A meta-analysis of stroke risk following herpes zoster infection

BACKGROUND The incidence of herpes zoster (HZ) is increasing and poses a significant health concern to aging populations. Several studies suggest an increased risk of stroke following zoster infection, but the results are conflicting. We conducted a systematic review and meta-analysis to determine if stroke risk is increased following HZ infection. METHODS A search of MEDLINE, EMBASE, Google scholar, Web of Science, CAB Direct, Cumulative Index to Nursing and Allied Health Literature, and Evidence Based Medicine Reviews was conducted for observational studies of adults with HZ infection that examined stroke and TIA risk from January 1, 1966 to May 31, 2016. Adjusted relative risks reported for similar follow-up durations were pooled across studies separately using random-effects inverse variance models. RESULTS Data were pooled from nine studies. Relative risk for stroke after zoster was 1.78 (95% CI 1.70-1.88) for the first month following herpes zoster, dropping progressively to 1.43 (95% CI 1.38-1.47) after 3 months, to 1.20 (95% CI 1.14-1.26) after 1 year. We found that stroke risk increases by a larger margin during the first month after a herpes zoster ophthalmicus episode: relative risk 2.05 (95% CI 1.82-2.31). The risk remains elevated one year after the acute episode. CONCLUSIONS Herpes zoster is an established risk factor for increasing the risk of stroke, especially shortly after infection. Vaccination should be encouraged in patients at high risk of cardiovascular disease.