Influenza vaccination and mortality among adults with heart failure in an integrated healthcare delivery system, 2009-2018.

BACKGROUND: Influenza infection can result in decompensation or exacerbation of heart failure (HF) symptoms, hospitalization, and death. OBJECTIVE: To examine the association of influenza vaccination with mortality and hospitalization during influenza and non-influenza seasons between 2009 and 2018. DESIGN, SETTING, AND PARTICIPANTS: In this prospective, observational cohort study, we included Kaiser Permanente Southern California members with a HF diagnosis prior to September 1 each year from 2009 to 2017. EXPOSURE: The first influenza vaccination in each season (September 1 to May 31) was recorded. Vaccinated/unvaccinated patients were matched 1:1 on age, sex, and ejection fraction at the vaccination date (n-total = 74,870). MAIN OUTCOMES: Patients were followed through the end of each influenza season for all-cause mortality. Secondary outcomes included cardiovascular mortality and all-cause hospitalization. In a sensitivity analysis, we examined mortality in the non-influenza season. RESULTS: Influenza vaccinated vs unvaccinated patients had more comorbidities and higher healthcare utilization. After multivariable adjustment for utilization, sociodemographics, comorbidities, and medications, influenza vaccinated vs unvaccinated patients had a lower risk of all-cause mortality and cardiovascular mortality during the influenza season (hazard ratio [HR] 0.66, 95% confidence interval [CI] 0.63, 0.70 and HR 0.68, 95% CI 0.63, 0.74, respectively) but a higher risk of all-cause hospitalization (HR 1.27, 95% CI 1.21, 1.31). There was no association between influenza vaccination and all-cause or cardiovascular mortality during the non-influenza season (HR 0.99, 95% CI 0.89, 1.09 and HR 1.00, 95% CI 0.84, 1.21, respectively). CONCLUSIONS: Influenza vaccination in HF patients was associated with a lower risk of mortality during the influenza season. Our findings provide support for recommendations of universal influenza vaccination in patients with HF.

Temporal trends in heart failure mortality in an integrated healthcare delivery system, California, and the US, 2001-2017.

BACKGROUND: In recent years, decreases in mortality rates attributable to cardiovascular diseases have slowed but mortality attributable to heart failure (HF) has increased. METHODS: Between 2001-2017, trends in age-adjusted mortality with HF as an underlying cause for Kaiser Permanente Southern California (KPSC) members were derived through linkage with state death files and compared with trends among California residents and the US. Average annual percent change (AAPC) and 95% confidence intervals (CI) were calculated using Joinpoint regression. Analyses were repeated examining HF as a contributing cause of death. RESULTS: In KPSC, the age-adjusted HF mortality rates were comparable to California but lower than the US, increasing from 23.9 per 100,000 person-years (PY) in 2001 to 44.7 per 100,000 PY in 2017, representing an AAPC of 1.3% (95% CI 0.0%, 2.6%). HF mortality also increased in California from 33.9 to 46.5 per 100,000 PY (AAPC 1.5%, 95% CI 0.3%, 2.7%), while remaining unchanged in the US at 57.9 per 100,000 PY in 2001 and 2017 (AAPC 0.0%, 95% CI - 0.5%, 0.5%). Trends among KPSC members ≥ 65 years old were similar to the overall population, while trends among members 45-64 years old were flat between 2001-2017. Small changes in mortality with HF as a contributing cause were observed in KPSC members between 2001 and 2017, which differed from California and the US. CONCLUSION: Lower rates of HF mortality were observed in KPSC compared to the US. Given the aging of the US population and increasing prevalence of HF, it will be important to examine individual and care-related factors driving susceptibility to HF mortality.