoc analysis, QIV-HD was associated with lower incidence rates of hospitalizations for pneumonia or influenza and all-cause hospitalizations compared with QIV-SD, with trends evident independent of influenza circulation levels. Our exploratory results correspond to a number needed to treat of 65 (95% CI 35-840) persons vaccinated with QIV-HD compared with QIV-SD to prevent one additional all-cause hospitalization per season. Further research is needed to confirm these hypothesis-generating findings.

Electronically Delivered Nudges to Increase Influenza Vaccination Uptake in Older Adults With Diabetes: A Secondary Analysis of the NUDGE-FLU Trial.

Importance: Influenza vaccination is associated with a reduced risk of mortality in patients with diabetes, but vaccination rates remain suboptimal. Objective: To assess the effect of electronic nudges on influenza vaccination uptake according to diabetes status. Design, Setting, and Participants: The NUDGE-FLU (Nationwide Utilization of Danish Government Electronic Letter System for Increasing Influenza Vaccine Uptake) trial was a nationwide clinical trial of Danish citizens 65 years or older that randomized participants at the household level to usual care or 9 different electronic nudge letters during the 2022 to 2023 influenza season. End of follow-up was January 1, 2023. This secondary analysis of the NUDGE-FLU trial was performed from May to July 2023. Intervention: Nine different electronic nudge letters designed to boost influenza vaccination were sent in September to October 2022. Effect modification by diabetes status was assessed in a pooled analysis of all intervention arms vs usual care and for individual letters. Main Outcomes and Measures: The primary end point was receipt of a seasonal influenza vaccine. Results: The trial included 964 870 participants (51.5% female; mean [SD] age, 73.8 [6.3] years); 123 974 had diabetes. During follow-up, 83.5% with diabetes vs 80.2% without diabetes received a vaccine (P < .001). In the pooled analysis, nudges improved vaccination uptake in participants without diabetes (80.4% vs 80.0%; difference, 0.37 percentage points; 99.55% CI, 0.08 to 0.66), whereas there was no evidence of effect in those with diabetes (83.4% vs 83.6%; difference, -0.19 percentage points; 99.55% CI, -0.89 to 0.51) (P = .02 for interaction). In the main results of NUDGE-FLU, 2 of the 9 behaviorally designed letters (cardiovascular benefits letter and a repeated letter) significantly increased uptake of influenza vaccination vs usual care; these benefits similarly appeared attenuated in participants with diabetes (cardiovascular gain letter: 83.7% vs 83.6%; difference, 0.04 percentage points; 99.55% CI, -1.52 to 1.60; repeated letter: 83.5% vs 83.6%; difference, -0.15 percentage points; 99.55% CI, -1.71 to 1.41) vs those without diabetes (cardiovascular gain letter: 81.1% vs 80.0%; difference, 1.06 percentage points; 99.55% CI, 0.42 to 1.70; repeated letter: 80.9% vs 80.0%; difference, 0.87 percentage points; 99.55% CI, 0.22 to 1.52) (P = .07 for interaction). Conclusions and Relevance: In this exploratory subgroup analysis, electronic nudges improved influenza vaccination uptake in persons without diabetes, whereas there was no evidence of an effect in persons with diabetes. Trials are needed to investigate the effect of digital nudges specifically tailored to individuals with diabetes. Trial Registration: ClinicalTrials.gov Identifier: NCT05542004.

Calcium Channel Blockers and the Risk of Exacerbation in Patients with Chronic Obstructive Pulmonary Disease: A Nationwide Study of 48,488 Outpatients.

Patients with chronic obstructive pulmonary disease (COPD) are prone to developing arterial hypertension, and many patients are treated with the calcium channel blocker amlodipine. However, it remains unclear whether using this drug potentially affects the risk of acute severe exacerbations (AECOPD) and all-cause mortality in these patients. The data were collected from Danish national registries, containing complete information on health, prescriptions, hospital admissions, and outpatient clinic visits. The COPD patients (n = 48,488) were matched via propensity score on known predictors of the primary outcome in an active comparator design. One group was exposed to amlodipine treatment, and the other was exposed to bendroflumethiazide, since both of these drugs are considered to be the first choice for the treatment of arterial hypertension according to Danish guidelines. The use of amlodipine was associated with a reduced risk of death from all causes at the 1-year follow-up (hazard ratio 0.69, 95% confidence interval: 0.62-0.76) compared with the use of bendroflumethiazide in the matched patients. No difference in the risk of severe AECOPD was found. In the COPD patients, amlodipine use was associated with a lower risk of death from all causes compared with the use of bendroflumethiazide. Amlodipine seems to be a safe first choice for the treatment of arterial hypertension in COPD patients.

