Using genetic testing to personalize warfarin treatment after heart valve replacement surgery in Qatar

ISRCTN	ISRCTN25354156
DOI	https://doi.org/10.1186/ISRCTN25354156
Sponsor	Qatar Precision Health Institute
Funder	Qatar Precision Health Institute

Submission date: 03/05/2026
Registration date: 14/05/2026
Last edited: 13/05/2026

Recruitment status: No longer recruiting
Overall study status: Completed
Condition category: Circulatory System

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Background and study aims
Warfarin is a medication taken by mouth that helps prevent blood clots. It is commonly prescribed for people after heart valve replacement surgery to reduce the risk of serious complications.
However, warfarin can be difficult to use safely. The difference between a helpful dose and a harmful one is small. It is also affected by other medications, and people respond to it very differently, so the correct dose can vary a lot from person to person.
In Qatar, doctors usually start patients on standard doses of warfarin after surgery. They then monitor blood clotting regularly using a test called the international normalized ratio (INR) and adjust the dose to keep it within a safe range. This makes managing warfarin treatment challenging.
Research has shown that a person’s genes can influence how much warfarin they need. Using genetic information could help doctors predict the right dose more accurately and make treatment safer.
This study looks at whether rapid genetic testing at the point of care can help guide warfarin dosing for patients after heart valve surgery. The goal is to improve dosing accuracy and support the routine use of personalized (genetics-based) treatment for warfarin in Qatar.

Who can participate?
Patients 18-75 years old who are indicated warfarin following heart valve replacement surgery, have not used warfarin in the past 3 months, and have have normal INR value of 0.8-1.2

What does the study involve?
The genetic testing-guided strategy (intervention group) of patients will be compared against a traditional dosing strategy (control group). In the intervention group the genetic test will be performed as soon as possible and the result will be reported 2 days before the surgery.

What are the possible benefits and risks of participating?
The study aims to implement pharmacogenetic testing in the clinical setting in Qatar, which helps in personalising anticoagulant therapy for more efficient treatment and fewer side effects.
No potential harm or anticipated risk is associated with participation. Participants would be provided with a point-of-contact in case they have any complications or adverse effects that they could report.

Where is the study run from?
Hamad Medical Corporation (Qatar)

When is the study starting and how long is it expected to run for?
January 2023 to May 2026

Who is funding the study?
Qatar Precision Health Institute (Qatar)

Who is the main contact?
Dr Rania Galal Abdel-latif, rabdellatif@qf.org.qa

Contact information

Dr Rania Abdel-latif
Principal investigator, Scientific, Public

Qatar Precision Health Institute-Qatar Science and Technology Park, Tech 1
Doha
5825
Qatar

Phone	+974 (0)70001383
Email	rabdellatif@qf.org.qa

Study information

Primary study design	Interventional
Allocation	N/A: single arm study
Masking	Open (masking not used)
Control	Historical
Assignment	Sequential
Purpose	Health services research, Prevention
Scientific title	Clinical implementation of pharmacogenetic-guided dosing of warfarin in patients with heart valve replacement in Qatar
Study objectives	This study is designed as a two-arm comparative study (prospective cohort study vs retrospective study). The study includes heart patients undergoing heart valve replacement and eligible for warfarin treatment post-surgery. The study is designed to demonstrate whether genotype-guided dose prediction improves the safety and efficacy of warfarin treatment compared to non-tailored strategies.
Ethics approval(s)	Approved 05/09/2022, Hamad Medical Corporation (Hamad Medical City, Doha, 3050, Qatar; +974 (0)66480831; AElsid@hamad.qa), ref: IRB-HMC-2021-011
Health condition(s) or problem(s) studied	Patients eligible for warfarin after heart valve replacement surgery
Intervention	The prospective cohort genotype-guided strategy (intervention group) of 150 patients will be compared against a traditional retrospective clinical dosing strategy (control group), which will be 300 patients from 01/01/2019 to 01/10/2022. The patients of the intervention group will be recruited prospectively in the heart hospital, Hamad Medical Corporation. Before being assigned to the surgery, eligible patients will be recruited in the study after signing written informed consent. The genetic test will be performed as soon as possible, and the result will be reported 2 days before the surgery.
Intervention type	Drug
Phase	Not Applicable
Drug / device / biological / vaccine name(s)	Warfarin
Primary outcome measure(s)	The percentage of time in the therapeutic range (TTR) during a 30-day timeframe, measured using the percentage of the time the patient INR is within the target range during 30 days of therapy according to the method of Rosendaal, measured at 30 days post heart valve replacement surgery The time to achieve the therapeutic INR during a 30-day timeframe, measured using the time from the initiation of warfarin therapy until the first INR reaches the treatment coagulation range, measured at 30 days post heart valve replacement surgery
Key secondary outcome measure(s)	Time to reach stable warfarin dose, measured using serial INR monitoring and dosing records (stable dose is defined as an INR within the target therapeutic range on a specified dose maintained for at least 2 consecutive days), at clinical follow-up visits between day 5 and day 30 after warfarin initiation Over-anticoagulation events measured using the incidence of INR >4.0 using laboratory INR testing at the first 4 weeks of follow-up after warfarin initiation Under-anticoagulation events measured using the incidence of INR <2.0 using laboratory INR testing at the first 4 weeks of follow-up after warfarin initiation Frequency of warfarin dose adjustments measured using prescribing and medication records by counting the number of dosage changes at the first 4 weeks after warfarin initiation Minor bleeding, major bleeding, and hemorrhagic complications measured using clinical assessment and electronic medical record documentation (bleeding events will be classified according to standard clinical definitions) at the first 4 weeks after warfarin initiation Thromboembolic events, recurrent thrombosis, and stroke incidence as indicators of lack of anticoagulation efficacy, measured using clinical assessment, imaging reports, and electronic medical record documentation at the first 4 weeks after warfarin initiation Warfarin sensitivity incidence measured using warfarin dosing records (warfarin sensitivity is defined as a stable maintenance dose of 1.5 mg/day or less on three successive clinic visits) at clinical follow-up visits within the study period
Completion date	03/05/2026

Eligibility

Participant type(s)
Age group	Mixed
Lower age limit	18 Years
Upper age limit	75 Years
Sex	All
Target sample size at registration	150
Total final enrolment	25
Key inclusion criteria	1. 18-75 years old 2. Not used warfarin in the past 3 months 3. Normal international normalised ratio (INR) value of 0.8-1.2 4. Informed consent
Key exclusion criteria	1. History of any other cardiac operation 2. Diagnosis of active cancer/haematological disorders 3. Severe renal/hepatic insufficiency 4. Abnormal thyroid function 5. Pregnancy 6. Inability to provide written consent
Date of first enrolment	22/01/2023
Date of final enrolment	04/10/2025

Locations

Countries of recruitment

Qatar

Study participating centres

Results and Publications

Individual participant data (IPD) Intention to share	No

Study outputs

Output type	Details	Date created	Date added	Peer reviewed?	Patient-facing?
Other files	version 1		05/05/2026	No	No
Protocol file	version 1		05/05/2026	No	No

Additional files

49463_ConsentForm_Eng_V1 (4) (1).pdf: Other files
49463_PROTOCOL_V1.pdf: Protocol file

Editorial Notes

11/05/2026: Study's existence confirmed by the Qatar Precision Health Institute (QPHI).