Background Temporary lower limb immobilisation following injury is a risk factor for symptomatic venous thromboembolism (VTE). Pharmacological thromboprophylaxis can mitigate this risk but it is unclear which patients benefit from this intervention. The Aberdeen VTE risk tool was developed to tailor thromboprophylaxis decisions in these patients and this evaluation aimed to describe its performance in clinical practice. Secondarily, diagnostic metrics were compared with other risk assessment methods (RAMs).
Methods A prospective cohort service evaluation was conducted. Adult patients (≥16 years) managed with lower limb immobilisation for injury who were evaluated with the Aberdeen VTE risk tool prior to discharge from the ED were identified contemporaneously between February 2014 and December 2020. Electronic patient records were scrutinised up to 3 months after removal of immobilisation for the development of symptomatic VTE or sudden death due to pulmonary embolism (PE). Other RAMs, including the Thrombosis Risk Prediction for Patients with cast immobilisation (TRiP(cast)) and Plymouth scores, were assimilated retrospectively and diagnostic performance compared.
Results Of 1763 patients (mean age 46 (SD 18) years, 51% women), 15 (0.85%, 95% CI 0.52% to 1.40%) suffered a symptomatic VTE or death due to PE. The Aberdeen VTE tool identified 1053 (59.7%) patients for thromboprophylaxis with a sensitivity of 80.0% (95% CI 54.8% to 93.0%) and specificity of 40.4% (95% CI 38.1% to 42.6%) for the primary outcome. In 1695 patients, fewer were identified as high risk by the TRiP(cast) (33.3%) and Plymouth (24.4%) scores, but with greater specificity, 67.0% and 75.6%, respectively, than dichotomous RAMs, including the Aberdeen VTE tool.
Conclusion Routine use of the Aberdeen VTE tool in our population resulted in an incidence of symptomatic VTE of less than 1%. Ordinal RAMs, such as the TRiP(cast) score, may more accurately reflect VTE risk and permit more individually tailored thromboprophylaxis decisions but prospective comparison is needed.
- thrombo-embolic disease
- risk management
Data availability statement
All data relevant to the study are included in the article or uploaded as supplementary information.
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Handling editor David Metcalfe
Presented at Preliminary results of the performance of the Aberdeen VTE tool were presented at the Royal College of Emergency Medicine (RCEM) Scottish Clinical Meeting on 11 May 2016 in Glasgow, UK and at the RCEM Annual Scientific Conference on 20–22 September 2016 in Bournemouth, UK. Further results were presented virtually at the RCEM Medicine Scottish Clinical Meeting on 11 May 2021 and final results at the RCEM Scottish Clinical and Research Conference on 5 May 2022 in Edinburgh, UK.
Contributors HGW and JGC developed the Aberdeen VTE risk tool and conceived the service intervention and its design. SAA, AO-A, JH, BC, HE, AH, CE, PHT and JGC acquired the data. SAA, AO-A and JGC performed the analysis. SAA and JGC interpreted the data and drafted the manuscript. All authors reviewed the manuscript critically for important intellectual content and provided their final approval of the version to be submitted. All authors are accountable for the work and JGC is the guarantor of the study.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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