Parameters associated with improvement of systolic function in patients with heart failure.

AIMS: Identifying clinical and echocardiographic parameters associated with improvement in systolic function in outpatients with heart failure with reduced ejection fraction (HFrEF) could lead to more targeted treatment improving systolic function and outcome. METHODS: In a retrospective cohort study, echocardiographic examinations from the first and final visit of 686 patients with HFrEF at the heart failure clinic at Gentofte Hospital were retrieved and analysed. Parameters associated with left ventricular ejection fraction (LVEF) improvement and survival according to LVEF improvement were assessed using linear regression and Cox regression, respectively. Beta-coefficients (ß-coef) are standardised. Strain values are absolute. RESULTS: While undergoing heart failure treatment, 559 (81.5%) patients improved systolic function ( Δ LVEF >0%), with 100 (14.6%) being super responders defined by LVEF improvement >20%. After multivariable adjustment, LVEF improvement was significantly associated with a less impaired global longitudinal strain (ß-coef 0.25, p<0.001), higher tricuspid annular plane systolic excursion (ß-coef 0.09, p=0.018), smaller left ventricular internal dimension in diastole (ß-coef -0.15, p=0.011), lower E-wave/A-wave ratio (ß-coef -0.13, p=0.003), higher heart rate (ß-coef 0.18, p<0.001) and absence of ischaemic cardiomyopathy (ß-coef -0.11, p=0.010) and diabetes (ß-coef -0.081, p=0.033) at baseline. Mortality incidence rates differed with LVEF improvement ( Δ LVEF <0% vs Δ LVEF >0%, 8.3 vs 4.3 per 100 person years, p=0.012). Greater improvement in LVEF was associated with significantly lower mortality risk (tertile 1 vs tertile 3, HR 3.23, 95% CI 1.39 to 7.51, p=0.006). CONCLUSION: In this outpatient HFrEF cohort, most patients improved systolic function. Heart failure aetiology, comorbidities and echocardiographic measures of heart structure and function were significantly, independently associated with future LVEF improvement. Greater LVEF improvement was significantly associated with lower mortality.

Fibrin degradation products and survival in patients with chronic obstructive pulmonary disease: a protocolized prospective observational study.

BACKGROUND: Patients with chronic obstructive pulmonary disease (COPD) have a high incidence of cardiovascular disease including thromboembolisms. Fibrin degradation products, like D-dimer, have been associated with death from all causes in healthy individuals and COPD patients. We aimed to determine the (i) association between D-dimer levels and all-cause mortality and time being alive and out of a hospital, (ii) possible modifying effect of anticoagulant treatment,, and (iii) distribution of D-dimer in patients with moderate to severe COPD. METHODS: Results of routinely measured stable phase D-dimer samples from COPD-outpatients at Copenhagen University Hospital - Herlev and Gentofte, COPD-outpatient clinic were collected using the Danish registries. These were used to examine whether COPD-patients with a D-dimer level in the upper quartile, had a higher risk of death from all causes within 365 days. RESULTS: In the unadjusted Cox proportional hazards regression we found an association between high D-dimer and all-cause mortality: Hazard ratio (HR): 2.3 (95% Confidence Interval (CI) 1.1-4.7). In the fully adjusted regression, the HR was 1.8 (CI 0.8-3.9). We did not find any interaction between D-dimer and anticoagulant or antiplatelet therapy. For the secondary outcome, proportion of days alive and out of hospital in 365 days (pDAOH), the unadjusted multiple linear regression had an association between high D-dimer level and pDAOH: -2.7% points (pp) (CI -3.9 pp - -1.5 pp), which was attenuated to -1,7pp (-2.9pp - -0.4pp) in the fully adjusted regression. CONCLUSIONS: In patients with moderate to severe COPD, patients with a high level of D-dimer were more likely to die; however, the signal was not strong in the adjusted analyses and our results do not support unselected risk stratification with D-dimer in COPD-outpatients.

