Flu Vaccine Linked to Lower CV Risk in Diabetes Patients

In patients with type 2 diabetes, influenza vaccination was associated with reductions in rates of hospital admission for specific cardiovascular events, according to a new study.

“Studies assessing influenza vaccine effectiveness in people with diabetes are scarce and have shown inconclusive results,” the researchers said. “None of the previous studies adjusted for residual confounding, and most of them reported composite end-points such as admission to hospital for any cause. Furthermore, we are not aware of any studies assessing the potential benefits of influenza vaccination against individual cardiovascular events in people with type 2 diabetes.”
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The investigators conducted a retrospective cohort study using primary and secondary care data from the Clinical Practice Research Datalink in England, over a 7-year period between 2003-2004 and 2009-2010. They enrolled 124,503 adults with type 2 diabetes, and outcome measures included admission to the hospital for acute myocardial infarction (MI), stroke, heart failure or pneumonia/influenza, and death. The investigators fitted Poisson regression models for influenza and off-season periods to estimate incidence rate ratios (IRR) for cohorts who had and had not received the vaccine. They used estimates for the summer, when influenza activity is low, to adjust for residual confounding.

Participants contributed to 623,591 person-years of observation. The researchers found vaccine recipients to be older and had more comorbid conditions compared with nonrecipients. After they adjusted for covariates and residual confounding, vaccination was associated with significantly lower admission rates for stroke (IRR, 0.70; 95% confidence interval [CI], 0.53-0.91), heart failure (IRR, 0.78; 95% CI, 0.65-0.92), and pneumonia or influenza (IRR, 0.85; 95% CI, 0.74-0.99), as well as all-cause death (IRR, 0.76; 95% CI, 0.65-0.83), and a nonsignificant change for acute MI (IRR, 0.81; 95% CI, 0.62-1.04) during the influenza seasons.

“Concerns about the benefits of influenza vaccination in older adults and patients with chronic illnesses affect the acceptance and uptake of influenza vaccination in many countries, including those with comprehensive immunization programs,” the researchers concluded. “This study has shown that people with type 2 diabetes may derive substantial benefits from current vaccines, including protection against hospital admission for some major cardiovascular outcomes. These findings underline the importance of influenza vaccination as part of comprehensive secondary prevention in this high-risk population.”

—Mike Bederka

Reference:
Vamos EP, Pape UJ, Curcin V, et al. Effectiveness of the influenza vaccine in preventing admission to hospital and death in people with type 2 diabetes [published online July 25, 2016]. CMAJ. doi:10.1503/cmaj.151059.