A Three-year Retrospective Study Looking at Preventing Hospital Acquired Thrombosis

Hospital-acquired venous thromboembolism (HA-VTE) is defined as cases of venous thromboembolism (VTE) that occur in a hospital and within ninety days of a hospital admission. Deep vein thromboses (DVTs) most commonly occur within the deep veins of the pelvis and legs. If the thrombus dislodges and travels to the lungs, it can result in a pulmonary embolus (PE). VTE is associated with significant morbidity and mortality, accounting for almost 10% of all hospital deaths. If risk factors are correctly identified and VTE prophylaxis is prescribed, VTE can be a preventable condition. In 2010, NHS England launched The National Venous Thromboembolism Prevention Programme. This included NICE guidance, and a VTE risk assessment tool, which must be completed for at least 95% of patients on admission. The National Thrombosis Survey, published by Thrombosis UK, studied how this program was implemented locally, and audited HA-VTE prevention strategies nationally.

Using the Thrombosis Survey and NICE guidance as an aide, this study collects data about hospital-acquired DVT (HA-DVT) at the Queen Elizabeth Hospital in Gateshead (QEH) and aims to: 1. Identify cases of HA-DVT and understand the clinical circumstances surrounding these cases 2. Assess the quality of VTE preventative measures at QEH 3. Outline potential improvement in reducing the incidence of HA-VTE at this hospital Methods: This retrospective cohort study used electronic records to identify all cases of DVT between April 2019 and April 2022 at QEH. Cases of HA-DVT were defined as: a positive ultrasound doppler report and either the case occurring in the 90 days following an inpatient stay, or beyond two days into an admission. For these cases of HA-DVT, we recorded the: reason for admission; admitting specialty; presence of an underlying active cancer and deaths occurring within 90 days of diagnosis. We assessed the quality of VTE preventative measures, by recording the: completion of VTE risk assessments; prescription of weight-adjusted pharmacological VTE prophylaxis and provision of VTE prophylaxis on discharge. For HA-DVT cases occurring within 90 days of an inpatient stay, the preventative measures were assessed on the original admission. Electronic records were used to record the completion rate of the National VTE risk assessment tool for all inpatients during this time frame.

The VTE risk assessment tool was completed for 98.5% of all admissions. One hundred and thirty-five cases of HA-DVT were identified between April 2019 and April 2022. Sixteen patients with HA-DVT did not have VTE prophylaxis prescribed on admission. Eleven of these patients had a clearly documented reason why anticoagulation was avoided. In HA-DVT cases where pharmacological VTE prophylaxis was prescribed, 23% were prescribed an inappropriate dose for their weight. If anticoagulation was required on discharge, this was prescribed appropriately in 94% of cases. About 31% of the patients with HA-DVT had an underlying active malignancy. Thirty-nine patients died within 90 days of the DVT being diagnosed; in only 1 case was VTE thought to be a contributing factor to death.

The hospital exceeded the national standard of VTE risk assessment completion on admission (greater than 95%). For almost a quarter of patients with HA-DVT, the dose of thromboprophylaxis prescribed was not appropriate for weight. In five cases of HA-DVT, thromboprophylaxis was omitted with no clear justification. HA-DVT often affects the most clinically vulnerable patients and is associated with a high mortality.