RESEARCH - Herpes zoster risk factors in a national cohort of veterans with RA

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Clin Infect Dis. 2009 May 15;48(10):1364-71. Links

Herpes zoster risk factors in a national cohort of veterans with

rheumatoid arthritis.

Mc JR, Zeringue AL, Caplan L, Ranganathan P, Xian H, Burroughs

TE, Fraser VJ, Cunningham F, Eisen SA.

St. Louis Veterans Affairs Medical Center, St. Louis, Missouri 63106, USA.

BACKGROUND: Herpes zoster occurs more commonly in patients taking

immunosuppressive medications, although the risk associated with

different medications is poorly understood.

METHODS: We conducted a retrospective cohort study involving 20,357

patients who were followed in the Veterans Affairs healthcare system

and treated for rheumatoid arthritis from October 1998 through June

2005. proportional hazards regression was used to determine risk

factors for herpes zoster and herpes zoster-free survival. Chart

review was performed to validate the diagnosis of herpes zoster.

RESULTS: The incidence of herpes zoster was 9.96 episodes per 1000

patient-years. In time-to-event analysis, patients receiving

medications used to treat mild rheumatoid arthritis were less likely

to have an episode of herpes zoster than patients receiving

medications used to treat moderate and severe rheumatoid arthritis (P

< .001). Independent risk factors for herpes zoster included older

age, prednisone use, medications used to treat moderate and severe

rheumatoid arthritis, malignancy, chronic lung disease, renal failure,

and liver disease. Among patients receiving tumor necrosis

factor-alpha antagonists, etanercept (hazard ratio, 0.62) and

adalimumab (hazard ratio, 0.53) were associated with a lower risk of

herpes zoster. There was excellent agreement between the International

Classification of Diseases, Version 9, Clinical Modification diagnosis

of herpes zoster and diagnosis by chart review (kappa = 0.92).

CONCLUSIONS: Risk factors for herpes zoster included older age,

prednisone use, medications used to treat moderate and severe

rheumatoid arthritis, and several comorbid medical conditions. These

results demonstrate that the Department of Veterans Affairs' national

administrative databases can be used to study rare adverse drug

events.

PMID: 19368499

http://www.ncbi.nlm.nih.gov/pubmed/19368499

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