Effectiveness of Intermittent Pneumatic Compression in Reduction of Risk of Deep Vein Thrombosis in Patients Who Have Had a Stroke (CLOTS 3): A Multicentre Randomised Controlled Trial

Study Questions:

What is the effectiveness of intermittent pneumatic compression (IPC) in reducing the risk of deep vein thrombosis (DVT) in patients who have had a stroke?


The CLOTS 3 trial was a multicenter parallel group randomized trial assessing IPC in immobile patients (i.e., who cannot walk to the toilet without the help of another person) with acute stroke. The investigators enrolled patients from day 0 to day 3 of admission and allocated them via a central randomization system (ratio 1:1) to receive either IPC or no IPC. A technician who was masked to treatment allocation did a compression duplex ultrasound (CDU) of both legs at 7–10 days and, wherever practical, at 25–30 days after enrollment. Caregivers and patients were not masked to treatment assignment. Patients were followed up for 6 months to determine survival and later symptomatic venous thromboembolism. The primary outcome was a DVT in the proximal veins detected on a screening CDU or any symptomatic DVT in the proximal veins, confirmed on imaging, within 30 days of randomization. Patients were analyzed according to their treatment allocation.


Between December 8, 2008, and September 6, 2012, 2,876 patients were enrolled in 94 centers in the United Kingdom. The included patients were broadly representative of immobile stroke patients admitted to the hospital, and had a median age of 76 years (interquartile range, 67–84). The primary outcome occurred in 122 (8.5%) of 1,438 patients allocated IPC and 174 (12.1%) of 1,438 patients allocated no IPC; an absolute reduction in risk of 3.6% (95% confidence interval [CI], 1.4–5.8). Excluding the 323 patients who died before any primary outcome and 41 without any screening CDU, the adjusted odds ratio for the comparison of 122 of 1,267 patients vs. 174 of 1,245 patients was 0.65 (95% CI, 0.51–0.84; p = 0.001). Deaths in the treatment period occurred in 156 (11%) patients allocated IPC and 189 (13%) patients allocated no IPC died within the 30 days of the treatment period (p = 0.057); skin breaks on the legs were reported in 44 (3%) patients allocated IPC and in 20 (1%) patients allocated no IPC (p = 0.002); falls with injury were reported in 33 (2%) patients in the IPC group and in 24 (2%) patients in the no-IPC group (p = 0.221).


The authors concluded that IPC is an effective method of reducing the risk of DVT and possibly improving survival in a wide variety of patients who are immobile after stroke.


This trial shows that IPC (delivering sequential circumferential compression via thigh-length sleeves at a frequency determined by the venous refill time), applied to immobile stroke patients ,is safe and reduces the risk of proximal DVT (primary outcome), symptomatic DVTs (proximal or calf), and all DVTs (symptomatic or asymptomatic, proximal or calf). Furthermore, there was a potential improvement in survival. Overall, the results of the CLOTS 3 trial provide reassurance to clinicians who choose to prescribe IPCs to immobilized medical inpatients with and without stroke.

Clinical Topics: Noninvasive Imaging, Pulmonary Hypertension and Venous Thromboembolism, Vascular Medicine, Echocardiography/Ultrasound

Keywords: Odds Ratio, Stroke, Great Britain, Disease Management, Venous Thromboembolism, Intermittent Pneumatic Compression Devices, Inpatients, Caregivers, Blood Coagulation, Cardiology, Venous Thrombosis, Confidence Intervals, Ultrasonography

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