The use of an oral anticoagulant medicine in medically ill patients for 45 days following their discharge from the hospital reduces the rate of non-fatal symptomatic blood clots with no impact on fatal blood clots.
Professor Alex Spyropoulos, the study author, of the Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, New York, US, said: "Anticoagulants help prevent blood clots in medically ill patients while they are under our supervision at the hospital. However, the risk of blood clots extends well beyond this period."
"Our results suggest we may be able to offer further protection to patients at risk from non-fatal blood clots, with no increase in major bleeding, by prescribing an oral anticoagulant for use after discharge. This study has the potential to reduce the public health care burden of non-fatal blood clots in a large proportion of medically ill patients," said Spyropoulos.
Each year, around 20 million acutely ill medical patients are hospitalized in the US and EU with conditions such as heart attack, pneumonia, flu, bronchitis, asthma, or broken bones.
Risk of venous thromboembolism
A significant proportion of these patients are at risk of venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism, while in the hospital and up to six weeks afterward. Around 70% of hospital-acquired fatal pulmonary embolism occurs in medically ill patients.
Anticoagulants delivered by intravenous drip or injection are recommended to prevent blood clots (called thromboprophylaxis) in medically ill patients while in hospital, but guidelines do not recommend any use of anticoagulants post-discharge.
However, after leaving the hospital, the rate of symptomatic VTE more than doubles over the first 21 days and is associated with a five-fold increased risk of fatal pulmonary embolism within 30 days post-discharge.
Patients were randomly allocated to a 45-day course of either once daily oral rivaroxaban 10 mg (7.5 mg in patients with reduced kidney function) or placebo at the time of hospital discharge. The primary efficacy outcome was symptomatic VTE and VTE-related death. The principal safety outcome was major bleeding.
The final analysis included 12,019 patients, of whom 11,962 (99.5%) had taken at least one dose of study drug. The average age was 69.7 years, and 48% were female.
Four in ten patients had been admitted to hospital for heart failure, 27% for respiratory insufficiency, 17% for infectious disease, 14% for ischaemic stroke, and 2% for inflammatory disease.
During the 45-days post-discharge, 50 (0.83%) patients taking rivaroxaban had symptomatic VTE or died from VTE-related causes compared to 66 (1.1%) taking a placebo (p=0.136).
When examining symptomatic VTE only, which included lower extremity DVT and non-fatal pulmonary embolism, there were fewer events with rivaroxaban (0.18%) compared to placebo (0.42%; hazard ratio [HR] 0.44, 95% confidence interval [CI] 0.22-0.89, p=0.023).
The researchers also examined an exploratory secondary composite endpoint of symptomatic VTE and all-cause mortality and found that 1.3% of patients taking rivaroxaban experienced an event compared to 1.78% of patients in the placebo group (HR 0.73, 95% CI 0.54-0.97, p=0.033).