Influenza Vaccination is Associated with Reduced Cardiovascular Mortality in Adults with Diabetes. A Nationwide Cohort Study
Methods: We used nationwide register data to identify DM patients in Denmark during 9 consecutive influenza seasons in the period 2007-2016. DM was defined as use of glucose-lowering medication. Patients who were not 18-100 years old or had ischemic heart disease, heart failure, chronic obstructive lung disease, cancer or cerebrovascular disease were excluded. Patient exposure to influenza vaccination was assessed prior to each influenza season. We considered outcomes death from all causes, from cardiovascular causes and death from AMI or stroke. For each season, patients were followed from December 1 until April 1 the next year.
Results: A total of 241,551 Patients were followed for a median of 4 seasons (interquartile range: 2-8 seasons) for a total follow-up of 425,318 person-years. The vaccine coverage during study seasons ranged from 24% to 36%. During follow-up, 8,207 patients died of all-causes (3.4%), 4,127 patients died of cardiovascular causes (1.7%) and 1,439 patients died of AMI/stroke (0.6%). After adjustment for confounders, vaccination was significantly associated with reduced risks of all-cause death (HR 0.83, p<0.001), cardiovascular death (HR 0.84, p<0.001), death from AMI or stroke (HR 0.85, p=0.028) and a reduced risk of being admitted to hospital with acute complications associated with DM (diabetic ketoacidosis, hypoglycemia or coma) (HR 0.89, p=0.006).
Conclusion: In patients with DM, influenza vaccination was associated with a reduced risk of death, cardiovascular death and death from AMI or stroke. Influenza vaccination may improve outcome in patients with DM.