Quarterly audit on venous thromboembolism (VTE) prevention: Strengthening patient safety in hospitals

A recent quarterly audit at Chelsea and Westminster Hospital NHS Foundation Trust evaluated how effectively VTE prevention measures are being applied across inpatient settings.

Why VTE prevention in hospitals matters

VTE, which includes both deep vein thrombosis (DVT) and pulmonary embolism (PE), can be life-threatening but is often preventable when hospitals follow best practice. National standards require that all adult inpatients have a VTE risk assessment completed within 14 and 24 hours of admission, and that those identified as being at risk receive appropriate pharmacological and/or mechanical thromboprophylaxis unless contraindicated.

Pharmacists are central to VTE stewardship, supporting accurate risk assessments, ensuring timely prescribing, and advising on complex clinical decisions (e.g. heparin allergy management). This collaborative approach reduces adverse outcomes, improves care quality, and safeguards patients.

Aim of the audit

The quarterly audit set out to evaluate whether adult inpatients across two hospital sites were receiving appropriate VTE prevention measures and to assess compliance with both local and national standards. The targets included at least 95% completion of risk assessments within 14 and 24 hours of admission, at least 90% prescribing of pharmacological thromboprophylaxis where appropriate, and at least 90% prescribing of mechanical thromboprophylaxis where indicated.

How the audit was conducted

In March 2025, pharmacists carried out a retrospective audit involving 328 adult inpatients. Ten patients were randomly reviewed on each adult ward across the two hospital sites. Data were drawn from electronic prescribing and administration records, VTE risk assessment forms, admission documentation, and pathology results such as renal function. The audit captured whether patients had a completed risk assessment, whether they received pharmacological or mechanical thromboprophylaxis, and whether any omitted doses were documented with reasons. 

Results: Where hospitals are performing well, and where gaps remain

The audit showed areas of both strong performance and clear room for improvement. Risk assessments were completed within 14 hours for 81% of patients, rising to 96% by 24 hours. While the latter figure meets the national target, the 14-hour rate fell short of the 95% standard. Pharmacological thromboprophylaxis prescribing was a strength, with 99% of eligible patients receiving appropriate anticoagulant prophylaxis unless contraindicated. By contrast, mechanical thromboprophylaxis was less consistent: only 77% of eligible patients were provided with devices such as compression stockings, highlighting an important gap in care.

Key lessons and shared learning

These findings suggest that although pharmacological prescribing is strong, improvements are needed in both timely risk assessment and consistent use of mechanical prophylaxis. In response, the audit team introduced a quarterly VTE dashboard to share performance data and key learning points across the organisation. Shared learning focused on ensuring timely and accurate VTE risk assessment at admission to guide decision-making, as well as re-assessment in maternity inpatients following delivery to support postpartum thromboprophylaxis. The results also reinforced the importance of weight- and renal function–based dosing for anticoagulants, greater consistency in the use of mechanical thromboprophylaxis in surgical, maternity, and critical care patients (unless contraindicated), and thorough documentation when thromboprophylaxis is withheld or suspended. The team also emphasised the need to escalate cases where patients decline anticoagulation to ensure appropriate follow-up, and to review hospital-associated VTE events to identify contributory factors and prevent recurrence. 

Conclusion: Embedding VTE stewardship in everyday practice

The audit demonstrates that while progress has been made in prescribing pharmacological thromboprophylaxis, hospitals must strengthen both mechanical prophylaxis use and timely risk assessment to meet national standards consistently. Embedding VTE prevention into everyday practice requires a combination of ongoing staff education, clear documentation processes, multidisciplinary collaboration, and strong pharmacist leadership in stewardship. By reinforcing these measures, hospitals can reduce preventable harm, improve patient outcomes, and lessen the long-term burden of VTE on healthcare systems.

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About the authors

Sheena Patel and Clarissa Pui are Clinical Pharmacists at Chelsea and Westminster Hospital NHS Foundation Trust