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.

Safety of Arthrocentesis in Patients on Chronic Warfarin Therapy with Therapeutic INR.

Ahmed2,  Imdad, Gertner1,  Elie

Regions Hospital, St Paul, MN
Regions Hospital


Patients often need arthrocentesis for diagnostic and therapeutic reasons while on chronic warfarin therapy. Often the procedure is delayed or avoided because of concern about bleeding. The aim of this retrospective study was to determine the safety of arthrocentesis in patients on chronic oral warfarin therapy with INR>=2.0.


From 01/ 2001 to 11/2008, we reviewed records at Regions Hospital and HealthPartners Medical Group of 514 consecutive patients on chronic warfarin therapy who underwent 640 joint aspiration procedures. Total of 456 procedures were performed with INR >=2.0 (Group A) and 184 procedures were performed with INR <2.0 (Group B).

The end points were: (1) clinically significant bleeding,(2) infection of the joint (3) pain in the joint needing emergency room, urgent care or physician visits. The end points were both early (within 24 hours post-procedure) and late (within 30-days). Indications for arthrocentesis were usually pain/effusion in patients with diseases such as rheumatoid arthritis, osteoarthritis, gout etc.


There were no significant differences in age, sex, body mass index and concurrent use of antiplatelet agents between the two groups. Groups were also comparable among all medical co-morbidites examined (diabetes mellitus, hypercoagulability, hypertension, liver failure, renal failure and smoking status). Mean INR at the time of procedure for group A was higher than group B (2.7±0.03 vs.1.6±0.02). [Table 1] shows the early and late complications in both groups.

Table 1. Early and late complications between two groups

ComplicationsGroup A INR > 2.0 N = 456Group B INR < 2.0 N = 184P Value
Clinically significant bleeding (early)1 (0.2%)0NS
Clinically significant bleeding (late)00NS
Infection (early)1 (0.2%)0NS
Infection (late)1 (0.2%)0NS
Pain causing physician visit3 (0.7%)0NS
NS = non significant.

There was no statistically significant difference in the overall complication rate between patients with INR >=2.0 (Group A) and patients with INR<2.0 (Group B) (p=0.708). Receiver operating characteristic [Figure-2] analysis showed that INR offered modest value as a predictive instrument, with a c-statistic of 0.615.

Figure 1. Receiver operating characteristic (ROC) analysis.


Arthrocentesis in patients on chronic warfarin therapy with therapeutic INR appears to be safe without an increased risk of bleeding complications. This approach simplifies the peri-procedural management of anticoagulation, and could lead to improved outcomes and reduced health care costs.

To cite this abstract, please use the following information:
Ahmed, Imdad, Gertner, Elie; Safety of Arthrocentesis in Patients on Chronic Warfarin Therapy with Therapeutic INR. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :910
DOI: 10.1002/art.28678

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