Recent data indicate that influenza viruses are associated with acute ischemic heart disease events in those aged at least 50 years.
“The data from this study support previous reports of the temporal association of myocardial infarction events with influenza outbreaks over multiple influenza seasons in a large population of older individuals,” James King, MD, of the U.S. Office of Health and Human Services, told Infectious Disease News. “What was unique about this study was that in addition we demonstrated that the intensity of the influenza outbreaks, as measured by medically attended acute respiratory illness-related emergency department visits, was positively correlated to increases in ischemic heart disease hospitalizations observed during influenza outbreaks.”
King and colleagues from the University of Maryland School of Medicine evaluated relationships between influenza outbreak timeframes and rates of ischemic heart disease events and deaths among Maryland adults aged 50 years and older. Data on influenza were obtained from the 2001-2002 influenza season through the 2007-2009 season. Data on ischemic heart disease events and deaths were pooled from 57 hospitals in Maryland from July 1, 2001, to June 30, 2008. An intense influenza outbreak period is the 4-week period, including the peak week, with the most positive influenza tests.
During the intense influenza outbreak periods in all of the study years, adults aged 50 years and older had higher rate ratios of ischemic heart disease hospitalizations (RR=1.06), death (RR=1.16) and combination ischemic heart disease and medically attended acute respiratory illness (RR=1.42). The researchers also found that 360 ischemic heart disease hospitalizations and 97 deaths throughout the study period could be attributed to the intense influenza outbreak period. The rate ratios for hospitalizations increased with age.
“Annual vaccination rates of older individuals against influenza are not as high as we would hope,” King said. “Further evidence linking influenza outbreaks with acute myocardial infarction may increase the use of influenza vaccine in this group. Unfortunately, we know that the immunogenicity of currently licensed influenza vaccine decreases with increasing age. The results of this and similar studies may increase the research, development and use of more immunologically potent but safe influenza vaccine candidates in the near future.”
Disclosure: The researchers report no relevant financial disclosures.