Influenza vaccination and cardiovascular events in patients with ischaemic heart disease and heart failure: A meta-analysis.

AIM: Randomized controlled trials (RCTs) enrolling patients at high cardiovascular risk have found that influenza vaccination may reduce the incidence of cardiovascular events. We performed an updated meta-analysis assessing the effect of influenza vaccination on the incidence of cardiovascular events in patients with ischaemic heart disease or heart failure. METHODS AND RESULTS: We searched PubMed, EMBASE and other sources to identify RCTs examining the effect of influenza vaccination on the incidence of cardiovascular events assessed as efficacy outcomes in patients with ischaemic heart disease or heart failure. Eligible studies followed patients for at least one influenza season, defined as a minimum duration of 6 months. The primary endpoint was a composite of cardiovascular death, acute coronary syndrome, stent thrombosis or coronary revascularization, stroke or heart failure hospitalization. The secondary endpoints were cardiovascular death and all-cause death. Two investigators independently identified and extracted data from studies. Results were compared using hazard ratios (HRs) in both random effects and fixed effects models. We included five peer-reviewed and one non peer-reviewed RCTs for a total of 9340 patients. Five trials included patients with ischaemic heart disease (n = 4211) and one trial included patients with heart failure (n = 5129). Influenza vaccination was associated with a reduced incidence of the primary composite endpoint (random effects HR [rHR] 0.74, 95% confidence interval [CI] 0.63-0.88, p < 0.001, I2 = 52%), cardiovascular death (rHR 0.63, 95% CI 0.42-0.95, p = 0.028, I2 = 58%) and all-cause death (rHR 0.72, 95% CI 0.54-0.95, p = 0.0227, I2 = 52%). Results were similar when non peer-reviewed data were excluded. CONCLUSION: In this meta-analysis of available RCTs in patients at high cardiovascular risk, influenza vaccination was associated with a reduced incidence of cardiovascular events, cardiovascular death and all-cause death as compared to placebo or no treatment.

Left atrial functional measurements' utility in predicting long-term risk of atrial fibrillation after isolated CABG.

BACKGROUND: Atrial fibrillation (AF) is the most common cardiac arrhythmia following coronary artery bypass grafting (CABG). We hypothesized that measures of left atrial (LA) function would be useful in predicting AF in patients undergoing CABG. METHODS AND RESULTS: In the study, 611 patients were included after CABG. All patients had echocardiograms performed preoperatively and LA functional measurements were assessed. These measurements were LA maximum volume index (LAVmax), LA minimum volume index (LAVmin) and LA emptying fraction (LAEF). The endpoint was AF occurring >14 days after surgery. During the follow-up period of a median of 3.7 years, 52 (9%) developed AF. The mean age was 67 years, 84% were male and the average left ventricle ejection fraction was 50%. Patients who developed AF had a lower CCS class and lower LAEF (40 vs. 45%), otherwise no clinical differences were observed between outcome groups. No functional LA measurements were significant predictors of AF in the whole CABG population. However, in patients with normal-sized LA (n = 532, events: 49), both LAEF and LAVmin were univariable predictors of AF. When the functional measurements were adjusted for the CHADS2 score, both LAVmin (HR = 1.07 [1.01-1.13], p = .014) and LAEF (HR: 1.02 [1.00-1.03], p = .023), remained significant predictors. CONCLUSION: No echocardiographic measurements were significant predictors of AF after CABG. In patients with a normal LA size, LAVmin as well as LAEF were significant predictors of AF.

Electronic nudges to increase influenza vaccination uptake among patients with heart failure: A pre-specified analysis of the NUDGE-FLU trial.

