Heparin versus Warfarin for Lupus

posted in Heart attacks, strokes & blood clots on October 4, 2023 by

Gavin Abson

Updated December 29, 2023

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Lupus can cause blood clots in many different ways. In addition, lupus patients are at higher risk of heart attacks and strokes. Therefore, drugs that thin out the blood (anticoagulants) are often needed. Heparin and warfarin are two examples.

This blog on “Heparin vs Warfarin in Lupus” was edited and contributed to by Donald Thomas, MD; author of “The Lupus Encyclopedia.” Parts of this blog post come from “The Lupus Encyclopedia: A Comprehensive Guide for Patients and Health Care Providers, edition 2“

Doctors commonly use anticoagulant medications like heparin and warfarin to manage clotting issues in lupus patients. In this article, we will compare heparin and warfarin for lupus, exploring their mechanisms, benefits, considerations, and which may be more suitable for individuals with this autoimmune condition.

Understanding Heparin and Warfarin

Heparin:
Heparin, an injectable blood thinner (known as an anticoagulant), rapidly prevents blood clot formation. It primarily works by inhibiting the action of clotting factors in the blood. Medical professionals frequently employ it in acute scenarios, such as within hospitals or during surgeries, to prevent or treat blood clots. In lupus patients, doctors prescribe it most commonly to treat a condition called antiphospholipid syndrome (APS). APS can cause recurrent blood clots or pregnancy complications.

Warfarin:
Warfarin is an oral anticoagulant that works by interfering with the body’s ability to use vitamin K, which is necessary for blood clotting. It has a delayed onset of action compared to heparin and is typically used for long-term anticoagulation. Like heparin, doctors use it most commonly to treat APS in lupus patients.

Comparing Heparin and Warfarin for Lupus

1. Speed of Action:
   Heparin: Acts quickly, making it suitable for immediate clot prevention or treatment.
   Warfarin: Has a slower onset of action and may take several days to achieve therapeutic levels.
2. Administration:
   Heparin: Requires injections, often administered in a hospital or clinical setting.
   Warfarin: Taken orally as a pill, making it more convenient for long-term use.
3. Monitoring:
   Heparin: Requires frequent monitoring of blood clotting parameters, such as activated partial thromboplastin time (aPTT).
   Warfarin: Healthcare providers need to regularly monitor the international normalized ratio (INR) to ensure they maintain therapeutic levels.
4. Reversibility:
   Heparin: Protamine sulfate can quickly reverse its effects.
   Warfarin: Reversal is more complex and may involve vitamin K administration.
5. Suitability for Lupus:
   Heparin: Usually preferred during acute blood clots or in situations requiring rapid anticoagulation. Doctors prescribe heparin instead of warfarin in pregnant women with antiphospholipid syndrome (APS). Warfarin causes birth defects.
   Warfarin: More commonly used for long-term anticoagulation in lupus patients with a history of clotting issues. Doctors most commonly prescribe it for APS patients to take, often for their entire lives.

Considerations for Lupus Patients

Lupus patients and their healthcare providers must consider several factors when choosing between heparin and warfarin:

1. Disease Activity:
   The choice may depend on the severity of lupus activity and whether there is a need for acute treatment.
2. Thrombotic Risk:
   Patients with a history of recurrent thrombosis may benefit from long-term warfarin therapy. Doctors prescribe heparin and warfarin as the drugs of choice for antiphospholipid syndrome. They avoid other oral blood thinners called directly acting oral anticoagulants (DOAC). Dabigatran, rivaroxaban, apixaban, and edoxaban are examples of DOACs. DOACs may increase the risk of blood clots in APS.
3. Convenience:
   Consider the patient’s preferences and ability to comply with injections or oral medication.
4. Monitoring:
   Lupus patients may need frequent monitoring regardless of the chosen anticoagulant to ensure proper dosing and minimize complications.
5. Individual Factors:
   Individualize the decision, considering factors such as age, comorbidities, and the risk of bleeding.

Warfarin Section in The Lupus Encyclopedia, edition 2

Here is the section regarding the use of warfarin in Dr. Thomas’ 2nd edition of The Lupus Encyclopedia. This gives you more in-depth information:

People who develop APS blood clots are at high risk of them recurring and need life-long blood thinners such as warfarin (Coumadin) or heparin. People who take warfarin must get a blood test called a PT/INR (prothrombin time and international normalized ratio) at regular intervals to ensure their warfarin is dosed correctly. A normal INR (without warfarin) is about 1.0, and this measurement increases when someone takes warfarin. The higher above 1.0, the thinner the blood is. Usually, the doctor tries to keep the/INR between 2.0 and 3.0 for most APS patients.

For patients with blood clots in their arteries (arterial thrombosis), a higher INR of 3.0 to 4.0 may be recommended. Low-dose aspirin (81 mg) daily with warfarin at standard dosing (INR of 2.0–3.0) is an alternative for arterial blood clots. As of 2020, these recommendations are supported by the 16th International Congress on Antiphospholipid Antibodies Task Force, although some APS experts recommend an INR of 2.0–3.0 in all patients.

