RESEARCH - Initiation of RA treatments and the risk of serious infections

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Rheumatology Advance Access published online on November 11, 2009

Rheumatology, doi:10.1093/rheumatology/kep325

Initiation of rheumatoid arthritis treatments and the risk of serious infections

G. Grijalva1, Kaltenbach2, G. Arbogast1,2,

F. Mitchel, Jr1 and Marie R. 1,3,4

1Department of Preventive Medicine, Center for Education and Research

on Therapeutics, 2Department of Biostatistics, 3Department of

Medicine, Vanderbilt University School of Medicine and 4Mid-South

Geriatric Research Education and Clinical Center, VA TN Valley Health

Care System, Nashville, TN, USA

Abstract

Objective. In clinical trials of RA patients on traditional DMARDs,

the addition of TNF- antagonists increased infections compared with

addition of placebo. Our objective was to compare serious infections

following initiation of different RA regimens. Prior comparative

studies of DMARD initiation have yielded conflicting results.

Methods. We estimated hospitalization rates for infections following

initiation of TNF- antagonists, other DMARDs and oral glucocorticoids

in Tennessee Medicaid-enrolled RA patients (1995–2005). Exposure time

was measured using pharmacy information and infections were identified

using validated definitions. Initiation of RA regimens was compared

using regression models with MTX as the reference. Sensitivity

analyses excluded glucocorticoid users, applied a first exposure

carried forward approach, restricted observations to 2002–05 and first

episodes of use and explored effects of unmeasured confounders.

Results. We identified 28 906 new episodes of medication use,

including TNF- antagonists (8%), MTX alone (15%) and glucocorticoids

alone (57%). Compared with MTX initiation, TNF- antagonist initiation

did not significantly increase the risk of hospitalizations for

pneumonia [adjusted hazard ratio (aHR) 1.61; 95% CI 0.85, 3.03] or any

infection (aHR 1.31; 95% CI 0.78, 2.19). Initiation of LEF, SSZ or HCQ

did not increase serious infections, compared with MTX. Both

initiation and concurrent glucocorticoid use were associated with a

dose-dependent increase in serious infections. Sensitivity analyses

showed consistent results.

Conclusions. Compared with initiation of MTX alone, initiation of TNF-

antagonists was not associated with a large increase in the risk of

serious infections. Glucocorticoid use was associated with a

dose-dependent increase in the risk of these infections.

http://rheumatology.oxfordjournals.org/cgi/content/abstract/kep325v1?papetoc

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