AIMS: Seasonal influenza vaccination is strongly recommended in patients with heart failure (HF). The NUDGE-FLU trial recently found two electronic behavioural nudging letter strategies - a letter highlighting potential cardiovascular benefits of vaccination and a repeated letter at day 14 -effective in increasing influenza vaccination in Denmark. The aims of this pre-specified analysis was to further examine vaccination patterns and effects of these behavioural nudges in patients with HF including potential off-target effects on guideline-directed medical therapy (GDMT) use. METHODS AND RESULTS: The nationwide NUDGE-FLU trial randomized 964 870 Danish citizens ≥65 years to usual care or nine different electronic nudging letter strategies. Letters were delivered through the official Danish electronic letter system. The primary endpoint was the receipt of an influenza vaccine; additional outcomes for this analysis included GDMT use. In this analysis, we also assessed influenza vaccination rates in the overall Danish HF population including those <65 years (n = 65 075). During the 2022-2023 season, influenza vaccination uptake was 71.6% in the overall Danish HF population but this varied considerably with only 44.6% uptake in those <65 years. A total of 33 109 NUDGE-FLU participants had HF at baseline. Vaccination uptake was higher among those on higher levels of baseline GDMT (≥3 classes: 85.3% vs. ≤2 classes: 81.9%; p < 0.001). HF status did not modify the effects of the two overall successful nudging strategies on influenza vaccination uptake (cardiovascular gain-framed letter: pinteraction = 0.37; repeated letter: pinteraction = 0.55). No effect modification was observed across GDMT use levels for the repeated letter (pinteraction = 0.88), whereas a trend towards attenuated effect among those on low levels of GDMT was observed for the cardiovascular gain-framed letter (pinteraction = 0.07). The letters had no impact on longitudinal GDMT use. CONCLUSIONS: Approximately one in four patients with HF did not receive influenza vaccination with a pronounced implementation gap in those <65 years where less than half were vaccinated. HF status did not modify the effectiveness of cardiovascular gain-framed and repeated electronic nudging letters in increasing influenza vaccination rates. No unintended negative effects on longitudinal GDMT use were observed. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov NCT05542004.

Electronic nudges to increase influenza vaccination uptake in Denmark: a nationwide, pragmatic, registry-based, randomised implementation trial.

BACKGROUND: Influenza vaccination rates remain suboptimal despite effectiveness in preventing influenza infection and related complications. We investigated whether behavioural nudges, delivered via a governmental electronic letter system, would increase influenza vaccination uptake among older adults in Denmark. METHODS: We did a nationwide, pragmatic, registry-based, cluster-randomised implementation trial during the 2022-23 influenza season in Denmark. All Danish citizens aged 65 years or older or turning 65 years by Jan 15, 2023 were included. We excluded individuals living in nursing homes and individuals who had an exemption from the Danish mandatory governmental electronic letter system. Households were randomly assigned (9:1:1:1:1:1:1:1:1:1) to usual care or nine different electronic letters designed on the basis of different behavioural nudging concepts. Data were sourced from nationwide Danish administrative health registries. The primary endpoint was receipt of influenza vaccination on or before Jan 1, 2023. The primary analysis assessed an analytical set of one randomly selected individual per household, and a sensitivity analysis included all randomly assigned individuals and accounted for within-household correlation. The trial is registered with ClinicalTrials.gov, NCT05542004. FINDINGS: We identified 1 232 938 individuals aged 65 years or older in Denmark and excluded 56 436 (4·6%) individuals living in nursing homes and 211 632 (17·2%) with an exemption from the electronic letter system. We randomly assigned 964 870 (78·3%) participants across 691 820 households. Compared with usual care, influenza vaccination rates were higher in the group receiving an electronic letter highlighting potential cardiovascular benefits of vaccination (81·00% vs 80·12%; difference 0·89 percentage points [99·55% CI 0·29-1·48]; p<0·0001) and the group receiving repeated letters at randomisation and at day 14 (80·85% vs 80·12%; difference 0·73 percentage points [0·13-1·34]; p=0·0006). These strategies improved vaccination rates across major subgroups including those with and without established cardiovascular disease. The cardiovascular gain-framed letter was particularly effective among participants who had not been vaccinated for influenza in the previous season (pinteraction=0·0002). A sensitivity analysis of all randomly assigned individuals accounting for within-household clustering yielded similar findings. INTERPRETATION: Electronically delivered letters highlighting potential cardiovascular benefits of influenza vaccination or sent again as a reminder significantly increased vaccination uptake across Denmark. Although the magnitude of effectiveness was modest, the low-touch, inexpensive, and highly scalable nature of these electronic letters might be informative for future public health campaigns. FUNDING: Sanofi.

