From Diabetes in Control
Could Influenza Vaccination Prevent More Than Just the Flu?
Currently, only low-quality evidence exists to support efficacy of influenza vaccination to prevent seasonal influenza in patients with diabetes. There is even less information regarding the impact of influenza vaccination on cardiovascular events or all-cause mortality in this population. A recent study published in the Canadian Medical Association Journal was designed to evaluate the impact of seasonal influenza vaccination on admission to the hospital for acute myocardial infarction, stroke, heart failure, or pneumonia, and all-cause mortality in patients with type 2 diabetes.
Conducted over a 7-year time period from 2003 – 2009, the study analyzed retrospective patient data from the Clinical Practice Research Datalink in England. The analysis included 124,503 adult patients diagnosed with type 2 diabetes. At baseline, characteristics such as age, sex, smoking status, BMI, cholesterol labs, HbA1c, blood pressure, medications, and comorbidities were compared between patient groups. Vaccination rates of the included participants ranged from 63.1% to 69.0% per year. In general, unvaccinated participants were younger, had lower rates of pre-existing comorbidities, and were taking fewer medications.
The baseline characteristics of subjects enrolled in this retrospective analysis showed that sicker subjects received the flu vaccination more frequently. Given this observation, and seasonal confounding of flu outbreaks, data adjustments favored fewer cardiovascular events and lower rates of all-cause mortality during the influenza season spanning 7 years of data. While other studies have shown that influenza vaccination can reduce the risk of cardiovascular events in high-risk patients, this study is the first to demonstrate a reduction in cardiovascular events associated with influenza vaccination in patients with diabetes. This study is notable for its large sample size and long duration. However, given the retrospective nature of the study, further trials are warranted to offer conclusive evidence about the benefits of influenza vaccination in patients with diabetes.
- Previous clinical trials aimed at studying the effectiveness of the flu vaccine in patients with diabetes are often small, inconclusive, and have not investigated cardiovascular outcomes.
- When data was adjusted for baseline covariates and seasonal residual confounding, patients who received the influenza vaccination had significantly reduced rates of hospital admissions for stroke, heart failure, pneumonia or influenza, and all-cause mortality.
- Large experimental or quasi-experimental trials are needed to establish a causal link between influenza vaccination and clinical endpoints in patients with diabetes.
Vamos EP, Pape UJ, Curcin V, Harris DPhil MJ, Valabhji J, Majeed A, et al. Effectiveness of the Influenza vaccine in preventing admission to hospital and death in people with type 2 diabetes. CMAJ. 2016 July 25.
Remschmidt C, Wichmann O, Harder T. Vaccines for the prevention of seasonal influenza in patients with diabetes: systematic review and meta-analysis. BMC Med 2015;13:53.
Researched and prepared by Alysa Redlich, Pharm.D. Candidate, University of Rhode Island, reviewed by Michelle Caetano, Pharm.D., BCPS, BCACP, CDOE, CVDOE