OC 54.5 - Incidence and predictors of venous thromboembolisms in ambulatory patients: a retrospective analysis of 43 906 same-day-emergency-care attendances using electronic health records

Background: Same-day emergency care (SDEC) is an expanding area of acute medicine. It aims to minimise and remove delays in the patient pathway, allowing services to process medical emergency patients within the same day as an alternative to hospital admission. Venous thromboembolism (VTE) prevention is a key medical inpatient safety measure. It is unknown whether or not VTE prevention should be considered for SDEC patients.

Aims: To examine the incidence and key predictors associated with VTE diagnosed within 90 days of SDEC.

Methods: Data were obtained from coding of Electronic Health Records of people who received SDEC at Oxford University Hospitals between April 2016 and March 2021. Any repeat SDEC attendances within 30 days of initial attendance were grouped as a single episode. A multivariable logistic regression examined the association of 13 predictors and the occurrence of a VTE.

Results: There were 43906 attendance episodes, by 36922 individuals. Median age was 61 years (IQR 42.0; 77.0), and 55.1% were women (table 1). 407 patients (0.9 %) developed a VTE within 90 days of SDEC. Age more than 60 years, prior malignancy (OR 4.03, p<0.0001) and prior diseases of the circulatory system (OR 2.78, p <0.0001) were predictors for VTE (table 2). VTE was not associated with whether or not a VTE risk assessment had been completed, but having one or more additional SDEC attendance within a 30 day ‘attendance episode’ was associated with increased VTE risk (OR 4.22, p<0.0001). 42.0 % of patients had at least 1 separate inpatient admission, in addition to SDEC attendance, within 90 days of the VTE.

Conclusion(s): The incidence of VTE following SDEC was low. Routine thromboprophylaxis in SDEC would be unlikely to be justified unless higher risk groups can be robustly identified.