Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


The Incidence of Herpes Zoster in Seniors with Rheumatoid Arthritis.

Widdifield7,  Jessica, Bernatsky2,  Sasha R., Paterson1,  J. Michael, Gunraj1,  Nadia, Pope5,  Janet E., Thorne4,  J. Carter, Cividino3,  Alfred A.

Institute for Clinical Evaluative Science
McGill UHC/RVH, Montreal, QC, Canada
McMaster University, Hamilton, ON, Canada
Southlake Regional Health Care, Newmarket, ON, Canada
St Joseph Health Care London, London, ON, Canada
University of Toronto, Toronto, ON, Canada
University of Toronto

Herpes zoster (HZ) is a painful cutaneous eruption caused by varicella-zoster reactivation. It results in substantial morbidity, particularly in elderly and/or immunocompromised patients. Recent literature suggests that patients with rheumatoid arthritis (RA) are at particular risk for HZ. The Ontario Biologics Research Initiative (OBRI) conducts real-world surveillance through administrative database linkage with primary data collection, based in Canada's largest province (population > 13 million).

Purpose:

To study risk and risk factors for HZ, using a case-control sample nested within a cohort of seniors with RA.

Methods:

An RA cohort was assembled from Ontario billing, hospitalization and prescription data, 1992–2008. Analyses were limited to subjects aged >65 who filled >= 1 prescription for a disease-modifying agent (DMARD), oral corticosteroid, or biologic. We studied cases of HZ identified from physician billing and hospitalization diagnoses over 1998–2009. RA controls (age, sex and time matched) were randomly selected by risk-set sampling. Multivariate conditional logistic regression assessed the independent effects of concomitant drug treatments on HZ, adjusted for demographics, co-morbidity, and markers of RA severity (rheumatology visits, extra-articular RA features, joint replacement).

Results:

A total of 3,999 cases of HZ were recorded among 85,458 seniors with RA during 614,915 person-years (6.5 events/1000 person-years). Comparing these HZ cases to 19,995 RA controls, 21.9% of cases versus 10.8% of controls were exposed to prednisone at the time of infection. Multivariate models demonstrated that risk of HZ was higher among current and past use of all DMARD groups. There was a notable increasing trend for higher risk of HZ with increasing steroid doses. Due to low rates of biologic drug exposures in our sample, the estimated effects of these agents were imprecise, but also consistent with a higher risk.

Conclusions:

Our estimates emphasize an association of anti-rheumatic therapies with the occurrence of HZ. Potential limitations of our study include the possibility of incomplete ascertainment of biologic exposures (private insurance is not represented in public payer database; but this is uncommon) and channelling bias (where persons at highest risk for infections may not be prescribed biologics).

Drug ExposureAdjusted Odds Ratio [95% Confidence Interval]
Anti-TNF agent [REF = Non-user] 
  Current use1.17 [0.63 2.19]
  Past use1.54 [0.68 3.51]
Anti-IL1 [REF = Non-user] 
  Current use4.02 [0.54 29.63]
  Past use
Methotrexate [REF = Non-user] 
  Current use1.44 [1.27 1.62]
  Past use1.28 [1.08 1.52]
Sulfasalazine [REF = Non-user] 
  Current use1.01 [0.77 1.34]
  Past use0.92 [0.66 1.29]
Leflunomide [REF = Non-user] 
  Current use1.46 [1.03 2.06]
  Past use1.16 [0.73 1.84]
Hydroxychloroquine [REF = Non-user] 
  Current use1.89 [1.68 2.13]
  Past use1.25 [1.05 1.49]
Cyclophosphamide [REF = Non-user] 
  Current use8.35 [1.50 46.58]
  Past use1.90 [0.57 6.27]
Azathioprine [REF = Non-user] 
  Current use1.79 [1.18 2.73]
  Past use1.24 [0.69 2.25]
NSAIDs/COXIBs [REF = Non-user] 
  Current use1.72 [1.57 1.89]
  Past use1.55 [1.42 1.70]
Other DMARDs [REF = Non-user] 
  Current use1.73 [1.28 2.33]
  Past use1.15 [0.83 1.60]
Steroid Use [REF = None] 
  Low <=5 mg prednisone equivalent/day1.66 [1.45 1.91]
  Medium 6–9 mg/day1.91 [1.46 2.50]
  High 10–19 mg/day1.99 [1.67 2.37]
  Very High >= 20 mg/day3.22 [2.66 3.89]
  Past use1.29 [1.17 1.42]

To cite this abstract, please use the following information:
Widdifield, Jessica, Bernatsky, Sasha R., Paterson, J. Michael, Gunraj, Nadia, Pope, Janet E., Thorne, J. Carter, et al; The Incidence of Herpes Zoster in Seniors with Rheumatoid Arthritis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :341
DOI: 10.1002/art.28110

Abstract Supplement

Meeting Menu

2010 ACR/ARHP