Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.


Body Mass Index Is Associated with Decreased Response to Initial and Delayed Treatment with Dose Escalated Infliximab in Patients with Recent Onset Rheumatoid Arthritis.

Heimans1,  L., van den Broek1,  M., Dirven1,  L., Schouffoer1,  A.A., Speyer2,  I., Kerstens3,  P.J.S.M., Huizinga4,  T.W.J.

Leiden University Medical Center, Leiden, Netherlands
Bronovo Hospital, Den Haag, Netherlands
Jan van Breemen Research Institute|Reade, Amsterdam, Netherlands
Leiden University Medical Centre, Leiden, Netherlands
VU University medical center, Amsterdam, Netherlands

Background/Purpose:

Patients with established RA with a high Body Mass Index (BMI) respond less well to delayed treatment with a fixed dose of TNF-blocker infliximab (IFX).1 The aim of this study was to assess the relationship between BMI and the response to initial and delayed treatment with IFX with dose escalation to a maximum of 10 mg/kg in recent onset RA patients treated according to a disease activity score (DAS) steered treatment protocol.

Methods:

In a post-hoc analysis of the BeSt study, outcome of treatment with IFX and methotrexate (MTX) was assessed and compared between BMI-categories. (table 1) Initial treatment with IFX (3mg/kg/8 weeks, after a loading dose) and MTX was started in 120 patients. In addition, in 109 patients, IFX and MTX were started after they had failed on 3 treatment steps with disease modifying antirheumatic drugs (DMARDs). In case of insufficient response (DAS >2.4), the IFX dose was increased to 6, then 7.5 and a maximum of 10 mg/kg. Adequate response to IFX was defined as having a DAS <=2.4 for at least 6 months on the IFX initial dose of 3 mg/kg. Failure to respond was defined as being assigned to another treatment regimen because of insufficient response to the maximum IFX dose. Response could be defined as adequate or insufficient in 143 patients. The association between BMI and failing to respond to IFX was assessed with multivariate regression analyses, adjusted for baseline DAS, age, sex, smoking, and anti-citrullinated protein antibody (ACPA)-status.

Results:

Outcome of treatment could be defined in 143 patients, of whom 96 received IFX as initial treatment. Patients were categorized as having a normal BMI (<25), being overweight (BMI >25 but <30) or being obese (BMI >=30), according to the WHO classification criteria. No statistically significant differences were found in other baseline characteristics between the three groups. The proportion of rapid responding patients was significantly lower in overweight patients (68%) and obese patients (64%), compared to patients in the normal BMI category (84%). BMI was an independent predictor of failure to respond, with odds ratios (OR) of 2.9 (95% CI 1.1;8.0) for the overweight group and 3.6 (95% CI 1.0;12.6) in the obese group. (table 1) Other independent predictors of failure to respond were female gender (OR 3.4 (95% C.I. 1.05;11.3)) and high baseline DAS (OR 2.1 (1.3;3.6)).

Table 1. BMI and failure to respond to IFX

BMI category*nCrude Odds ratio 95%C.I.Adjusted# Odds ratio 95% C.I.
<2552refref
25–<30662.6 (1.0; 6.4)2.9 (1.1; 8.0)
>=30253.1 (1.0; 9.4)3.6 (1.0; 12.6)
*BMI according to WHO classification of adult normal weight, overweight and obesity.#Adjusted for age, sex, smoking, baseline DAS and anti-citrullinated protein antibody (ACPA)-status.

Conclusion:

These results confirm that BMI is associated with response to IFX, with overweight and obese patients more often failing to treatment with IFX than patients with normal BMI, even when IFX is increased to the maximum dose (10mg/kg).

1.Klaasen, R et al. Body mass index and clinical response to infliximab in rheumatoid arthritis. Arthritis Rheum 2011 Feb;63(2):359–364.

To cite this abstract, please use the following information:
Heimans, L., van den Broek, M., Dirven, L., Schouffoer, A.A., Speyer, I., Kerstens, P.J.S.M., et al; Body Mass Index Is Associated with Decreased Response to Initial and Delayed Treatment with Dose Escalated Infliximab in Patients with Recent Onset Rheumatoid Arthritis. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :416
DOI:

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