Influenza and cardiovascular disease pathophysiology: strings attached.

A link between influenza infection and cardiovascular morbidity has been known for almost a century. This narrative review examined the cardiovascular complications associated with influenza and the potential mechanisms behind this relationship. The most common reported cardiovascular complications are cardiovascular death, myocardial infarction, and heart failure hospitalization. There are multiple proposed mechanisms driving the increased risk of cardiovascular complications. These mechanics involve influenza-specific effects such as direct cardiac infection and endothelial dysfunction leading to plaque destabilization and rupture, but also hypoxaemia and systemic inflammatory responses including increased metabolic demand, biomechanical stress, and hypercoagulability. The significance of the individual effects is unclear, and thus whether influenza directly or indirectly causes cardiovascular events is unknown. In conclusion, the risk of acute cardiovascular morbidity and mortality is elevated during influenza infection. The proposed underlying pathophysiological mechanisms support this association, but systemic responses to infection may drive this relationship.

Effect of Electronic Nudges on Influenza Vaccination Rate in Older Adults With Cardiovascular Disease: Prespecified Analysis of the NUDGE-FLU Trial.

BACKGROUND: Influenza vaccines have been demonstrated to effectively reduce the incidence of influenza infection and potentially associated risks of cardiovascular events in patients with cardiovascular disease (CVD). Despite strong guideline and public health endorsements, global influenza vaccination rates in patients with CVD are highly variable. This prespecified analysis of NUDGE-FLU (Nationwide Utilization of Danish Government Electronic Letter System for Increasing Influenza Vaccine Uptake) examined the effect of digital behavioral nudges on influenza vaccine uptake based on the presence of CVD. METHODS: NUDGE-FLU was a randomized, pragmatic, nationwide, register-based trial that included Danish citizens 65 years of age or older during the 2022 to 2023 influenza season. Households were randomized in a 9:1:1:1:1:1:1:1:1:1 ratio to usual care or 9 electronic letters with designs based on behavioral concepts. Danish nationwide registers were used to collect baseline and outcome data. The primary end point was receipt of an influenza vaccine on or before January 1, 2023. The effects of the intervention letters were examined according to the presence of CVD and across cardiovascular subgroups that included heart failure, ischemic heart disease, and atrial fibrillation. RESULTS: Of 964 870 NUDGE-FLU participants from 691 820 households, 264 392 (27.4%) had CVD. During follow-up, 83.1% of participants with CVD versus 79.2% of participants without CVD received an influenza vaccination (P<0.001). Compared with usual care, a letter emphasizing the potential cardiovascular benefits of influenza vaccination increased vaccination rates; this effect was consistent in participants with CVD (absolute difference, +0.60 percentage points [99.55% CI, -0.48 to 1.68]) and without CVD (+0.98 percentage points [99.55% CI, 0.27-1.70; P for interaction=0.41). A repeated letter strategy with a reminder follow-up letter 14 days later was also effective in increasing influenza vaccination, irrespective of CVD (CVD: absolute difference, +0.80 percentage points [99.55% CI, -0.27 to 1.86]; no CVD: +0.67 percentage points [99.55% CI, -0.06 to 1.40]; P for interaction=0.77). Effectiveness of both nudging strategies was consistent across all major CVD subgroups. None of the other 7 nudging strategies were effective, regardless of CVD status. CONCLUSIONS: Electronic letter interventions emphasizing the potential cardiovascular benefits of influenza vaccination and using a reminder letter strategy were similarly beneficial in increasing influenza vaccination rates among older adults with and without CVD and across cardiovascular subgroups. Electronic nudges may improve influenza vaccine uptake in individuals with CVD. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT05542004.

A Composite Score Summarizing Use and Dosing of Evidence-Based Medical Therapies in Heart Failure: A Nationwide Cohort Study.

