A new risk-prediction model designed for primary-care use can help identify asymptomatic patients at high risk of venous thromboembolism (VTE).

The QThrombosis Web Calculator employs algorithms based on simple clinical variables. Users are asked to provide the patient’s age, gender, height and weight; such clinical information as smoking status, presence of varicose veins and presence of such conditions as cancer, heart failure or chronic kidney disease; and information on current medication use. The tool then calculates VTE risk for one to five years.

The developers validated the risk-prediction algorithm in 564 general practices in England and Wales, studying data from more than 3.5 million patients aged 25 to 84 years. First-time cases of VTE — either deep-venous thrombosis (DVT) or pulmonary embolism (PE) — were identified from a patient’s medical records or death certificate (Hippisley-Cox J, Coupland C. BMJ. 2011;343:d4656).

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The QThrombosis risk calculator is not suitable for persons with a history of venous thrombosis, with symptoms suggestive of venous thrombosis or with a family history of thrombosis; for pregnant women; or for persons taking anticoagulants.

In another other large VTE research project, Suzanne C. Cannegieter, MD, PhD, and colleagues found that people with a history of clinical superficial venous thrombosis had a 6.3-fold increased risk of DVT and a 3.9-fold risk of PE (van Langevelde K et al. Blood. 2011;118: 4239-4241 ).