Mike: Hello, I'm Mike Clarke, podcast editor for the Cochrane Library. The single most common, preventable cause of in-hospital death is a hospital-acquired venous thromboembolism; making this an important target for prevention when people are admitted to hospital. An updated Cochrane Review from January 2022 looks at the evidence for one of the possible interventions, which combines anti-coagulant drugs with intermittent pneumatic leg compression to prevent these blood clots. Stavros Kakkos from the University of Patras in Greece tells us more.

Stavros: A variety of methods have been used over the last 80 years and more to try to prevent hospital-acquired venous thromboembolism, including anticoagulants and leg compression using elastic stockings or intermittent pneumatic pressure. Mechanical intermittent pneumatic leg compression, called IPC for short, reduces sluggish blood flow, while drugs such as aspirin and anticoagulants such as low molecular weight heparin, reduce blood clotting. Unfortunately, the best preventive methods available today are effective in only about two thirds of cases when used on their own. An alternative might be to combine different methods of prophylaxis, particularly in high-risk patients, and our review has shown that these combinations might be helpful.
We investigated whether combining IPC and anticoagulation is more effective than using either on its own, and whether the combination might be less safe, taking into account the possibility of an increased risk of bleeding. Overall, we found 34 trials with nearly 15,000 participants, most of whom had a high-risk procedure or condition, which included orthopedic surgery, urology, cardiothoracic, neurosurgery, trauma, general surgery and gynaecology.
Using data from 19 studies, with approximately 5500 patients, we found that pulmonary embolism was lower in the patients allocated to IPC combined with anticoagulation than for patients in the IPC alone group, falling from 16 per thousand to 7 per thousand. Similarly, deep vein thrombosis, or DVT, was lower in the patients allocated to the combined strategy than for patients in the IPC alone group, at 20 per thousand rather than 38 per thousand. On the other hand, adding anticoagulation to IPC increased the risk for any bleeding compared to IPC alone, from about 10 to 55 in every thousand patients. Major bleeding followed a similar pattern, with an increase from 3 to 19 per thousand.
Looking at the combination of IPC and anticoagulation versus anticoagulation alone, there were 15 studies with 6700 patients. These showed that the combination reduced the incidence of both pulmonary embolism and DVT, with bleeding being similar in the two groups.
In summary, this latest update of our Cochrane Review supports current guidelines, which recommend the use of combined modalities in hospitalised patients at risk of developing venous thromboembolism. However, uncertainties remain and will require resolving through more studies on the role of combined modalities.

Mike: If you'd like to read more about the current evidence on these combined modalities, and watch out for the next update of this review, just go to Cochrane Library dot com and search 'pneumatic leg compression and thromboembolism' to find it.