Serious Infections Increased in Etanercept-Treated Juvenile Arthritis Patients Save

UK researchers set out to study medically significant infections (MSI) in juvenile idiopathic arthritis patients enrolled in the British Society for Paediatric and Adolescent Rheumatology Etanercept Cohort Study (BSPAR-ETN).  They compared the rates of MSI in those receiving ETN alone versus MTX alone versus ETN plus methotrexate (MTX).

A total of 1,112 patients were included in this analysis (852 receiving ETN and 260 receiving MTX), including 14 patients who had discontinued ETN prior to enrolling with the study. The mean followup time on medication was 2.6 years in the ETN cohort and 3.0 years in the MTX cohort. Although the ETN cohort was older and hand more overall comorbidities (uveitis10%, eczema 8%, asthma 8%),disease activity measures were the same between groups.

There were 33 first MSIs were reported (109 with ETN and 24 with MTX). The incidence of MSIs was 4.8 per 100 person-years (PY) (95% CI 4.0–5.6). ETN-treated patients showed an increase in the rate of MSIs, with a crude incidence rate of 5.5 per 100PY (95% CI 4.5–6.6) versus 3.4 per 100 PY (95% CI 2.2–5.0) for MTX. JIA patients on ETN had higher MSI rates (adjusted hazard ratio 2.13 [95% CI  1.22–3.74]). The risk of MSI was higher regardless if patients were receiving combination or monotherapy with ETN. 

Sensitivity analysis showed no between-group difference in the rate of serious infections (SIEs), which were much less common. Both MSI and SIE definitions included those with infections that were 1) life-threatening, 2) caused significant disability, 3) caused death, 4) led to hospitalization, or 5) required intravenous antibiotics, but only MSI could be declared if deemed “medically significant” by the consultant.

British Society for Paediatric and Adolescent Rheumatology Etanercept Cohort Study is a study of those treated with ETN versus those treated with MTX and is supported by a research grant from BSPAR to the University of Manchester. BSPAR has received restricted income from Pfizer that finances an entirely separate contract between BSPAR and the University of Manchester to provide and oversee the data collection and analysis as well as the management of the study.