The (T) thrombosis (I) in patients with (L) lower (L) limb (I) injuries (R) requiring (I) immobilisation (TILLIRI) Study.

Abstract

Background: Patients requiring lower limb immobilisation after injury have an increased venous thromboembolism (VTE) risk. The extent of this risk in published studies varies. The TRiP(cast) model quantifies VTE risk using clinical parameters. Delineating low from high-risk patients remains challenging.

Aims: Determine the 90-day incidence of symptomatic VTE following temporary lower limb immobilisation after injury in an unselected cohort. Prospectively collect data on risk factors, including those incorporated in TRiP(cast) model, to calculate TRiP(cast) scores.

Methods: TILLIRI is a multi-centre, pragmatic observational cohort study including 10 sites within the Irish Network for VTE Research. Patients≥18 years with an immobilised injured lower limb were included. Twenty-one clinical variables were collected at presentation. Thromboprophylaxis was prescribed according to clinical gestalt. Patients were followed up at 90-days to determine if VTE occurred.

Results: Between November 2018 and February 2023, 1242 patients were recruited. Follow-up was complete for 1199 patients(96.5%).43 patients(3.5%) were lost to follow-up.44(3.6%) patients and 125(10%) patients were prescribed anticoagulation and aspirin respectively. 21 patients receiving regular anticoagulation removed from final analysis. VTE incidence at 90-day follow-up was 6/1179(0.51%; CI 0.1%-0.92%). TRiP(cast) scores were calculated for 1176/1221 patients. 846 patients(71.9%) had TRiP(cast) Score< 7, received no prophylaxis and had no VTE.

Conclusion: TILLIRI indicates a low VTE incidence in an unselected cohort following lower limb immobilization with low rates of prophylaxis use. The proportion of patients with low TRiP(cast) scores and no symptomatic VTE suggests that thromboprophylaxis may be avoided in patients with TRiP(cast)scores< 7, with a low 90-day VTE risk.