HONOLULU – according to findings from a retrospective study of Medicare beneficiaries with shingles and ischemic stroke.
Dr. Quanhe Yang
The findings suggest that primary prevention of shingles through vaccination might be the most effective approach to prevent shingles-associated acute ischemic stroke, said the researchers, who presented the study at the International Stroke Conference sponsored by the American Heart Association.
Almost one in three people in the United States will develop shingles, also known as herpes zoster, in their lifetime, according to the Centers for Disease Control and Prevention. Previous research has not simultaneously examined the effect of shingles vaccination and antiviral treatment following shingles onset on the risk of acute ischemic stroke.
Quanhe Yang, PhD, a senior scientist at the CDC, and his colleagues examined data for 35,186 Medicare fee-for-service beneficiaries who were 66 years or older, diagnosed with shingles during 2008-2014, and diagnosed with acute ischemic stroke within a year of shingles diagnosis. Using a self-controlled case series design, the investigators analyzed the association between shingles and stroke. Dr. Yang and his colleagues estimated the incident rate ratio (IRR) by comparing the incidence of stroke during risk periods (i.e., periods following shingles), compared with control periods. To minimize confounding by age, they restricted their analyses to approximately 365 days from the shingles index date.
To investigate how vaccination against shingles with Zostavax and antiviral treatment following shingles affected stroke risk, the researchers classified beneficiaries into the following four groups: Group 1 had no vaccination and no antiviral treatment (49% of beneficiaries), Group 2 had vaccination only (9%), Group 3 had antiviral treatment only (34%), and Group 4 had vaccination and antiviral treatment (8%). The researchers tested for interaction to examine the changes in IRRs across the four groups.
IRRs for stroke progressively declined as time passed from the index shingles date, from 1.61 at 0-14 days following shingles to 1.35 at 15-30 days, 1.16 at 31-90 days, and 1.05 at 91-180 days. The researchers found no evidence that shingles vaccination and antiviral treatment modified the risk of acute ischemic stroke. The association between shingles and risk for acute ischemic stroke was consistent across age groups (i.e., 66-74 years, 75-84 years, and 85 years or older), sex, and race (i.e., non-Hispanic white, non-Hispanic black, and Hispanic, other).
One of the study’s strengths was that its sample was a large national cohort of Medicare fee-for-service beneficiaries, Dr. Yang said. In addition, the study design eliminated all fixed confounding effects. Potential weaknesses, however, included the fact that herpes zoster diagnosis was based on administrative data and that the vaccine’s efficacy declines over time.
The findings suggest that the importance of following the recommended shingles vaccination protocol in the prevention of shingles, Dr. Yang said. Shingrix, a vaccine that the Food and Drug Administration approved in 2017, prevents shingles with an efficacy greater than 90%, he added.
The investigators reported no funding source or disclosures for this study.
SOURCE: Yang Q et al. Circulation. 2019;50(Suppl_1): Abstract 39