NCT07559643Not yet recruiting
The OAT Trail: The Obesity Anti-Coagulation Thromboprophylaxis Trial.
A Prospective, Randomised Controlled Trial Comparing Weight-based Tinzaparin Versus Weight-based Enoxaparin for Peri-operative Thromboprophylaxis in Patients Undergoing Bariatric Surgery: Evaluation of Anti-Xa Levels and Clinical Outcomes.
Source: ClinicalTrials.gov · Last updated 18 May 2026
Brief summary (registry, in English)
Blood clots in the legs or lungs (called venous thromboembolism or VTE) are one of the most serious complications after weight loss surgery. Most blood clots occur after patients go home from hospital, within the first 30 days after surgery. To prevent blood clots, all patients having weight loss surgery receive a daily blood-thinning injection for 21 days after their operation. Two blood-thinning injections are currently used at St Vincent's University Hospital for this purpose: enoxaparin (Clexane®) and tinzaparin (Innohep®). Both belong to a group of medicines called low molecular weight heparins (LMWHs). Patients with obesity process these medicines differently to the general population, and previous studies from our hospital have shown that fewer than 53% of patients achieve adequate blood-thinning levels with either injection when measured by a blood test called an anti-Xa level. Patients will be randomly assigned (like a coin toss) to receive either tinzaparin or enoxaparin for 21 days after their surgery. Both injections are already in routine use at this hospital. A single extra blood sample will be taken on the second day after surgery to measure the anti-Xa level, which tells us whether the injection is providing adequate protection against blood clots. This blood sample will be taken at the same time as routine post-operative blood tests so that no additional blood draws are required. The study will also look at rates of blood clots and bleeding events within 30 days of surgery, and will ask patients to complete a short questionnaire at their six-week follow-up appointment about their experience with the injection.
- Status (registry)
- Not yet recruiting
- Study type
- Interventional
- Enrollment
- 180 (estimated)
- First submitted
- 23 Apr 2026
- Start date
- 1 Aug 2026
- Primary completion date
- 1 Aug 2026
- Lead sponsor
- University College Dublin
- Diseases
- Obesity
- NCT number
- NCT07559643
What you commit to
- Study type: Interventional
- Planned participants: 180
- From 1 Aug 2026 to the primary completion date, 1 Aug 2026
- 1 site in 1 country
- Visits and tests: ask the trial team, the registry does not list them
Built from the registry fields of ClinicalTrials.gov. It describes the study, not your situation.
Who cannot take part
Copied verbatim from ClinicalTrials.gov and grouped by topic. Only the trial team decides who can take part.
Lab values
- Current therapeutic anticoagulation for any indication Known allergy or hypersensitivity to tinzaparin, enoxaparin, heparin, or any heparin-derived product, including documented heparin-induced thrombocytopaenia (HIT) Any other contraindication to LMWH therapy Severe renal impairment (eGFR \<30 mL/min/1.73m²) Known haematological disorder or coagulopathy Pregnancy, breastfeeding, or planning pregnancy during the study period Active major bleeding or high bleeding risk at the discretion of the treating clinician Inability to provide written informed consent Participation in another interventional clinical study within 30 days prior to enrolment
Who the study is looking for
- Age ≥18 years
- BMI ≥40 kg/m², or BMI ≥35 kg/m² with at least one obesity-related comorbidity (type 2 diabetes, hypertension, obstructive sleep apnoea, dyslipidaemia, or metabolic dysfunction-associated steatotic liver disease (MASLD))
- Scheduled to undergo laparoscopic bariatric surgery (sleeve gastrectomy or gastric bypass) at St Vincent's University Hospital, Dublin, Ireland
- Capacity to provide written informed consent
Age in the registry: 18 years to - · Sex: All · Does not accept healthy volunteers
Sites (1)
Sites in registry order. Pick your city on the disease page to sort them by distance.
| Site | City | Country | Site status |
|---|---|---|---|
| St Vincent's University Hospital Coordinator of this site? Confirm its status | Dublin | Ireland | Unknown status |
This page is information, not medical advice. Discuss any trial with your doctor.