title: Acute Cardiovascular Events after Herpes Zoster: A Self-Controlled Case Series Analysis in Vaccinated and Unvaccinated Older Residents of the United States.
abstract: BACKGROUND
  Herpes zoster is common and can have serious consequences. Additionally, emerging data suggest an increased risk of acute cardiovascular events following herpes zoster. However, to our knowledge, existing association studies compare outcomes between individuals and are therefore vulnerable to between-person confounding. In this study, we used a within-person study design to quantify any short-term increased risk of acute cardiovascular events (stroke and myocardial infarction [MI]) after zoster and to assess whether zoster vaccination modifies this association.
  
  
  RESULTS
  The self-controlled case series method was used to estimate rates of stroke and acute MI in defined periods after herpes zoster compared to other time periods, within individuals. Participants were fully eligible Medicare beneficiaries aged ≥ 65 y with a herpes zoster diagnosis and either an ischemic stroke (n = 42,954) or MI (n = 24,237) between 1 January 2006 and 31 December 2011. Age-adjusted incidence ratios (IRs) for stroke and MI during predefined periods up to 12 mo after zoster relative to unexposed time periods were calculated using conditional Poisson regression. We observed a marked increase in the rate of acute cardiovascular events in the first week after zoster diagnosis: a 2.4-fold increased ischemic stroke rate (IR 2.37, 95% CI 2.17-2.59) and a 1.7-fold increased MI rate (IR 1.68, 95% CI 1.47-1.92), followed by a gradual resolution over 6 mo. Zoster vaccination did not appear to modify the association with MI (interaction p-value = 0.44). We also found no evidence for a difference in the IR for ischemic stroke between vaccinated (IR 1.14, 95% CI 0.75-1.74) and unvaccinated (IR 1.78, 95% CI 1.68-1.88) individuals during the first 4 wk after zoster diagnosis (interaction p-value = 0.28). The relatively few vaccinated individuals limited the study's power to assess the role of vaccination.
  
  
  CONCLUSIONS
  Stroke and MI rates are transiently increased after exposure to herpes zoster. We found no evidence for a role of zoster vaccination in these associations. These findings enhance our understanding of the temporality and magnitude of the association between zoster and acute cardiovascular events.
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, United Kingdom.
authors.forename: Caroline
authors.initials: C
authors.lastname: Minassian
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, United Kingdom.
authors.forename: Sara L
authors.initials: SL
authors.lastname: Thomas
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, United Kingdom.
authors.forename: Liam
authors.initials: L
authors.lastname: Smeeth
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, United Kingdom.
authors.forename: Ian
authors.initials: I
authors.lastname: Douglas
authors.affiliation: Department of Health Services and Population Research, Kings College London, London, United Kingdom.
authors.forename: Ruth
authors.initials: R
authors.lastname: Brauer
authors.affiliation: Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, United Kingdom.
authors.forename: Sinéad M
authors.initials: SM
authors.lastname: Langan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006562:Herpes Zoster / Q000150:complications* / Q000453:epidemiology*; D053061:Herpes Zoster Vaccine / Q000009:adverse effects*; D014645:Herpesvirus 3, Human / Q000502:physiology; D006801:Humans; D015994:Incidence; D008297:Male; D006278:Medicare; D009203:Myocardial Infarction / Q000453:epidemiology* / Q000209:etiology* / Q000821:virology; D020521:Stroke / Q000453:epidemiology* / Q000821:virology; D014481:United States / Q000453:epidemiology
chemical_list: D053061:Herpes Zoster Vaccine