Current Practice of Testing for Hereditary Thrombophilia in the Netherlands.

Inherited thrombophilia is known to increase the risk for venous thromboembolism (VTE). Furthermore, an association between recurrent pregnancy loss and hypertensive pregnancy complications (including preeclampsia and HELLP syndrome) appears present. A relationship between thrombophilia and arterial cardiovascular disease could not be demonstrated in most studies. Since thrombophilia is prevalent in patients with VTE, testing for these abnormalities often reveals positive test results which may lead to widespread testing. This is also the case in patients with various other conditions. However, there is little convincing evidence about effectiveness of testing due to the uncertainty with respect to therapeutic consequences of a positive thrombophilia test results.

To assess the current practice of thrombophilia testing in The Netherlands and to get an impression of the therapeutic implications of testing for patients, simple questionnaires were sent out to physicians that ordered tests for protein S, C, or antithrombin activity, factor V Leiden (or APC resistance) or the prothrombin 20210A mutation in 1998 consecutive individuals who were investigated between November 2003 and March 2004. The tests were performed in a laboratory that serves as a diagnostic facility for mainly non-academic hospitals and general practitioners throughout the Netherlands. Of a total of 1265 returned questionnaires, 1130 were suitable for analysis (response rate 63%). Of the tested individuals, 64% were female (median age 38 years, inter-quartile-range [IQR] 30–50) and 35% were male (median age 51, IQR 41–59). Tests were ordered by internists (37%), gynaecologists (20%), neurologists (15%) and general practitioners (13%). Only 42% of the tested individuals had experienced VTE, 23% arterial cardiovascular disease, and 17% had had pregnancy complications. A known carrier or VTE in the family was the reason for testing in 180 asymptomatic individuals (16%). Testing had had no therapeutic consequences in 869 tests (77%). In 32% of these patients, physicians stated that had the test revealed a thrombophilic defect, this would not have altered management of the patient.

This study shows that testing for thrombophilia occurs very often in patients with various conditions. In the majority of cases, the results do not change therapeutic management of tested patients. Widespread thrombophilia testing is costly and may cause unnecessary concern in carriers. This study underscores the need to acquire high level evidence about its effectiveness that should include clinical outcomes as well as quality of life and costs.