Risk Factors and Risk Assessment

The importance of hospitalisation and prevention of hospital acquired thrombosis (HAT)

The HSE sponsored Safermeds programme has identified that at least 60% of blood clots happen during or after a hospital stay and that up to 70% of these may be preventable.

Venous thromboembolism (VTE) refers to a blood clot or thrombus occurring in the deep veins, usually of a leg (deep vein thrombosis, DVT) and/or which has fragmented and travelled to the lungs (pulmonary embolism, PE). Approximately 11,000 Irish people may be affected by VTE every year and 9% of all deaths are VTE-related.

Recurrence affects approximately 30% of survivors and post-thrombotic complications are common. 63% of all VTE is hospital-acquired, occurring during or in the 90 days after hospitalisation. 70% of hospital-acquired VTE is potentially preventable with appropriate VTE prophylaxis.

Venous thromboembolism (VTE), encompassing DVT and PE, is a common disease, with an average annual incidence rate of about one case per 1000 [2]. A large, population-based study has shown that about half of all VTE episodes are provoked by hospitalisation for either surgery or a medical illness [2]. Of note, hospitalisation for either surgery or a medical illness accounted for similar proportions, emphasising the need to consider the risk of VTE in all hospitalised patients.

In this population study, other recognised risk factors accounted for 25% of all cases of VTE, and the remaining 25% of cases were not explained by accepted VTE risk factors and were regarded as idiopathic. This study pointed to the importance of identifying risk factors for VTE, in particular in people currently or recently hospitalised [2].

An individual’s risk profile determines the need for VTE prophylaxis

A person’s risk of VTE is determined on a case-by-case basis, taking into account the existing relevant risk factors of VTE and the chance that thromboprophylaxis may cause a side effect such as bleeding. Therefore, where relevant risk factors are present, an individually adjusted and risk-adapted thromboembolism prophylaxis is generally recommended [26].

In the case of surgically and medically ill patients, the individual overall risk of VTE is identified on the basis of patient-related factors (e.g. cancer) and admission-related factors (e.g. surgery). The type and duration of prophylaxis is then determined on the basis of the risk stratification [26].