RESEARCH - Rates and risk factors for herpes zoster in patients with RA

April 3, 2006

RATES AND RISK FACTORS FOR HERPES ZOSTER IN PATIENTS WITH RHEUMATOID

ARTHRITIS

F. Wolfe, K. Michaud: Wichita, United States

The prevalence and incidence of Herpes zoster infection in RA is unknown.

The purpose of this study was to investigate whether H. zoster infection

rates are increased in RA, and whether RA specific therapies (particularly

TNF inhibitors) increase the risk of H. zoster infection in persons with RA.

Methods: Participants enrolled in the National Data Bank for Rheumatic

Diseases were queried in mailed questionnaires at 6 month intervals over a

five year period. Incident H. zoster infection was determined by patient

self-report as ever infection (based on first report at any time within

enrollment in the Data Bank) or infection within the last 6 months

(identified by specific query, as above). Predictive models using lagged

variables in 6-month intervals were constructed using regression, linear

regression, and generalized estimating equations (GEE) regression.

Results: 17,827 RA patients were included (mean age 61 years, median disease

duration 12 years) compared to 3112 OA patients (mean age 63 years). The

lifetime prevalence of H. zoster infection among RA patients was 15.2 per

100 compared with 16.9 per 100 in OA patients. However, after adjusting for

age, an important confounding variable in H. zoster infection, the lifetime

prevalence of H. zoster infection among RA patients was 15.0 per 100

compared to 14.4 per 100 in OA patients. The overall annual incidence rate

of H. zoster infection in RA patients was 2.8 cases per 100 patient years

and increased with increasing age, with an annual incidence rate of 1.7

cases per 100 patient years for ages 20-30 years compared to 3.1 cases per

100 patient years for ages 60-70 years.

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