If the blood is too thin (has too high of an INR) due to warfarin, the person is at risk of bleeding, and the warfarin dose must be lowered. If the INR level is too low, the person is at risk of blood clots, and the amount needs to increase.

Measuring the INR

Fortunately, there are now devices that people can use at home to measure the INR and enable them to adjust their own warfarin. This has greatly simplified warfarin treatment. Most APS patients who take warfarin or heparin regularly have a much lower chance of developing recurrent blood clots. However, they are at increased risk of bleeding due to their medication and should take necessary precautions against this possibility.

It is essential for people taking warfarin to learn as much as they can about what can interfere with warfarin. For example, vitamin K-rich foods, such as many green vegetables, will keep warfarin from working correctly. A person on warfarin should, therefore, learn to control their vitamin K intake since any change in vitamin K intake can affect the INR.

Ideally, a person on warfarin should not smoke cigarettes or drink alcohol since both affect warfarin levels. In addition, many drugs will either increase or decrease the INR, so it should be checked soon after any medication changes.

Stopping Warfarin

Taking warfarin for the rest of your life can be burdensome. Therefore, many patients ask if they can stop their blood thinner if they have not had a blood clot in a while. Several studies have addressed this question in patients with primary APS. These studies have had mixed results. Two studies showed a high risk for recurrent blood clots after warfarin was stopped, sometimes with dangerous effects such as catastrophic APS (discussed later in this chapter) and even death. Since SLE further increases the risk for blood clots, the decision to stop blood thinners in lupus APS patients should be approached cautiously.

The medication hydroxychloroquine (Plaquenil) may help APS. Hydroxychloroquine can reduce aPL antibody production and blood clots in SLE.

APS patients are more likely to have low vitamin D levels. Having SLE worsens vitamin D deficiency due to the need to use sunscreen and avoid ultraviolet (UV) light, which is necessary to produce vitamin D. Low vitamin D levels may increase the risk of blood clots, and some studies suggest that vitamin D supplementation may help lower this risk.

Alternative Blood Thinners

It is enticing to use newer blood thinners (instead of warfarin) that do not require frequent monitoring. These drugs are commonly called direct oral anti-coagulants (DOACs). They include rivaroxaban (Xarelto), dabigatran (Pradaxa), apixaban (Eliquis), and edoxaban (Savaysa). A study called TRAPS (Trial on Rivaroxaban in AntiPhospholipid Syndrome) was stopped midway through when 22% of the APS patients taking rivaroxaban developed dangerous blood clots; only 3% of those taking warfarin did. A 2020 French paper reported two patients who developed catastrophic antiphospholipid syndrome shortly after starting rivaroxaban. Therefore, DOACs should be avoided in APS.

Suppose, though, that someone has a venous (vein) blood clot,  and the first blood test result shows 1 or 2 APLAs. In that case, if the person was treated with a DOAC (a common treatment for venous clots) it is acceptable to continue the DOAC until a confirmatory blood test is done three months later. APS requires a repeatedly elevated APLA, and false-positive results can occur. But if the repeat test is positive, the DOAC should be changed to warfarin.

If, however, the patient with the venous blood clot has triple-positivity (three different positive APLAs). Then heparin or warfarin should be used, rather than a DOAC. This is because triple-positivity is less likely to be a false positive and carries a high risk for blood clot recurrence if not taking heparin or warfarin. Even so, some patients with triple positivity might insist on taking a DOAC. In that case, a brain MRI is recommended to ensure no evidence of decreased blood supply or history of stroke. If any of these are present, warfarin or heparin should continue to be recommended, instead of a DOAC.

Low Platelet Count

Some APS patients have low plt counts, but they do not increase bleeding. While it would be correct to stop warfarin in most people with low plts (low plts usually increase bleeding), warfarin is usually continued in patients with APS-associated thrombocytopenia.

In the management of lupus-related clotting issues, the choice between heparin and warfarin depends on various factors, including the urgency of treatment, patient preferences, and individual health characteristics. Doctors often favor heparin for its rapid action, while they frequently choose warfarin for long-term anticoagulation. Healthcare providers and patients should collaborate closely to determine the most suitable anticoagulant therapy for lupus, with regular monitoring and adjustments as necessary to ensure optimal outcomes while minimizing risks.

The above is copyrighted by Johns Hopkins University Press

In the management of lupus-related clotting issues, the choice between heparin and warfarin depends on various factors, including the urgency of treatment, patient preferences, and individual health characteristics. Doctors often favor heparin for its rapid action, while they frequently choose warfarin for long-term anticoagulation. Healthcare providers and patients should collaborate closely to determine the most suitable anticoagulant therapy for lupus, with regular monitoring and adjustments as necessary to ensure optimal outcomes while minimizing risks.

For more in-depth information on heparin, warfarin, other blood thinners and antiphospholipid syndrome in lupus:

Read chapter 9 of The Lupus Encyclopedia, edition 2

Look up your symptoms, conditions, and medications in the Index of The Lupus Encyclopedia

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Dr. Donald Thomas, MD edited and contributed to this blog post