A prospective observational study of a cohort of outpatients with an acute medical event and reduced mobility: incidence of symptomatic thromboembolism and description of thromboprophylaxis practices

Abstract

The study was performed to determine the incidence of symptomatic venous thromboembolism in outpatients with an acute medical event causing temporary reduced mobility. Risk factors for venous thromboembolism and thromboprophylaxis practices were also studied. This was a prospective, observational, multicentre, cohort study. General practitioners randomly selected from a registry of 25,000 active representative doctors in France including eligible outpatients. Outpatients aged at least 40 years anticipated to have reduced mobility for at least 48 h due to an acute medical event were eligible. None required. Symptomatic deep-vein thrombosis and pulmonary embolism at 3 weeks were the main study end-points. Overall, 16,532 evaluable patients of mean age 71 years were recruited between October 2002 and June 2003 by 2895 doctors. The main acute medical events leading to reduced mobility were infection, acute rheumatism and falls without fracture. The incidence rates (95% confidence interval) of symptomatic deep-vein thrombosis and pulmonary embolism were 1% (0.84-1.14) and 0.20% (0.13-0.27) respectively. Venous insufficiency in legs, cancer, and a personal or family history of venous thromboembolism were independent risk factors for venous thromboembolism. Pharmacological thromboprophylaxis was initiated in 35.0% (n=5782) of the patients. The principal driver of prescription was a personal history of venous thromboembolism. The risk of symptomatic venous thromboembolism in outpatients with reduced mobility for medical reasons is close to that reported in medical and surgical inpatients. This risk and the potential need for thromboprophylaxis should be taken into account by primary care doctors.