The Butterfly study. A trial assessing acceptability and safety of using a subcutanous catheter to administer enoxaparin (Clexane) in patients requiring long-term therapy for treatment or prevention of blood clots.

A prospective crossover trial comparing enoxaparin (Clexane) therapy using subcutaneous injections (current standard of care) and a subcutaneous indwelling catheter (which can remain in place up to 7 days). This is a non-randomised trial, therefore all participants will have a subcutaneous catheter inserted, and then revert back to subcutaneous injections (the current standard of care). The trial period will run over approximately 3 weeks. The subcutaneous catheter will be inserted on day 1 and remain in place for 7 days (unless removal is required before this time). Participants will then continue to administer enoxaparin by subcutaneous injections. All participants will be receiving enoxaparin by subcutaneous injections, and require ongoing therapy for a minimum of 4 weeks from study entry. Patients on either therapeutic (1mg/kg once or twice daily) or prophylactic enoxaparin (20mg, 40mg or 60mg) therapy will be included. The subcutaneous catheter will be inserted by nursing staff, and there will be 3 reviews (1 nursing only, 2 nursing and medical review) over the 7 day period using the catheter to assess the site and participant. Participants will be taught to self-administer enoxaparin using the subcutaneous catheter. There will be a nurse and doctor available by telephone on other days to trouble-shoot or answer any questions. Peak anti-Xa activity will be measured at 3 timepoints (Days 2, 5 and 7) with the subcutaneous catheter. The catheter will then be removed and they will continue on subcutaneous injections for the remainder of the trial follow-up period with 2 further peak anti-Xa levels measured following a period of 5 days using subcutaneous injections. Participants will be closely monitored for both thrombosis and bleeding during the period of using the subcutaneous device (3 in person assessments and additional phone calls as required), and monthly by telephone for 3 months after. Patient and nursing assessments will be completed throughout the 3 week study period to assess acceptability of, and any complications associated with subcutaneous catheters. Following the initial study period, there is the option to continue onto the long-term extension phase. This allows participants to continue using the subcutaneous catheters with 4-weekly medical review, and allows participants to learn to self-inset the subcutaneous catheters. This phase will extend up to 24 months. Participants will enter the follow-up phase after completing the long term extension. This amendment was implemented after 3 participants had been recruited. There is an optional qualitative 30-45 minute interview conducted via zoom to further explore the patient experience with enoxaparin. This was implemented after 4 participants had been recruited.