The effect of influenza vaccination in patients with heart failure: a systematic review and meta-analysis
A K E Freitas, M V Montenegro, M S B G Silva, L R O S Nascimento, T C Fayyat, F M GuimaraesAbstract
Background
Influenza has been established as one of the principal causes of morbidity and mortality in patients with heart failure (HF), regardless of ejection fraction. It can lead to both short-term and long-term sequelae in affected individuals. Influenza vaccination is widely recommended to prevent serious adverse events in vulnerable populations, including this patient group. However, evidence demonstrating a clear benefit of influenza vaccination on clinical outcomes in patients with HF remains limited.
Purpose
To assess the effect of influenza vaccination on mortality and morbidity in patients with HF.
Methods
Systematic review and meta-analysis performed according to PRISMA guidelines. PubMed, Cochrane, and Web of Science were systematically searched for randomised clinical trials and observational studies comparing cardiovascular outcomes and mortality between vaccinated and unvaccinated patients with HF. The primary outcomes were: all-cause mortality, cardiovascular mortality, and hospitalisation for heart failure. Statistical analysis was performed using RevMan 5.4 software, with p-values less than 0.05 considered significant.
Results
Ten studies were included, enrolling heart-failure populations ranging from 223 to 74,870 participants with broadly comparable vaccinated and non-vaccinated cohorts. Across studies, vaccinated samples ranged from 97 to 37,435 individuals, while non-vaccinated samples ranged from 126 to 37,435. Patients were predominantly older adults (mean age 57-85 years) and commonly presented with multiple comorbidities, including hypertension (35-84%) and diabetes (21-55%). Follow-up duration varied from seasonal observation to up to 4-5 years. Nine studies reported all-cause mortality, and influenza vaccination was associated with a significantly lower risk of death (HR 0.72; 95% CI 0.60-0.86: P=0.0003). Cardiovascular mortality was reported in three studies, showing a similar benefit (HR 0.74: 95% CI 0.57-0,98; P=0.03). Four studies reported hospitalisation for heart failure, where vaccination was also associated with fewer admissions (HR 0.57; 95% CI 0.34–0.96; P=0.03). Across all outcomes, effect estimates consistently favoured vaccination.
Conclusion
In patients with heart failure, influenza vaccination was associated with a reduction in all-cause mortality, cardiovascular mortality, and hospitalisations for HF.For image description, please refer to the figure legend and surrounding text.