Risk of stroke following herpes zoster: a self-controlled case-series study.
BACKGROUND
Herpes zoster is common and vaccine preventable. Stroke risk may be increased following zoster, but evidence is sparse and could be explained by differences between people with and without zoster. Our objective was to determine if stroke risk is increased following zoster.


METHODS
Within-person comparisons were undertaken using the self-controlled case-series method and data from the UK Clinical Practice Research Datalink (1987-2012). Participants had a first-ever diagnosis of zoster and stroke within the study period. Stroke incidence in periods following zoster was compared with incidence in other time periods. Age-adjusted incidence ratios (IRs) and 95% confidence intervals (CIs) were calculated.


RESULTS
A total of 6584 individuals were included. Stroke rate was increased following zoster compared with the baseline unexposed period, then gradually reduced over 6 months: weeks 1-4 (age-adjusted IR, 1.63; 95% CI, 1.32-2.02), weeks 5-12 (IR, 1.42; 95% CI, 1.21-1.68), and weeks 13-26 (IR, 1.23; 95% CI, 1.07-1.42), with no increase thereafter. A stronger effect was observed for individuals with zoster ophthalmicus, rising to a >3-fold rate 5-12 weeks after zoster. Oral antivirals were given to 55% of individuals: IRs for stroke were lower among those receiving antivirals compared with those not treated, suggesting a protective effect.


CONCLUSIONS
We have established an increased stroke rate within 6 months following zoster. Findings have implications for zoster vaccination programs, which may reduce stroke risk following zoster. The low antiviral prescribing rate needs to be improved; our data suggest that antiviral therapy may lead to a reduced stroke risk following zoster.
Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, United Kingdom.
Sinéad M
SM
Langan
Caroline
C
Minassian
Liam
L
Smeeth
Sara L
SL
Thomas
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000998:Antiviral Agents / Q000627:therapeutic use; D005260:Female; D006562:Herpes Zoster / Q000150:complications* / Q000188:drug therapy; D006801:Humans; D015994:Incidence; D008297:Male; D018570:Risk Assessment; D020521:Stroke / Q000453:epidemiology*; D013997:Time Factors; D006113:United Kingdom / Q000453:epidemiology
D000998:Antiviral Agents
herpes zoster; self-controlled case-series study; stroke