BACKGROUND: As heart failure therapeutic care becomes increasingly complex, a composite medical therapy score could be useful to conveniently summarize background medical therapy. We applied the composite medical therapy score developed by the Heart Failure Collaboratory (HFC) to the Danish heart failure with reduced ejection fraction population to evaluate its external validation including assessing the distribution of the score and its association with survival. METHODS: In a retrospective nationwide cohort study, we identified all Danish heart failure with reduced ejection fraction patients alive on July 1, 2018, and assessed their treatment doses. Patients were excluded if they did not have at least 365 days for up-titration of medical therapy prior to identification. The HFC score (range 0-8) accounts for use and dosing of multiple therapies prescribed to each patient. Risk-adjusted association between the composite score and all-cause mortality was examined. RESULTS: In total, 26 779 patients (mean age 71.9 years; 32% women) were identified. At baseline, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker was used in 77%, ß-blocker in 81%, mineralocorticoid receptor antagonist in 30%, angiotensin receptor-neprilysin inhibitor in 2%, and ivabradine in 2%. The median HFC score was 4. After multivariable adjustment, higher HFC scores were independently associated with lower mortality (≥median versus

Nationwide Utilization of Danish Government Electronic letter system for increasing inFLUenza vaccine uptake (NUDGE-FLU): Study protocol for a nationwide randomized implementation trial.

BACKGROUND: Annual influenza vaccination is widely recommended in older adults and other high-risk groups including patients with cardiovascular disease. The real-world effectiveness of influenza vaccination is limited by suboptimal uptake and effective strategies for increasing vaccination rates are therefore needed. The purpose of this trial is to investigate whether behavioral nudges digitally delivered via the Danish nationwide mandatory governmental electronic letter system can increase influenza vaccination uptake among older adults. METHODS: The NUDGE-FLU trial is a randomized implementation trial randomizing all Danish citizens aged 65 years and above without an exemption from the Danish mandatory governmental electronic letter system to receive no digitally delivered behavioral nudge (usual care arm) or to receive one of 9 electronic letters (intervention arms) each leveraging different behavioral science strategies. The trial has randomized 964,870 participants with randomization clustered at the household level (n = 691,820 households). Intervention letters were delivered on September 16, 2022, and follow-up is currently ongoing. All trial data are captured using the nationwide Danish administrative health registries. The primary end point is the receipt of an influenza vaccine on or before January 1, 2023. The secondary end point is time to vaccination. Exploratory end points include clinical events such as hospitalization for influenza or pneumonia, cardiovascular events, all-cause hospitalization, and all-cause mortality. DISCUSSION: The nationwide randomized NUDGE-FLU trial is one of the largest implementation trials ever conducted and will provide important insights into effective communication strategies to maximize vaccination uptake among high-risk groups. TRIAL REGISTRATION: Clinicaltrials.gov: NCT05542004, registered September 15, 2022, https://clinicaltrials.gov/ct2/show/NCT05542004.

Global, regional and national estimates of influenza-attributable ischemic heart disease mortality.

Background: Influenza virus infection is associated with incident ischemic heart disease (IHD) events. Here, we estimate the global, regional, and national IHD mortality burden attributable to influenza. Methods: We used vital registration data from deaths in adults ≥50 years (13.2 million IHD deaths as underlying cause) to assess the relationship between influenza activity and IHD mortality in a non-linear meta-regression framework from 2010 to 2019. This derived relationship was then used to estimate the global influenza attributable IHD mortality. We estimated the population attributable fraction (PAF) of influenza for IHD deaths based on the relative risk associated with a given level of weekly influenza test positivity rate and multiplied PAFs by IHD mortality from the Global Burden of Disease study. Findings: Influenza activity was associated with increased risk of IHD mortality across all countries analyzed. The mean PAF of influenza for IHD mortality was 3.9% (95% uncertainty interval [UI] 2.5-5.3%), ranging from <1% to 10%, depending on country and year. Globally, 299,858 IHD deaths (95% UI 191,216-406,809) in adults ≥50 years could be attributed to influenza, with the highest rates per 100,000 population in the Central Europe, Eastern Europe and Central Asia Region (32.3; 95% UI 20.6-43.8), and in the North Africa and Middle East Region (26.7; 95% UI 17-36.2). Interpretation: Influenza may contribute substantially to the burden of IHD. Our results suggest that if there were no influenza, an average of 4% of IHD deaths globally would not occur. Funding: Collaborative study funded by Sanofi Vaccines.