Hospital Deep Vein Thrombosis Detection Study in Cancer Patients Receiving Palliative Care (HIDDEN 2)

Patients with cancer are at a high risk of developing potentially dangerous blood clots (venous thromboembolism or VTE) due to the release of molecules which make the blood stickier. The risk of developing VTE is further increased by surgery, sudden medical illness and anticancer treatments such as chemotherapy, hormone therapy and immunotherapy.

Most VTEs start as blood clots in the legs known as Deep Vein Thromboses (DVT) which may have no symptoms but classically present as swollen legs. Untreated, these DVTs can break off and lodge in the lungs forming Pulmonary Emboli (PEs), causing a breadth of symptoms including cough, shortness of breath, chest pain, collapse and sometimes death.

Emergency hospital admission increases the risk of developing VTE by 20% regardless of whether a patient has cancer or not. Consequently, VTE prevention amongst hospitalised patients is an NHS health policy priority in England and Wales and has been shown to reduce avoidable harm and death.

Cancer patients are seven times more likely to develop VTE than the general population and the risk is further increased in advanced cancer and by treatment of cancer with chemotherapy or immunotherapy.

The studies upon which clinical guidelines for preventing VTE (thromboprophylaxis) are based, are over 20 years old and included less than 15% cancer patients. Also, studies excluded patients who were likely to have a poor outcome and who had a poor Performance Status (PS). It is therefore unclear whether we should apply these guidelines to patients with advanced cancer who are receiving palliative care.

We recently published the Hospice Deep Vein Thrombosis Detection study (HIDDen) which looked at how many hospice patients were effected by VTE and how useful thromboprophylaxis would be for these patients.

Leaving out 35% of patients who were admitted for end of life care, 28% of the remaining patients demonstrated large volume DVT. These caused few symptoms and there was no survival difference between those with or without DVT. Patients had high care needs and an average survival of 44 days.

A Lancet Haematology Editorial concluded that thromboprophylaxis was of limited utility in hospice patients of poor PS and prognosis. These data have already changed the way we treat these patients. The UK hospice/Specialist Palliative Care Unit (SPCU) population, represents a fraction of palliative care inpatients - the majority (up to 80,000 per year) are admitted to hospital. Other data suggests the acutely admitted palliative patient is of better PS and prognosis and the data from HIDDen may not be applicable in the hospital setting.

As a natural progression of HIDDen, we believe it is important that the study is repeated in the hospital setting, in a larger earlier-stage, better prognosis population. We propose a study in advanced cancer patients to find out:

- How common DVT is in these patients when they come into hospital.

- What symptoms these patients have.

- The 90-day incidence of hospital acquired thrombosis.

- If there is an association between DVT and survival.

We plan to recruit 232 patients from four acute hospitals across South East Wales over 10 months, so that we may answer these important questions. By not undertaking this research we risk continuing to treat some of our most vulnerable poorly cancer patients according guidelines derived from out of date studies from an unrepresentative population.