Testing whether taking aspirin before surgery can help prevent blood clots in people having orthopaedic operations

ISRCTN	ISRCTN59381053
DOI	https://doi.org/10.1186/ISRCTN59381053
Sponsor	Sultan Qaboos University Hospital
Funder	Investigator initiated and funded

Submission date: 09/03/2026
Registration date: 10/03/2026
Last edited: 10/03/2026

Recruitment status: Recruiting
Overall study status: Ongoing
Condition category: Surgery

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Not provided at time of registration

Contact information

Dr Humaid AL Farri
Principal investigator, Scientific

Sultan Qaboos University Hospital
Muscat
112
Oman

Phone	+968 93319144
Email	humaid44@squ.edu

Dr Muhannad ALOthmani
Public

Sultan Qaboos University Hospital
Muscat
112
Oman

Phone	+968 96774848
Email	r23126@resident.omsb.org

Study information

Primary study design	Interventional
Allocation	N/A: single arm study
Masking	Open (masking not used)
Control	Active
Assignment	Single
Purpose	Prevention
Scientific title	Pre-operative ASpirin for Thromboembolism prophylaxis (PAST) trial: A phase II open-label single-arm trial to evaluate the efficacy and safety of aspirin in preventing thromboembolism in patients undergoing orthopaedic surgery
Study acronym	PAST
Study objectives	Primary objective: To evaluate the efficacy of aspirin in preventing the incidence of venous thromboembolism (VTE) in patients undergoing orthopedic surgery (Spine, MSK tumor and Hip/Knee arthroplasty procedures) Secondary objectives: 1. To assess the safety of aspirin by monitoring bleeding complications (major and minor) 2. To evaluate the incidence of thromboembolic events (DVT and PE) 3. To assess functional recovery and quality of life post-surgery 4. To evaluate the incidence of adverse events (e.g., gastrointestinal issues, renal complications)
Ethics approval(s)	Submitted 05/11/2025, Medical Research Ethics Committee (MREC) (Sultan Qaboos University Hospital, Muscat, 112, Oman; +968 2414 3468; mrec@squ.edu.om), ref: 046/2025
Health condition(s) or problem(s) studied	Preventing thromboembolism in patients undergoing orthopedic surgery
Intervention	Patients will be administered aspirin (100 mg ) as per protocol, starting within 12 hours pre-surgery stat dose of 100 mg. then 100 mg BID for the next 30 days post operation. Adherence to the medication will be monitored, and any issues with compliance will be documented. Follow-Up Visits: Post-surgical clinical visits will take place at 2 weeks, 4 weeks and 8 weeks post-surgery, or earlier if clinically indicated. Monitoring: Regular monitoring for bleeding (via clinical examination and Laboratory) and thromboembolic events (via ultrasound for DVT, CT or VQ scan for PE)
Intervention type	Drug
Phase	Phase II
Drug / device / biological / vaccine name(s)	aspirin
Primary outcome measure(s)	The incidence of VTE in patients undergoing orthopedic surgery (Spine, MSK tumor and Hip/Knee arthroplasty procedures) measured using rate/ numbers of thromboembolic events at from day 1 post surgery until 3 months post surgery
Key secondary outcome measure(s)	Hemoglobin level measured using laboratory hemoglobin test at 12 hours pre surgery, post-operative day 1, post-operative day 3, and any time if clinically indicated Baseline hematocrit measured using laboratory hematocrit test at 12 hours pre surgery Estimated intra-operative blood loss measured using surgical estimation recorded by the anaesthetist and surgeon at during surgery Post-operative clinical signs of bleeding measured using daily clinical examination of the wound for hematoma, excessive oozing or ecchymosis at post-operative day 1 until discharge or as clinically indicated Participant-reported bleeding symptoms measured using symptom questioning at follow-up visits at 2 weeks, 6 weeks, 3 months History of gastrointestinal risk factors measured using medical history review for peptic ulcer disease, dyspepsia or H. pylori infection at 12 hours pre surgery Gastrointestinal symptoms potentially related to aspirin measured using symptom questioning for dyspepsia, heartburn, nausea, vomiting, abdominal pain or melena at 2 weeks, 6 weeks, 3 months Concomitant use of NSAIDs or corticosteroids measured using medication review at 12 hours pre surgery, 2 weeks, 6 weeks, 3 months Serum creatinine measured using laboratory serum creatinine test at 12 hours pre surgery, post-operative day 3, 6 weeks, 3 months Estimated glomerular filtration rate (eGFR) measured using laboratory eGFR test at 12 hours pre surgery, post-operative day 3, 6 weeks, 3 months
Completion date	21/06/2026

Eligibility

Participant type(s)
Age group	Mixed
Lower age limit	18 Years
Upper age limit	90 Years
Sex	All
Target sample size at registration	200
Key inclusion criteria	1. Patients aged 18-90 years 2. Scheduled for elective or emergency orthopedic surgery (hip replacement, knee replacement, spine, and tumor procedures) 3. Able and willing to provide informed consent 4. No contraindications to aspirin use (e.g., active bleeding disorders, aspirin allergy)
Key exclusion criteria	1. Pre-existing DVT or pulmonary embolism 2. Current use of other anticoagulants or antiplatelet agents 3. Significant renal or hepatic insufficiency 4. Pregnancy or breastfeeding
Date of first enrolment	08/03/2026
Date of final enrolment	14/06/2026

Locations

Countries of recruitment

Oman

Study participating centres

Results and Publications

Individual participant data (IPD) Intention to share	No
IPD sharing plan summary	Not expected to be made available
IPD sharing plan

Editorial Notes

10/03/2026: Trial's existence confirmed by Sultan Qaboos University Hospital.