Abstract 15657: Influenza Vaccination and All-cause Mortality Among Adults With Heart Failure in an Integrated Healthcare Delivery System, 2009-2018

Abstract

Background: Vaccinations prevent respiratory infections in heart failure (HF) patients, leading to less HF decompensation. Given a growing interest around influenza vaccination and mortality reduction, we examined the association between influenza vaccination and all-cause mortality among members with HF in Kaiser Permanente Southern California. Methods: We identified members with HF by ICD-9/10 diagnosis codes prior to September 1 each year from 2009-2017. The first flu vaccination in each season (September 1-May 31) was recorded. Vaccinated/unvaccinated members were matched 1:1 on age, sex, and ejection fraction. Matched pairs were followed from the vaccinated member’s vaccination date through the end of the season for mortality, with the last date of follow-up on May 31, 2018. Frequency of healthcare utilization in the year before each season was compared between vaccinated and unvaccinated members. We calculated unadjusted and utilization-adjusted rate ratios (RR) and 95% confidence intervals (CI) for the association between vaccination and mortality. Results: Between 2009-2018, influenza vaccination among HF members increased from 74.8% to 80.3% and the number of vaccinated and unvaccinated matched pairs increased to 4,451 through the 2017-2018 season. The proportions of vaccinated and unvaccinated members with ≥ 1 prior inpatient visit and ≥1 prior emergency department (ED) visit were similar (46.2% vs 44.6% and 34.3% vs 32.6%, respectively). More unvaccinated than vaccinated members had ≥ 5 outpatient visits (41.9% vs 28.1%). After adjustment for inpatient, outpatient and ED visits, vaccinated members had between a 16% and 36% lower mortality rate across all seasons (RR 0.64 [95% CI 0.55, 0.75] in 2013-2014 and RR 0.84 [95% CI 0.73, 0.96] in 2017-2018). (Table) Conclusion: Influenza vaccination was likely associated with a lower mortality rate among HF patients. Future work will examine the potential confounding by comorbidities and treatments.