Influenza vaccination provides survival gains in patients with heart failure
Patients with heart failure may benefit from receiving flu shots, which reduce the risk of both all-cause and cardiovascular death, as shown in a recent study from Denmark.
Annual influenza vaccination, a greater cumulative number of vaccinations and vaccination early in the year are all associated with larger reductions in the risk of both cardiovascular and all-cause death compared with less frequent vaccination and vaccination later in the year, the authors said.
“[Therefore], annual influenza vaccination may be an effective treatment strategy to improve survival in heart failure,” they added.
The Danish cohort study included 134,048 heart failure patients (mean age 73.3 years; 55.9 percent male). A total of 77,956 patients (58 percent) died of all causes and 47,966 (36 percent) died of cardiovascular causes over a median follow-up of 3.7 and 3.3 years, respectively. The vaccination coverage ranged between 16 percent and 54 percent during the study period.
In multivariable Cox regression models, receipt of ≥1 vaccination led to an 18-percent reduction in the risk of death (all-cause and cardiovascular causes: hazard ratio [HR], 0.82; 95 percent CI, 0.81–0.84; p<0.001). [Circulation 2018;doi:10.1161/CIRCULATIONAHA.118.036788]
The cumulative number of vaccinations was significantly associated with lower risks of all-cause and cardiovascular death, such that receiving >3 vaccines after heart failure diagnosis conferred the greatest protection as compared with nonreceipt (HR, 0.72; 0.70–0.73 and HR, 0.71; 0.69–0.74, respectively; p<0.001 for both).
Annual vaccination also provided larger reductions in the risk of death (all-cause: HR, 0.81; 0.80–0.83; cardiovascular: HR, 0.81; 0.79–0.83; p<0.001 for both) than did less frequent vaccination (all cause: HR, 0.87; 0.85–0.90; cardiovascular: HR, 0.92; 0.89–0.96; p<0.001 for both) compared with nonreceipt.
Finally, vaccination early in the year (September and October) was associated with greater protection against a poor outcome compared with late vaccination (November and December; p<0.001 for trend).
“Vaccination early in the season may be more efficient for preventing influenza infection because the patient is allowed less time during the season to contract influenza before vaccination. Thus, it may be beneficial to administer the vaccine as early in the season as possible,” the authors explained.
“[Also], an influenza infection may exacerbate heart failure symptoms and possibly advance the progression of the disease. Thus, if multiple episodes of infection are prevented by multiple vaccinations, it is possible that the patient is spared unnecessary disease progression caused by multiple influenza infections, and this may explain in part why a greater cumulative number of vaccinations was associated with greater reductions in mortality,” they added.
Despite the presence of several limitations, the present study points to the potential of flu shots–a safe, low-cost, highly effective strategy for reducing influenza-related morbidity–for improving outcome in patients with heart failure.
“Influenza vaccination should be considered as a potential treatment strategy comparable to other medical treatments such as β-blockers and angiotensin-converting enzyme inhibitors... Emphasizing this in future heart failure guidelines would encourage vaccination of patients with heart failure and likely improve patient survival,” the authors said.