October 30, 2013
Flu Vaccine Highly Beneficial for Heart Disease Patients

Toronto—Here’s another reason for pharmacists to actively promote flu vaccines: Receiving an influenza vaccination is associated with a lower risk of major adverse cardiovascular events such as heart failure or hospitalization, especially in patients with existing heart disease.

The meta-analysis, published recently in the Journal of the American Medical Association, notes that the greatest risk reduction was seen among patients with recent acute coronary syndrome.

“Among nontraditional cardiovascular risk factors, there remains interest in a potential association between respiratory tract infections, of which influenza and influenza-like illnesses are common causes, and subsequent cardiovascular events,” according to background information in the article. It points out that several epidemiological studies have suggested a strong inverse relationship between influenza vaccination and the risk of fatal and nonfatal cardiovascular events.

To determine if influenza vaccination is associated with prevention of cardiovascular events, the researchers from the University of Toronto conducted a meta-analysis of all randomized clinical trials of influenza vaccine that studied cardiovascular events as efficacy or safety outcomes.

Six trials—five published and one unpublished—met inclusion criteria. Those involved 6,735 patients who were an average of 67-years-old, 51% female, 36% with a cardiac history and with follow-up of an average of 7.9 months. Researchers stratified analysis by subgroups of patients with and without a history of acute coronary syndrome (ACS) within 1 year of randomization.

Study authors report that, in the five published trials, 95 of 3,238 patients receiving influenza vaccine, 2.9%, developed a major adverse cardiovascular event within 1 year of follow-up compared with 151 of 3,231 patients, 4.7%, who did not receive the vaccine.

That represents an absolute risk difference favoring flu vaccine of 1.74%, according to the researchers, who add that addition of the unpublished data did not materially change the results—2.9% of patients who received influenza vaccine developed a major adverse cardiovascular event within 1 year versus 4.6% of patients who did not receive influenza vaccine.

A subgroup analysis suggests that patients with recent coronary artery disease especially benefit from influenza vaccination. Their risk of major adverse cardiovascular events after immunization was 10.3% compared to 23.1% placebo or control. Those with stable coronary artery disease did better with flu vaccination than placebo or control—6.9% risk compared to 7.4%—but the difference wasn’t nearly as great.

“Within this global meta-analysis of [randomized clinical trials] that studied patients with high cardiovascular risk, influenza vaccination was associated with a lower risk of major adverse cardiovascular events within one year,” study authors note. “Influenza vaccination was particularly associated with cardiovascular prevention in patients with recent ACS. Future research with an adequately powered multicenter trial to confirm the efficacy of this low-cost, annual, safe, easily administered, and well-tolerated therapy to reduce cardiovascular risk beyond current therapies is warranted.”

An accompanying editorial by Seattle, Washington–based Kathleen M. Neuzil, MD, MPH, of PATH, a nonprofit group promoting innovation in global health, points out that the recommendation of a pharmacist or other healthcare professional “is a strong predictor of vaccine acceptance and receipt among patients. While few are in a position to develop new influenza vaccines, all health care practitioners can recommend influenza vaccine to their patients. Doing so will help achieve the goal of 100% vaccination for the 2013-2014 influenza season.”

U.S. Pharmacist Social Connect