Which stroke patients gain most from intermittent pneumatic compression: Further analyses of the CLOTS 3 trial

Background: The CLOTS 3 trial showed that intermittent pneumatic compression (IPC) reduced the risk of DVT and improved survival after stroke. Aims: To provide additional information which may help clinicians target IPC on the most appropriate patients by exploring the variation in its effects on subgroups defined by predicted prognosis. Methods: A multicentre, parallel group, randomized trial enrolled immobile acute stroke patients and allocated them to IPC or no IPC. The primary outcome was proximal DVT at 30 days. Secondary outcomes at six-months included survival, disability, quality of life, and hospital costs. We stratified patients into quintiles according to their predicted prognosis at randomization, based on the Six Simple Variable model. Results: Between December 2008 and September 2012, we enrolled 2876 patients in 94 UK hospitals. Patients with the best predicted outcome had the lowest absolute risk of proximal DVT (6·7%) and death by six-months (9·3%). Allocation to IPC had little effect on DVT, survival, disability, quality of life, hospital length of stay, or costs. In patients with the worst predicted outcomes, the overall risk of DVT and death was 16·0% and 51·3%, respectively. IPC reduced DVT (odds reduction 34%) and improved survival 17% and significantly increased length of stay and hospital costs. In the three intermediate quintiles, IPC reduced the odds of DVT (35-43%) and improved survival (11-13%). Disability and quality of life at six-months depended on baseline severity but was not influenced significantly by IPC. Conclusions: IPC appears to reduce the risk of DVT and probably improves survival in all immobile stroke patients, other than the fifth with the best prognosis. It therefore seems reasonable to recommend that IPC should be considered in all immobile stroke patients, but that the final decision should be based on a judgment about the individual's prognosis. In some, their prognosis for survival with an acceptable quality of life will be so poor that use of IPC might be considered futile, while at the other end of the spectrum, patients' risk of DVT, and of dying from VTE, may not be high enough to justify the modest cost and inconvenience of IPC use.