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Herpes zoster a 'potential trigger' for giant cell arteritis
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Although herpes zoster may increase the risk for giant cell arteritis, according to findings published in Arthritis and Rheumatology, antiviral treatment and vaccination did demonstrate any consistent benefit in reducing this risk.
The researchers, led by Bryant R. England, MD, of the University of Nebraska Medical Center, in Omaha, also concluded that the infrequency of herpes zoster in patients with giant cell arteritis (GCA) suggests that it is just one potential trigger for the condition.
“Giant cell arteritis is the most common systemic vasculitis, typically affecting elderly individuals,” England told Healio Rheumatology. “However, we don’t know the cause or triggering events that lead to GCA. Infections have been hypothesized to be triggers of GCA and there have been recent pathological studies that have identified varicella zoster virus, which causes shingles, in GCA temporal artery specimens. Because GCA is rare, we leveraged two, large, independent databases to identify herpes zoster events as a risk factor for GCA.”
The researchers added, “Moreover, if [herpes zoster] contributes to GCA risk, then it follows that antiviral therapy or vaccination could mitigate disease risk, effects that, to date, have not been investigated.”
To determine the epidemiologic association of herpes zoster events with incident GCA, the researchers conducted a retrospective cohort study of two large, independent datasets — the Medicare 5% random sample database, from Jan. 1, 2006, through Dec. 31, 2013, and the Truven Health Analytics MarketScan Commercial Claims and Encounters database, from Jan. 1, 2010, through Dec. 31, 2014. In total, there were 16,686,345 participants.
Eligible participants had 12 months of continuous coverage, were older than 50 years and had no prior history of GCA or polymyalgia rheumatica. The researchers identified complicated and uncomplicated herpes zoster events, as well as GCA, using ICD-9 codes from physician or hospital discharge records. In addition, they identified antiviral therapies and vaccinations from prescription claims and drug codes. Risk for incident GCA was calculated using multivariable Cox proportional hazards regression.
The researchers identified 5,942 GCA cases, with herpes zoster events occurring in 3.1% of the MarketScan group cases and in 6% of the Medicare group cases.
According to the researchers, unadjusted GCA incidence rates were highest among patients with complicated and uncomplicated herpes zoster. After completing multivariable adjustment, complicated herpes zoster was associated with an increased risk of GCA in the Medicare group (HR = 1.99; 95% CI, 1.32–3.02) and in the MarketScan group (HR = 2.16; 95% CI, 1.46–3.18). The researchers reported the same association regarding uncomplicated herpes zoster in the Medicare group (HR = 1.42; 95% CI 1.02–1.99) and the MarketScan group (HR = 1.45; 95% CI, 1.05–2.01).
“Herpes zoster appears to increase the risk of GCA, but does so in a minority of patients,” England said. “Thus, not all GCA is because of herpes zoster events, but it does appear that herpes zoster events might trigger GCA in a small proportion of patients.”
Vaccination and antiviral treatment were not consistently associated with GCA risk, according to the researchers. However, antiviral treatment was marginally associated with a decreased risk for GCA in the Medicare group (HR = 0.67; 95% CI, 0.46–0.99).
“We investigated whether anti-virals or vaccination for VZV was protective of GCA,” England said. “We did not find a consistent protective effect with either anti-virals or VZV vaccination, but the unstandardized nature in which these were prescribed, the low frequency of VZV vaccination, the reduced efficacy of the vaccine in the elderly — those most at risk of GCA — and weaning vaccine responses over time argue for further study.” – by Jason Laday
Disclosure: England reports funding from the Nebraska Arthritis Outcomes Research Center the the University of Nebraska Medical Center Mentored Scholars Program.
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