Epidemiology of thrombotic risk factors: The difficulty in using clinical trials to develop a risk assessment model

Abstract

There is a paucity of data assessing the risks and prevention of venous thromboembolism in critical care settings. Consequently, it is difficult to estimate the risk of venous thromboembolism for a typical patient, on an individual basis, and this difficulty leads to underuse of thromboprophylaxis, especially in intensive care unit patients. Thrombosis is a multifactorial disease and patients may present multiple risk factors simultaneously. The problem in quantifying risk factors is to combine these risk factors even when they are not detected in the same multivariate analysis. A model for predicting the risk of venous thromboembolism in hospitalized medical patients has yet to be developed and validated. Meanwhile, other approaches have been proposed to replace the ideal study utilizing a large prospective cohort of hospitalized medical patients. In this context, several scoring systems based on risk assessment models have been proposed, some including the use of computerized electronic prompts, to help physicians prescribe appropriate prophylaxis. This article reviews evidence on the risk of venous thromboembolism associated with different medical conditions and risk factors, and presents a tentative risk-assessment model for risk stratification in hospitalized medical patients.

Disease burden and unmet needs for prevention of venous thromboembolism in medically ill patients in Europe show underutilisation of preventive therapies

“…Risk assessment models have been developed to facilitate clinical decision-making (2,53). Electronic alert programs based on programmed risk models have been implemented, resulting in improved prophylaxis use to a certain extent (6,(54)(55)(56). One study showed that physician alert reduced VTE incidence from 4.13 to 2.23 events per 1,000 patients (odds ratio [OR] 0.54; 95% confidence interval [CI] 0.20-1.33) (30).…”

“…immobilisation, acute medical illness, trauma, surgery, and certain therapies) risk factors (2). Medical illnesses that independently increase VTE risk include congestive heart failure (CHF), cancer, ischaemic stroke, renal and respiratory failure, hypertension, diabetes, chronic pulmonary disease, severe infection, and in-flammatory diseases (3)(4)(5)(6). Patients hospitalised for an acute medical illness carry multiple VTE risk factors, which have been reported to result in an eight-fold increase in VTE risk compared to the general population (3).…”

Incidence and risk factors for fatal pulmonary embolism after major trauma: a nested cohort study

“…heart failure). 25 Trauma patients with co-morbidities and an increased BMI may benefit most from early initiation of LMWH or placement of an IVC filter if they have contraindications to LMWH.…”

Venous thromboembolism in medical outpatients – a cross-sectional survey of risk assessment and prophylaxis

“…Risk assessment is crucial to provide the appropriate prophylaxis to the right patients (17). The current American College of Chest Physicians (ACCP) proposes three risk categories (13): 1) low risk for medical patients who are fully mobile and for whom the estimated risk of asymptomatic DVT without thromboprophylaxis is <10%; 2) moderate risk for medical patients, those for whom bed rest is prescribed, sick patients, or patients with a moderate risk for VTE plus high risk for bleeding, corresponding to a risk of DVT without thromboprophylaxis between 10% and 40%; and 3) high risk for VTE plus a high risk for bleeding, corresponding to a risk of DVT in the absence of thromboprophylaxis ≥40%.…”