Targeted prophylactic anticoagulation based on the TRiP(cast) score in patients with lower limb immobilisation: a multicentre, stepped wedge, randomised implementation trial
Study (n=1505) suggests large proportion of this population could safely avoid thromboprophylaxis based on finding that those with TRiP(cast) score <7 (77% of study) who were not on anticoagulation had a very low risk of symptomatic VTE (3-month rate 0.7%; 95% CI 0.3–1.4).
Source:
The Lancet
SPS commentary:
The Thrombosis Risk Prediction for Patients with Cast Immobilisation—TRiP(cast)—score aims to predict the absolute risk of venous thromboembolism within 3 months after lower limb trauma requiring immobilisation. It was designed to help physicians to decide whether to prescribe a prophylactic anticoagulant and has been retrospectively validated in both a trial population (POT-CAST trial) and a cohort study. The purpose of this study was to determine the safety of withholding pharmacological prophylaxis for patients with lower limb trauma and immobilisation who are deemed at low risk of VTE (TRiP(cast) score < 7).
During the control phase, participating centres prescribed anticoagulation (mainly enoxaparin 40mg once daily or fondaparinux 2.5mg once daily) according to local practice, with physicians completely autonomous in their decision to prescribe or not to prescribe. During the intervention phase the TRiP(cast) score was used to target prophylactic anticoagulation to those with a score of 7 or higher.
There was a large reduction in prescribing between phases (absolute difference of 26%) and despite this, there was no difference between phases in terms of the cumulative rate of symptomatic VTE (control risk 1.0%, absolute difference 0.1% [95% CI –0.8 to 1.1]).
An accompanying comment notes the TRiP(cast) tool has now been fully validated, and “delivers the optimal trade-off between sensitivity and specificity that has been previously identified to be effective (sensitivity 85.7%, specificity 32.2%, negative predictive value 99.3%)”. The authors say that “as a direct consequence of this study, patients at low risk of venous thromboembolism can safely avoid ineffective and potentially harmful anticoagulation.” A new study (NIHR154716), funded by the National Institute for Health and Care Research, will help to determine the most effective and safe anticoagulant for individuals stratified by baseline risk using this tool.