A RCT to Establish the Effectiveness of Intermittent Pneumatic Compression to Prevent Post Stroke DVT

Design: Multicentre randomised controlled trial with observer blinded assessment of the primary outcome.

Setting: Stroke units in the UK. Identification of eligible patients, consent, recruitment, delivery and monitoring of allocated treatment will occur within the unit. Screening compression doppler ultrasounds will occur in the radiology department or vascular laboratory mainly during hospital admission although in the minority of patients who are discharged from hospital they may have these tests as an outpatient. Six month follow up will occur in their place of residence via a postal or telephone questionnaire.

Target population: Patients (16 years or over) admitted to hospital with an acute stroke who are immobile and therefore at significant risk of developing a deep venous thrombosis.

Health technologies being assessed: The trial will compare the outcomes of patients receiving Routine care plus Intermittent Pneumatic Compression (IPC) vs. Routine care and avoiding IPC. Patients allocated to IPC will be fitted with thigh length IPC sleeves although if these are not well tolerated, for instance because of heavy soiling due to faecal incontinence, below knee sleeves can be substituted. Ideally IPC will be worn both day and night for 30 days from randomisation OR until a second screening doppler ultrasound (if after 30 days). Routine care is likely to include general measures to reduce risk of DVT including, adequate hydration, routine use of aspirin in patients with ischaemic stroke and early mobilisation. It may also include routine use of graduated compression stockings (GCS) if these are shown to be effective in the ongoing CLOTS Trials 1 \& 2. Participating centres will be asked to ensure that the standard care specific to their institution is applied equally rigorously to patients in the trial irrespective of their treatment allocation. Collaborators will be permitted to use these interventions where they feel this is clinically justified - we will monitor use of antithrombotics and GCS to ensure it is balanced in the two treatment arms.

Measurement of costs and outcomes: The primary outcome will be the "presence of definite or probable symptomatic or asymptomatic DVT in the veins behind the knee or in the thigh detected on either of two screening compression Doppler ultrasound scans (performed at about 7-10 days and 25 - 30 days as part of the research) or contrast venography or MRI(only if clinically indicated) within 30 days of randomisation". This is regarded as a clinically important outcome, acceptable to patients and staff and has been shown to be practical to collect in the vast majority of patients in the ongoing CLOTS Trials 1 \& 2. Secondary outcomes measured in hospital and collected at hospital discharge by reviewing the casenotes will include: death within 30 days; Presence of definite or probable DVT in the popliteal or femoral veins detected on a screening Compression Doppler ultrasound scan which had not been suspected clinically before the scan,Definite (i.e. excluding probable DVTs) symptomatic or asymptomatic DVT in the popliteal or femoral veins detected on either a Compression Doppler ultrasound scan or contrast venography or MRI direct thrombus imaging within 30 days of randomisation; Any definite or probable symptomatic or asymptomatic DVT (i.e. including DVTs which only involve the calf veins); Confirmed fatal or non-fatal PE; Adherence to allocated treatment.

Others secondary outcomes measured by either postal or telephone questionnaire at six months will include: death from any cause, place of residence, post discharge DVT, PE, post DVT syndrome, disability, and health related quality of life. These will be supplemented by follow-up for survival via GPs.

Sample size: We plan to recruit about 2000 patients. The Trial will have > 90% power (alpha 0.05) to identify an absolute reduction of risk of our primary outcome of 4% (10% to 6%). The frequency of our primary outcome is estimated from the ongoing CLOTS Trials 1 \& 2 which use the same entry criteria and methods of follow up. The estimated effect size (odds reduction = 43%) is based on the treatment effects in the systematic review of previous stroke trials (odds reduction = 48%) attenuated by the delays in applying the treatment due to trial recruitment and realistic estimates of adherence to the allocated treatment. If the event rate in both treatment groups combined is lower than expected the Trial Steering Committee may decide to increase the recruitment target. We aim to enrol at least 1500 patient on Days 0-2 after stroke onset. This will provide greater than 80% power to detect a reduction in proximal DVT from 10% to 6% in patients enrolled on Days 0-2. If the proportion enrolled after Day 2 exceeds 25% of the total then the Trial Steering Committee will consider raising the overall target beyond 2000 to ensure that at least 1500 are recruited on Days 0-2. This should help ensure that we do not miss a real treatment effect because of delays in recruitment. If the trial shows that IPC is effective in reducing the risk of DVT after stroke it is likely that IPC treatment will be started earlier than in the trial.

Flow from patients perspective

1. Approach by clinical staff who will give verbal and written information about trial
2. Completion of consent form
3. Informed of treatment allocation
4. Start of treatment - application of intermittent pneumatic compression in half of patients. This involves nursing staff measuring the patients thigh diameter, fitting the correct size of sleeves and checking the patients legs three times per day to ensure there are no problems with the skin developing.
5. At 7-10 days after recruitment the patient goes to X Ray department to have a screening Doppler ultrasound of both legs. The IPC is removed prior to them leaving the ward and replaced on their return.
6. At 25-30 days after recruitment the patients go to X Ray department to have a second screening Doppler ultrasound of both legs. If already discharged from hospital this may involve an outpatient appointment. Patient transport is provided if this is required.
7. At 30 days the IPC (if allocated) is finally removed unless it has been removed earlier for a specific reason (see protocol)
8. At about 6 months after recruitment the patient will receive a short postal questionnaire to find out their current functional status, whether they have had any clots since hospital discharge and what blood thinning medication they might be taking.