Mortality and Morbidity Benefit After Influenza Vaccination in High Cardiovascular Risk Population: A Systematic...

Area of Science:

• Cardiology
• Infectious Diseases
• Public Health

Background:

• Influenza infection poses a significant cardiovascular risk for individuals with ischemic heart disease (IHD) or heart failure (HF).
• Annual influenza vaccination is recommended for these high-risk populations, but its precise cardiovascular benefits require ongoing evaluation.

Purpose of the Study:

• To conduct an updated meta-analysis assessing the cardiovascular benefits of influenza vaccination in patients with IHD or HF.
• To evaluate the impact of influenza vaccination on mortality and major cardiovascular events in these vulnerable patient groups.

Main Methods:

• A meta-analysis combining individual patient data (IPD) and study-level data from 23 studies (7 RCTs, 16 observational) involving over 1.1 million patients.
• Utilized Cox models to estimate pooled hazard ratios (HRs) for various outcomes, including all-cause mortality, cardiovascular mortality, myocardial infarction (MI), stroke, and major adverse cardiovascular events (MACE).
• Explored heterogeneity through subgroup, sensitivity, and meta-regression analyses, with study quality assessed using RoB 2 and ROBINS-I tools.

Main Results:

• Influenza vaccination significantly reduced all-cause mortality (HR=0.72) and cardiovascular mortality (HR=0.77).
• A lower risk of myocardial infarction (MI) was observed in vaccinated patients (HR=0.81), though effects on stroke and MACE were not statistically significant.
• IPD meta-analysis (n=22,443) showed a 38% reduction in mortality (HR=0.62), with the most substantial benefits observed within the first four months post-vaccination.

Conclusions:

• Influenza vaccination markedly lowers mortality and provides significant cardiovascular protection for patients with IHD or HF.
• Annual vaccination is supported as an effective secondary prevention strategy in these high-risk cardiovascular populations.
• The protective effects were consistent across diverse patient subgroups and study designs.