Three patient groups were enrolled in the PREVENT trial — medical, surgical, and trauma patients — but it's unclear if the primary and secondary outcomes of the study were different among these three patient groups. Medical patients who received IPC represent about 78% of the patients enrolled. Surgical and trauma patients accounted for only 14% and 8%, respectively.
In comparison, a large randomized study assessing patients with stroke, known as CLOTS III, published in The Lancet, showed IPC was effective in reducing VTE in stroke patients with an average age of 78. The CLOTS III patients were older than the patients in the PREVENT study (average age of 58).
More data may be needed to determine whether the fact that patients in the PREVENT study were younger and in better health also meant that they may have had lower risk of bleeding and VTE — and so didn't need IPC. Without a VTE risk assessment, it is unclear.
In 2018, Lobastov and other researchers conducted a similar study to CLOTS III, finding benefits of IPC with high-risk surgical patients for dual modality (in combination with graduated compression stockings). The authors also recommended IPC for lower risk patients (a 5 or 6 on the Caprini Risk Assessment scale).
Recently, Lobastov expressed concerns about the PREVENT study using a mixed population of medical, surgical, and trauma patients. "The risk of VTE with trauma patients can be higher," he said. "We chose to use one population," referring to a trial of 507 surgical patients, the results of which were presented at the 2019 European Venous Forum in Zurich, Switzerland.
The trial found very different outcomes than the PREVENT trial. Lobastov concluded that "the combination of IPC and standard prophylaxis reduced the incidence of postoperative VTE in patients at extremely high risk without increasing rates of leg skin injury or bleeding."