Received March 27, 2008
Accepted on July 24, 2008

ORIGINAL ARTICLES

D-Dimer Level and the Risk for Thrombosis in Systemic Lupus Erythematosus

Haifeng Wu ^*, Daniel J. Birmingham , Brad Rovin , Kevin V. Hackshaw , Nabil Haddad , Douglas Haden , Chack-Yung Yu , and Lee A. Hebert ¹

Departments of *Pathology, Internal Medicine, and Pediatrics, Ohio State University Medical Center, Columbus, Ohio

¹ To whom correspondence should be addressed. E-mail: lee.hebert{at}osumc.edu.

	Abstract

Background and objectives: Patients who have systemic lupus erythematosus (SLE) and manifest antiphospholipid antibodies (APA) are at increased risk for thrombosis; however, it is difficult to predict who will clot. This study tested the hypothesis that peak D-dimer level measured routinely during follow-up identifies whether a hypercoagulable state is developing and, therefore, the patient is at increased risk for thrombosis.

Design, setting, participants, & measurements: One hundred consecutive patients who had SLE with recurrent activity (71% renal SLE) and were evaluated for or enrolled in the Ohio SLE Study were studied. D-dimer testing was done annually and usually at SLE flare or other serious illness. When D-dimer was elevated, evaluation for thrombosis (large vessel, small vessel, or Libman-Sacks) was undertaken. Mean follow-up was 37.5 ± 15 SD months.

Results: Of those with peak D-dimer <0.5 µg/ml (n = 46), 0% thrombosed, 33% had APA. Of those with peak D-dimer 0.5 to 2.0 µg/ml (n = 19), 6% thrombosed, 44% had APA. Of those with peak D-dimer >2.0 µg/ml (n = 36), 42% thrombosed, 76% had APA. The most common causes of elevated D-dimer in the absence of demonstrable thrombosis were SLE flare and systemic infection. D-dimer levels were usually elevated for several months before thrombosis.

Conclusions: Patients with SLE and normal D-dimer levels are at low risk for thrombosis, irrespective of APA status. Those with persistent unexplained elevated D-dimer levels, particularly when >2.0 µg/ml, are at high risk for thrombosis.