Shingles is linked to increased risk of cardiovascular events

A patient’s risk of stroke and myocardial infarction may increase in the six months after herpes zoster infection (shingles), research published in PLOS Medicine has shown.1

The self controlled case series analysis looked at 42 954 US Medicare beneficiaries aged 65 or older who had had a herpes zoster diagnosis and an ischaemic stroke, as well as 24 237 beneficiaries who had had herpes zoster and a myocardial infarction, during a five year period. The researchers, from the London School of Hygiene and Tropical Medicine, UK, then calculated the rates of stroke and myocardial infarction at different times after herpes zoster compared with unexposed time periods within individual patients.

The most marked increase was seen during the first week after zoster diagnosis: a 2.4-fold increased rate of ischaemic stroke (age adjusted incidence ratio 2.37 (95% confidence interval 2.17 to 2.59)) and a 1.7-fold increased rate of myocardial infarction (incidence ratio 1.68 (1.47 to 1.92)). This increase then gradually tailed off over six months.

The study found no evidence that the incidence of myocardial infarction or stroke varied depending on whether patients had been vaccinated against zoster. However, only 9% of the study participants had been vaccinated, which limited the study’s power to detect an effect of vaccination.

The researchers said that previous studies had used cohort designs that were vulnerable to confounding, owing to inherent differences between patients who develop zoster and those who do not. They said that their within-person study design limited such confounding.

The authors concluded, “The rapid increase in the rate of acute cardiovascular events after zoster diagnosis, followed by gradual resolution, is supportive of a causative association.”

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