心不全患者にとってインフルエンザワクチンは有益である(Abstract 18-A-13676-ACC)

季節毎のインフルエンザワクチンは心不全患者の死亡リスクを半減する
Seasonal Flu vaccine cuts risk of death in half for people with heart failure
心不全患者において、季節毎のインフルエンザ(flu)ワクチン接種を受けることにより、接種を受けた年のインフルエンザ流行期の全死亡リスクが50% 低下し、その後の年の死亡リスクが20% 低下した、とAmerican College of Cardiology's 67th Annual Scientific Sessionで発表された。心不全患者78,000人超を対象としたこのメタ解析は、fluワクチン接種により心血管系の原因により入院するリスクを22% 低下させることも示した。
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For people with heart failure, getting a seasonal influenza (flu) vaccine in a given year was associated with a 50 percent drop in the risk of death during flu season and a 20 percent drop in the risk of death during the rest of the year, according to research presented at the American College of Cardiology's 67th Annual Scientific Session.

The study comes amid a flu season that has brought higher than normal rates of infection and death. Influenza and flu-related complications can cause death even in otherwise healthy people. This is the first study to examine the relationship between influenza vaccination and death or hospitalization in heart failure patients through meta-analysis.

"It is well known that influenza infection is associated with increased risk for mortality in heart failure patients," said Hidekatsu Fukuta, MD, a cardiologist at Nagoya City University Graduate School of Medical Sciences in Nagoya, Japan, and the study's lead author. "Given the high mortality rate and the relatively low influenza vaccination rates in heart failure patients worldwide, our study supports a wider use of influenza vaccination in heart failure patients."

Researchers analyzed six studies conducted in the U.S., Europe and Asia that together included data for more than 78,000 patients with heart failure. Five of the studies were observational and one was a retrospective analysis of results from a clinical trial. The researchers found no randomized control trials designed specifically to investigate influenza vaccination in patients with heart failure.

Taken together, the studies showed that getting the flu vaccine reduced the risk of dying (from any cause) by about half during flu season and by about one-fifth during the rest of the year. Vaccination was also associated with a 22 percent reduction in the risk of being hospitalized for cardiovascular problems. 

In the studies, the proportion of heart failure patients receiving the flu vaccine ranged from 26 to 86 percent, reflecting wide variability in vaccination rates among these patients. Researchers suggested this variability may be due to limited guideline recommendations for influenza vaccination in heart failure patients. While the Heart Failure Society of America recommends annual influenza vaccination in all heart failure patients who do not have known contraindications, the ACC/AHA and European Society of Cardiology guidelines do not make such specific recommendations for heart failure patients. The Centers for Disease Control and Prevention recommends that everyone age 6 months and older get a flu shot each year and encourages people with heart disease to stay current on immunizations and talk with their doctor. 

The findings suggest influenza vaccination is beneficial for patients with heart failure, although researchers cautioned that while observational studies can show associations, they do not necessarily prove cause and effect.

"Randomized controlled studies should be planned to confirm our observed potential survival benefit of influenza vaccination in these patients," Fukuta said.