Herpes zoster and the risk of ischemic and hemorrhagic stroke: A systematic review and meta-analysis

BACKGROUND Herpes zoster infection and stroke are highly prevalent in the general population; however, reports have presented inconsistent findings regarding the relationship between herpes zoster infection and stroke. In this meta-analysis, we aimed to clarify this association. MATERIAL AND METHODS The PubMed and Embase databases were searched for studies published from their inception to January 2016. Two investigators independently extracted the data. The pooled relative risk (RR) was calculated using a random effects model. RESULTS A total of 8 studies met the inclusion criteria. During the first 1 month after herpes zoster infection, the pooled RRs for ischemic stroke and hemorrhagic stroke were 1.55 (95% CI, 1.46-1.65) and 1.70 (95% CI, 0.73-3.96), respectively, and within 3 months after infection, the corresponding RRs were 1.17 (95% CI, 1.12-1.23) and 2.05 (95% CI, 1.17-3.60), respectively. At 1 year and more than 1 year after herpes zoster infection, a significant relationship was not observed between herpes zoster infection and the incidence of ischemic and hemorrhagic stroke. Publication bias was not observed. CONCLUSION The accumulated evidence generated from this systematic review indicates that an increased risk for ischemic stroke occurred in the short term after herpes zoster infection, whereas a significant relationship was not observed in the long term after infection. With respect to hemorrhagic stroke, the association was not significant. With respect to hemorrhagic stroke, the association between was not significant except within 3 months after a herpes zoster infection.