SNOWMASS, COLO. – The risk of herpes zoster isn’t raised in rheumatoid arthritis patients who are on a tumor necrosis factor inhibitor, compared with those on nonbiologic disease-modifying antirheumatic drugs, according to a preliminary analysis from by far the largest study to examine the question.
Findings from the same study also suggested that TNF–inhibiting therapy may actually protect against zoster in patients with psoriasis, psoriatic arthritis, ankylosing spondylitis, or inflammatory bowel disease.
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Dr. Kevin L. Winthrop
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Data from two previous, large, population-based studies looking at the risk of herpes zoster in RA patients on anti-TNF biologics reveal discordant conclusions. These conflicting findings prompted Dr. Kevin L. Winthrop and his coinvestigators in the SABER (Safety Assessment of Biologic Therapy) collaboration to examine the issue in their very large data set.
SABER is a retrospective cohort study involving four large U.S. automated health databases. The as-yet-unpublished SABER herpes zoster analysis included more than 35,000 patients with diseases for which TNF inhibitors are indicated.
During 22,215 person-years of follow-up, the crude rate of herpes zoster among RA patients who were new first-time users of an anti-TNF agent was 12.1 cases per 1,000 person-years, which wasn’t significantly different from the 12.8 per 1,000 rate during 7,165 person-years of follow-up in the control group, which comprised RA patients who were failing on methotrexate and adding another conventional DMARD, usually hydroxychloroquine (Plaquenil).
There were no significant differences in zoster rates among the various anti-TNF agents, Dr. Winthrop said at the symposium, which was sponsored by the American College of Rheumatology.
Intriguingly, going on an anti-TNF agent actually appeared to protect against herpes zoster in SABER participants with psoriasis, psoriatic arthritis, or ankylosing spondylitis. During 4,106 person-years of follow-up, their crude rate of zoster was 4.4 cases per 1,000 person-years, an adjusted 36% lower risk than that in patients on a nonbiologic DMARD, whose rate was 6.8 cases per 1,000 person-years during 3,950 person-years of follow-up, according to Dr. Winthrop, an infectious diseases specialist at Oregon Health and Science University, Portland.
Moreover, new users of infliximab or adalimumab for inflammatory bowel disease had an adjusted 20% reduction in risk of zoster, compared with those on azathioprine or 6-mercaptopurine, he added.
An earlier retrospective cohort study involving 20,357 RA patients in the Veterans Affairs health care system found that patients on adalimumab had an adjusted 47% lower risk of zoster, and those on etanercept had a 38% reduction in risk, compared with patients on conventional DMARDs. Patients on infliximab had a 30% increased risk; however, this trend didn’t reach statistical significance (Clin. Infect. Dis. 2009;48:1364-71).
In sharp contrast, investigators from the prospective German RABBIT registry involving 5,040 RA patients reported that adalimumab was associated with a 3-fold increased risk of herpes zoster compared to nonbiologic DMARD therapy. Infliximab had an adjusted 2.4-fold increased risk, which wasn’t statistically significant. Etanercept wasn’t associated with increased risk (JAMA 2009;301:737-44).
The explanation for the discordant findings in RABBIT and the VA study is unclear. The studies did use somewhat different methodologies. Regardless, it’s worth noting that the number of subjects included in the new SABER analysis was larger than for both of the earlier studies put together.
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