RESEARCH - Time-dependent increase in risk of hospitalization with infection among RA patients treated with TNF antagonists

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Ann Rheum Dis. Published Online First: 29 January 2007.

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Extended Report

Time-dependent increase in risk of hospitalisation with infection among

swedish ra-patients treated with tnf- antagonists

Johan Askling 1*, C Fored 2, Lena Brandt 2, Eva Baecklund 3, Lennart

Bertilsson 4, Nils Feltelius 5, Lars Cöster 6, Pierre Geborek 7, Lennart T

sson 7, Staffan Lindblad 1, Jörgen Lysholm 8, Solbritt

Rantapää-Dahlqvist 9, Tore Saxne 7, F van Vollenhoven 1 and Lars

Klareskog 1

Abstract

Objectives: The degree to which treatment with TNF-antagonists may be

associated with increased risks for serious infections is unclear. We

performed an observational cohort study using prospectively collected data

from the Swedish Biologics Register (ARTIS) and other national Swedish

registers.

Methods First, in the Swedish biologics register (ARTIS) we identified all

4,167 RA-patients starting TNF- antagonist treatment between 1999 and 2003.

Second, in the Swedish Inpatient Register, we identified all individuals

hospitalized for any reason and who also carried a diagnosis of RA, between

1964 and 2003 (n=44,946 of whom 2,692 also occurred in ARTIS). Thirdly, in

the Swedish Inpatient Register, we identified all hospitalisations listing

an infection between 1999 and 2003. By cross-referencing these three

data-sets, we calculated relative risks (RR) for hospitalisation with

infection associated with TNF- antagonist treatment within the cohort of

44,946 RA patients, using regression taking age sex, age, geography,

co-morbidity, and use of inpatient care into account.

Results Among the 4,167 patients treated with TNF- antagonists, 367

hospitalizations with infections occurred during 7,776 person-years. Within

the cohort of 44,496 RA patients, the relative risk for infection associated

with TNF-antagonists was 1.43 (95%CI 1.18- 1.73) during the first year of

treatment, 1.15 (95% CI 0.88-1.51) during the second year of treatment, and

0.82 (95% CI 0.62-1.08) for subjects remaining on their first TNF-antagonist

treatment after two years.

Conclusion Treatment with TNF-antagonists may be associated with a small to

moderate increase in risk of hospitalization with infection, which

disappears with increasing treatment duration.

http://ard.bmj.com/cgi/content/abstract/ard.2006.062760v1?papetoc

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