Etanercept improves linear growth and bone mass acquisition in MTX-resistant polyarticular-course juvenile idiopathic arthritis.
OBJECTIVE
Chronic inflammation in juvenile idiopathic arthritis interferes with linear growth and bone mass acquisition. We prospectively evaluated and compared linear growth and evolution of bone mass acquisition and body composition in MTX-resistant polyarticular-course JIA (polyJIA) patients started on etanercept and in recently diagnosed polyJIA patients started on MTX monotherapy.


METHODS
Sixteen MTX-resistant polyJIA patients were given add-on etanercept, eight recently diagnosed polyJIA patients were started on MTX. Patients were evaluated at baseline and at 1, 6, 12 and 18 months with respect to disease activity, linear growth, BMD and body composition.


RESULTS
Baseline patient and disease characteristics were similar in both groups. Clinical disease activity (Pediatric ACR30) was equally well controlled in both groups. Growth velocity increased significantly allowing catch-up growth in the etanercept + MTX group only. BMD (lumbar spine Z-score) improved significantly in both groups. A significant increase of bone mineral content and lean:fat mass ratio was seen in the etanercept + MTX group, but not in the MTX group.


CONCLUSIONS
Clinical control of disease activity by etanercept in MTX-refractory polyJIA is associated with rapidly instituted catch-up growth and improvement of bone mineralization and body composition. In recently diagnosed polyJIA patients treated with MTX the relation between clinical response and these parameters was less evident. Preliminary data on serum IL-6 and osteoprotegerin levels indicate that the beneficial effects seen with etanercept therapy may be related to its control of systemic IL-6 production and enhancement of osteoblast activity.
Billiau
An D
AD
Laboratory of Experimental Transplantation, University of Leuven, Leuven, Belgium.
Loop
Michèle
M
Le
Phu-Quoc
PQ
Berthet
Françoise
F
Philippet
Pierre
P
Kasran
Ahmad
A
Wouters
Carine H
CH
D000293:Adolescent; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001171:Arthritis, Juvenile / Q000188:drug therapy* / Q000503:physiopathology; D015519:Bone Density / Q000187:drug effects*; D002648:Child; D002675:Child, Preschool; D004351:Drug Resistance; D000068800:Etanercept; D005260:Female; D006128:Growth / Q000187:drug effects*; D006801:Humans; D007074:Immunoglobulin G / Q000627:therapeutic use*; D008297:Male; D008727:Methotrexate / Q000627:therapeutic use*; D011446:Prospective Studies; D018124:Receptors, Tumor Necrosis Factor / Q000627:therapeutic use*; D013223:Statistics as Topic; D013997:Time Factors; D016896:Treatment Outcome
D018501:Antirheumatic Agents; D007074:Immunoglobulin G; D018124:Receptors, Tumor Necrosis Factor; D000068800:Etanercept; D008727:Methotrexate