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

BACKGROUND

Patients requiring lower limb immobilization after injury have an increased venous thromboembolism (VTE) risk. The extent of this risk in published studies varies. The Thrombosis Risk Prediction for Patients with Cast Immobilization (TRiP[cast]) model quantifies VTE risk using clinical parameters. Delineating low-risk from high-risk patients remains challenging.

OBJECTIVES

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

METHODS

TILLIRI is a multicenter, pragmatic, observational cohort study including 10 sites within the Irish Network for VTE Research. Patients aged ≥18 years with an immobilized 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%). Forty-three patients (3.5%) were lost to follow-up. Forty-four (3.6%) patients and 125 (10%) patients were prescribed anticoagulation and aspirin, respectively. Twenty-one patients receiving regular anticoagulation were removed from the final analysis. VTE incidence at 90-day follow-up was 6/1179 (0.51%; 95% CI, 0.1%-0.92%). TRiP(cast) scores were calculated for 1176/1221 patients. A total of 846 patients (71.9%) had a 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.