D-dimer levels in patients with thromboangiitis obliterans.

Background: Thromboangiitis obliterans (TAO) or Buerger disease is a recurring progressive segmental vasculopathy that presents with inflammation and thrombosis of small and medium arteries and veins of the hands and feet. The exact cause remains unknown, with tobacco use (primarily smoking but also smokeless tobacco) being highly associated with the disease. The diagnosis is clinical and the lack of a diagnostic gold standard is a deterrent to diagnosing it in patients with atypical presentations. Obliterative endarteritis occurs perhaps due to a mixture of thrombosis and inflammation. The diagnostic sensitivity and specificity of D-dimer as a biomarker for thrombosis is well reported from its use in other areas such as deep vein thrombosis. Identification of a biomarker linked to the causation yields a diagnostic adjunct with a role in therapeutic decision-making, aiding diagnosis in atypical presentation, monitoring disease activity and gauging response to therapy.

Methods: Between April 2014 and May 2015, we studied serum D-dimer (a marker of thrombosis) in 62 patients with TAO and compared this to 330 normal age- and sex-matched controls. We included all patients with peripheral arterial disease clinically diagnosed to have TAO according to the Shionoya criteria. There was no history of thrombosis or arterial disease in the control group. The control group was matched for baseline characteristics such as age and sex. All patients underwent a standard diagnostic protocol including blood tests (haemoglobin and creatinine), electrocardiogram, chest X-ray and ankle brachial pressure index. Blood was collected using an evacuated tube system into a citrate anticoagulant tube for testing D-dimer.

Results: All the 62 patients diagnosed to have TAO were men with an average age of 40 years (range 18-65 years). They all had a history of tobacco use and did not have other atherogenic risk factors (part of the diagnostic criteria). Medium-vessel involvement was present in 53 patients (85%) and the rest presented with additional involvement of the popliteal and femoral vessels. Upper limb involvement or superficial thrombophlebitis was present in 95% of patients. Laboratory and imaging studies were consistent with TAO. The groups were well matched for age (p = 0.3). The median and interquartile range for D-dimer values were 61 ng/ml and 41-88 ng/ml in controls (n = 330) and 247 ng/ml and 126478 ng/ml in patients (n = 62), respectively (p<0.001).

Conclusions: D-dimer levels are considerably elevated in patients with TAO. This indicates an underlying thrombotic process and suggests its potential role as a diagnostic adjunct. It also leads us to hypothesize a potential therapeutic benefit of anticoagulants in this disease.