Screening for asymptomatic thrombophilia reduces provoked VTE risk

8 March 2010

MedWire News: Screening asymptomatic relatives of patients with hereditary thrombophilias identifies individuals who may benefit from thromboprophylaxis, Dutch researchers have found.

Through screening, relatives may reduce their risk for provoked episodes of venous thromboembolism (VTE) by using anticoagulants, explain Bakhtawar Khan Mahmoodi (University Medical Center Groningen) and co-authors.

However, the risk for idiopathic episodes of VTE is unaffected by screening, the team notes in the Journal of Thrombosis and Haemostasis.

The researchers followed-up 382 relatives of 84 VTE patients with a deficiency in Protein C, Protein S, or antithrombin. The relatives were examined for thrombophilias and exogenous risk factors including surgery, immobilization, hormone therapy, malignancy, and pregnancy.

Overall, 39% of relatives were found to have a hereditary thrombophilia.

Relatives with and without thrombophilias were followed-up for an average of 9.2 and 9.0 years, respectively. During this time, the annual incidence of VTE in the thrombophilic and non-thrombophilic relatives was 1.53% and 0.29%, respectively, giving a significant hazard ratio of 7.0.

The incidence of unprovoked VTE significantly differed between relatives with and without thrombophilia, at 0.95% versus 0.05%, but no significant difference was detected in the rates of provoked VTE, at 0.58% versus 0.24%.

Of note, 37% of thrombophilic and 34% of non-thrombophilic relatives had 91 and 143 exogenous risk factors for VTE during the study, respectively, and VTE occurred in 6.6% and 3.5% of the groups, respectively. This was despite the greater use of thromboprophylaxis in thrombophilic than non-thrombophilic patients, the researchers note (51% vs 22%).

Furthermore, all six episodes of provoked VTE in thrombophilic relatives occurred when no thromboprophylaxis was used.

“We confirmed the high absolute risk of VTE in subjects with hereditary protein S, protein C or antithrombin deficiencies in a large well-defined prospective cohort with long follow-up,” Mahmoodi et al conclude.

“For the prevention of unprovoked VTE, the value of testing is obviously limited.However, most cases of provoked VTE will be avoidable if appropriate thromboprophylaxis is applied, underlining the value of screening.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

J Thromb Haemost 2010; Advance online publication