The (T) thrombosis (I) in patients with (L) lower (L) limb (I) injuries (R) requiring (I) immobilisation (TILLIRI) study: A prospective observational multicentre study

T. O Halloran¹, M. Watts¹, S. Egan², M. O’Donoghue³, B. Bleach⁴, T. Breslin⁵, M. Alshafie⁵, J. O'Driscoll⁵, B. Nemeth⁶, S. Cannegieter⁷, S. O'Rourke⁸, M. Barlow⁸, N. Salter⁹, A. Wakai¹⁰, N. O'Connell¹¹, M. Nolan¹², M. Crowley¹³, A. Burke¹⁴, M. Maxwell¹⁵, D. O Keeffe¹

¹University Hospital Limerick, Limerick, Limerick, Ireland, ²University Hospital Limerick, University of Limerick, limerick, Limerick, Ireland, ³St Johns Hospital, University of Limerick Hospital Group, limerick, Limerick, Ireland, ⁴Ennis Hospital, University of Limerick Hospital Group, Ennis, Clare, Ireland, ⁵Mater Misericordiae University Hospital, Dublin, Dublin, Ireland, ⁶Department of Clinical Epidemiology and Department of Orthopedics, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands, ⁷Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands, ⁸Midland Regional Hospital Tullamore, Tullamore, Offaly, Ireland, ⁹St Vincents University Hospital, Dublin, Dublin, Ireland, ¹⁰Beaumont Hospital, Dublin, Dublin, Ireland, ¹¹St James's Hospital,Dublin8, Dublin, Dublin, Ireland, ¹²St James's Hospital, Dublin, Dublin, Ireland, ¹³Cork University Hospital, Cork, Cork, Ireland, ¹⁴Sligo University Hospital, Sligo, Sligo, Ireland, ¹⁵Sligo University Hospital, Dublin, Dublin, Ireland

Abstract Number: PB1334

Meeting: ISTH 2022 Congress

Theme: Venous Thromboembolism » VTE Epidemiology

Background: Patients requiring temporary lower limb immobilisation after an injury have an increased venous thromboembolism (VTE) risk. The magnitude of this reported risk varies between studies, likely due to heterogeneity in study design. Contextualizing risks within populations is therefore challenging. Moreover, contributing risk factors remain incompletely characterized.

Aims: We aim to determine the 90-day incidence of symptomatic VTE after temporary lower limb immobilisation and to externally validate the “Thrombosis Risk Prediction for patients with cast immobilisation (TRiP (cast))” risk assessment model (RAM), which was developed using data from the MEGA case-control study (Nemeth B (Cannegieter S) et al. DOI: 10.1016/j.eclinm.2020.100270).

Methods: TILLIRI is a prospective, multicentre observational study including 12 participating sites within the Irish Network for VTE Research (INViTE). Consecutive patients aged 18 years and older with an immobilised injured lower limb are eligible for inclusion. The primary outome is the incidence of symptomatic VTE at 90 days. We also aim to externally validate the TRiP (cast) RAM within the TILLIRI cohort using clinical variables collected at the index visit. In contrast to earlier studies, this is a highly unselected population. Our target sample size is 3900 patients.

Results: 912 patients have been included to date from 12 sites. Follow up is complete for 770. 691/770 90% did not have pharmacological thromboprophylaxis prescribed. In line with our study protocol, an interim analysis of 90-day VTE rate will be performed after 1000 patients have completed follow-up and all data recorded centrally. To date, the mean (SD) TRiP (cast) score is 5.4±2.4.

Conclusion(s): Predicted and actual recruitment are similar in this large prospective observational study within INViTE, demonstrating feasibility. The TILLIRI study is recruiting a highly unselected population, an important consideration for generalizability of outcomes. We anticipate that our planned interim analysis will be conducted in Q1 2022 and that recruitment will complete on target.

To cite this abstract in AMA style:

O Halloran T, Watts M, Egan S, O’Donoghue M, Bleach B, Breslin T, Alshafie M, O'Driscoll J, Nemeth B, Cannegieter S, O'Rourke S, Barlow M, Salter N, Wakai A, O'Connell N, Nolan M, Crowley M, Burke A, Maxwell M, O Keeffe D. The (T) thrombosis (I) in patients with (L) lower (L) limb (I) injuries (R) requiring (I) immobilisation (TILLIRI) study: A prospective observational multicentre study – Early Results [abstract]. https://abstracts.isth.org/abstract/the-t-thrombosis-i-in-patients-with-l-lower-l-limb-i-injuries-r-requiring-i-immobilisation-tilliri-study-a-prospective-observational-multicentre-study-early-results/. Accessed September 21, 2023.

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