Influenza-Like Illness Activity and Heart Failure Hospitalizations

Study Questions:

What is the temporal association between influenza activity and hospitalizations due to heart failure (HF) and myocardial infarction (MI)?

Methods:

The investigators used data from the community surveillance component of the ARIC (Atherosclerosis Risk in Communities) study, a population-based study with hospitalizations sampled from four US communities, and data collected from 451,588 adults aged 35-84 years residing in the ARIC communities from annual cross-sectional stratified random samples of hospitalizations during October 2010 to September 2014. Monthly influenza activity, defined as the percentage of patient visits to sentinel clinicians for influenza-like illness by state, as reported by the Centers for Disease Control and Prevention Surveillance Network were obtained. The primary outcome was the monthly frequency of MI hospitalizations (n = 3,541) and HF hospitalizations (n = 4,321), collected through community surveillance and adjudicated as part of the ARIC study. The investigators used a Poisson regression model to associate monthly influenza activity with hospitalizations for MI and HF.

Results:

Between October 2010 and September 2014, 2,042 (47.3%) and 1,599 (45.1%) of the sampled patients who were hospitalized for HF and MI, respectively, were women and 2,391 (53.3%) and 2,013 (57.4%) were white, respectively. A 5% monthly absolute increase in influenza activity was associated with a 24% increase in HF hospitalization rates, standardized to the total population in each community, within the same month after adjusting for region, season, race/ethnicity, sex, age, and number of MI/HF hospitalizations from the month before (incidence rate ratio, 1.24; 95% confidence interval [CI], 1.11-1.38; p < 0.001), while overall influenza activity was not significantly associated with MI hospitalizations (incidence rate ratio, 1.02; 95% CI, 0.90-1.17; p = 0.72). Influenza activity in the months before hospitalization was not associated with either outcome. Our model suggests that in a month with high influenza activity, approximately 19% of HF hospitalizations (95% CI, 10-28%) could be attributable to influenza.

Conclusions:

The authors concluded that influenza activity was temporally associated with an increase in HF hospitalizations across four influenza seasons.

Perspective:

This study reports that influenza-like illness activity was associated with an increase in HF hospitalizations within the same month and appears temporally associated with the risk of cardiovascular hospitalization. While these data suggest that influenza activity should be addressed in efforts to prevent HF hospitalizations, additional prospective studies are indicated to assess whether such strategies to reduce influenza activity at the population level will actually reduce the incidence of MI and HF hospitalizations.

Clinical Topics: Acute Coronary Syndromes, Heart Failure and Cardiomyopathies, Prevention, Acute Heart Failure

Keywords: Acute Coronary Syndrome, Heart Failure, Hospitalization, Influenza, Human, Myocardial Infarction, Risk, Secondary Prevention


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