Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Are Venous Thrombotic Events (VTE) Increased in Patients with Rheumatoid Arthritis (RA) Treated with Anti-TNF Therapy? Results from the British Society for Rheumatology Biologics Register (BSRBR).

Davies,  Rebecca, Galloway,  James, Watson,  Kath D., Lunt,  Mark, BSRBR Control Centre Consortium,  , Symmons,  Deborah P. M., Hyrich,  Kimme L.

Background:

Case reports have shown that TNF decreases platelet activation and inhibits thrombus formation, and so blocking TNF may contribute to thrombus formation. Research looking at the role of such therapies on venous thrombotic events (VTE) in RA patients has produced conflicting results with more recent studies documenting an increased risk, particularly in post-orthopaedic surgery patients. The aims of this analysis were (1) to compare rates of VTE in RA patients treated with anti-TNF vs. non-biologic disease modifying anti-rheumatic drugs (nbDMARDs) alone and (2) to compare the rates between each individual anti-TNF and nbDMARDs.

Methods:

To 31/10/2009, 11,881 anti-TNF and 3,673 biologic-naive nbDMARD control patients had been recruited to the BSRBR, a UK national register of active RA patients on biologic therapy. All patients were followed by regular hospital and patient questionnaires. This on-drug analysis, limited to first biologic only, followed all patients until first VTE (defined as deep venous thrombosis or pulmonary embolism), death, treatment discontinuation or last follow-up date, whichever came first. Cox proportional hazards models were used to compare rates of VTE between cohorts. Inverse probability of treatment weighting (IPTW) was used to adjust for the confounding effect of baseline differences between groups, including age, gender, diabetes, steroid use, smoking, BMI, hypertension, disease duration, severity and year of entry into the study. Surgery was entered into the model as a time-varying covariate, with patients viewed as being at increased risk for 90 days post-procedure. Missing baseline data were accounted for using multiple imputation.

Results:

The anti-TNF cohort was younger (mean 56 v 60 years), had a higher proportion of females (76 v 72%) and more severe disease (mean DAS28/HAQ: anti-TNF 6.6/2.0, nbDMARD 5.1/1.5). The median duration of follow up was 4.3 years (IQR 2.9, 5.4) in the anti-TNF cohort, and 3.0 years (IQR 1.7, 4.2) in the nbDMARD cohort.

A total of 204 first VTE's were reported (160 anti-TNF, 44 nbDMARD). 13% of anti-TNF and 7% of nbDMARD VTE events were reported within 90 days of hip or knee replacement. Overall there was no difference in the rate of VTE between anti-TNF and nbDMARD treated patients (adjusted HR 0.9 (95% CI 0.5, 1.6). The risk was similar across all anti-TNF agents.

Conclusion:

Anti-TNF therapy is not associated with an increased risk of VTE in RA patients. There is also no difference in VTE risk between the anti-TNF drugs.

Table: Patient characteristics and incidence of VTEs.

 nbDMARDAll anti-TNFETN**INF**ADA**
Subjects (n)367311881413934754267
Exposure (pyrs)11418328111364895499614
Surgeries, n12104370192212431205
Hip/knee replacement, n54525641129750685
All VTE events: n44160556738
VTE within 90 days of surgery, n (%)5 (12)34 (21)10 (19)17 (24)7 (18)
VTE within 90 days hip/knee replacement, n (%)3 (7)20 (13)6 (11)9 (13)5 (13)
VTE incident rate/1000 pyrs3.9 [2.8, 5.2]4.9 [4.2, 5.7]4.0 [3.0, 5.2]7.0 [5.4, 8.9]4.0 [2.8, 5.4]
VTE adjusted HR*Ref0.9 [0.5, 1.6]0.6 [0.3, 1.2]1.1 [0.6, 2.1]0.9 [0.4, 1.8]
*Adjusting for potential confounders was performed using an inverse probability of treatment weighted propensity model.
Including age, gender, diabetes, baseline steroid exposure, smoking, BMI, hypertension, surgery, disease duration, disease severity and year of entry into study.
**ETN = Etanercept, INF = Infliximab, ADA = Adalimumab

To cite this abstract, please use the following information:
Davies, Rebecca, Galloway, James, Watson, Kath D., Lunt, Mark, BSRBR Control Centre Consortium, , Symmons, Deborah P. M., et al; Are Venous Thrombotic Events (VTE) Increased in Patients with Rheumatoid Arthritis (RA) Treated with Anti-TNF Therapy? Results from the British Society for Rheumatology Biologics Register (BSRBR). [abstract]. Arthritis Rheum 2010;62 Suppl 10 :374
DOI: 10.1002/art.28143

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