Clinical manifestations and outcomes of antithrombotic treatment of the Tan Tock Seng Hospital Singapore antiphospholipid syndrome cohort.

To examine the clinical manifestations, intensity of oral anticoagulation and outcomes in the prevention of recurrent thromboses in patients with antiphospholipid syndrome (APS) in a tertiary rheumatology centre in Singapore. Retrospective case review of consecutive patients with APS attending a rheumatology clinic from 1st January 2004 to 31st December 2005. There were 59 (44%) patients with definite APS and 75 (56%) with probable APS. Systemic lupus erythematosus (SLE) was the most common cause of secondary APS. Hypertension and hyperlipidaemia were the most common cardiovascular comorbidities. The most common manifestations were haematological (thrombocytopaenia and haemolytic anaemia), neurological (seizure, headache) and pulmonary hypertension. Among those with definite APS, there were similar proportions with arterial and venous thromboses. Recurrent thromboses occurred in 14 (23.7%) patient with definite APS receiving warfarin, comprising 14 (73.7%) episodes of arterial and 5 (26.3%) episodes of venous thromboses. Recurrent arterial thromboses occurred at international normalized ratio (INR) of <2 in 5 (35.7%), INR 2-3 in 6 (42.9%), INR > 3 in 3 (21.4%) episodes, respectively. Recurrent venous thromboses occurred at INR < 2 in 4 (80.0%) and INR > 3 in 1 (20.0%) episode, respectively. Twenty-eight episodes of bleeding occurred in 21 (35.6%) patients, the majority (78.6%) being minor bleeding. Two-thirds of all major bleeds occurred at INR >/= 3. Venous and arterial thromboses were equally common in our patients with definite APS, although recurrent thromboses were more common in the arterial circulation. Target INR > 3 was associated with lower rates of recurrent arterial thromboses but higher rates of major and recurrent bleeding. Target INR >/= 2 appeared to be sufficient to prevent recurrent venous thromboses.