Driving awareness on deep vein thrombosis and anticoagulant therapy

Venous Thromboembolism (VTE) is associated with high morbidity, disability and fatality globally and awareness of VTE and its social burden, especially in low-income countries, is still relatively low.

VTE is a condition in which a blood clot forms most often in the deep veins of the leg, groin or arm (deep vein thrombosis 'DVT') and travels in the circulation, lodging in the lungs (pulmonary embolism 'PE').

A blood clot is a mass of coagulated blood that has formed within a blood vessel.

Blood clots can pose a serious health risk. It can lead to stroke, pulmonary embolism, loss of a limb or death, if not identified and treated properly.

Both DVT and PE are known as VTE and are dangerous and potentially-deadly medical conditions responsible for disability and one-third of deaths of hospitalised patients.

According to the American Heart Association, VTE is the third leading vascular diagnosis after heart attack and stroke, and is often overlooked as a major public health problem.

A scientific review by the World Thrombosis Day Steering Committee of the International Society on Thrombosis and Haemostasis reveals that 10 million cases of VTE occur annually across low, middle and high income countries.

Risk factors for developing VTE include family history of DVT or PE, age (older individuals are at higher risk), decreased movement such as during international flights or hospitalisation, overweight or obesity, pregnancy with multiple gestation, dehydration, stroke and cancer.

Dr Peter Ogundeji, a Consultant Haematologist, at the University College Hospital, Ibadan, says VTE can be life-threatening, noting that about one-third of people with undiagnosed and untreated VTE die.

"It is often said that an individual, after recovering from an illness, surgery or a long trip, suddenly slumps and dies. Many of these deaths are related to blood clotting problems that are undetected and unprevented.

"If a blood clot blocks the flow of blood through a blood vessel, the affected part of the body will become starved of oxygen and will stop working properly," Ogundeji explains.

He says socio-economic consequences of VTE are significant with respect to disability and costs.

Ogundeji advises that VTE risk assessment should be conducted on all hospitalised patients to gather information about their ages, medical history, medications and lifestyle factors.

According to him, such information should be used to discern a patient's potential risk ( high, moderate or low risk) for developing blood clots in the legs or lungs.

On non-pharmacological intervention to reduce an individual's risk of blood clotting, Ogundeji says being active, exercising legs during long trips, quitting smoking, losing weight and managing other health problems such as diabetes, high blood pressure and high cholesterol level, are important.

He says pharmacotherapy for VTE can differ by patient but typically includes anti-clotting medications such as blood thinners, referred to as anticoagulants, and device therapy using compression stockings.

Anticoagulants are medicines that help prevent blood clots. They are administered to patients at high risk of getting clots to reduce their chances of developing serious conditions such as stroke and heart attack.

According to an online publisher of health news, webMd.com, people with the following conditions or risk factors can also use anticoagulants: certain heart or blood vessel diseases, abnormal heart rhythm called atrial fibrillation, heart valve replacement, risk of blood clots after surgery, and congenital heart defects.

It says anticoagulants come in different forms including injections, intravenous (IV) drugs, and oral medications.

They are divided into four main groups: Vitamin K antagonists, factor Xa inhibitors, heparins, and direct thrombin inhibitors.

Vitamin K antagonists (VKA) anticoagulant work by limiting the availability of Vitamin K, a vitamin that is necessary for the blood coagulation pathway to produce clotting factors.

VKAs like warfarin come in tablet form and are taken orally. It can interact with certain foods and can cause serious interactions with many commonly-used medicines.

Regular blood monitoring (International Normalised Ratio – INR) is done to check for effectiveness and safety.

On the other hand, Heparin is an injectable anticoagulant that inhibits clotting by activating the body's anti-clotting processes, while direct thrombin inhibitors, anticoagulant, work by attaching to thrombin, keeping it from assisting clotting processes.

They include desirudin, bivalirudin and argatroban, which are given intravenously; as well as dabigatran, given orally.

In the past decade, investigators have researched into substitutes in the clotting cascade in attempts to create a safer, more efficacious and more convenient alternatives to warfarin and heparin.

The research led to the development of Factor Xa inhibitors also known as NOACs (novel oral anticoagulants) or DOAC (direct oral anticoagulants).

Factor Xa inhibitors are a type of anticoagulant that work by selectively and reversibly blocking the activity of clotting factor Xa, preventing clot formation. It has predictable anticoagulant effects and does not require routine monitoring.

Apixaban, edoxaban, fondaparinux and rivaroxaban are all Factor Xa inhibitors used to prevent and treat clotting.

A research article entitled 'Comparative Safety and Effectiveness of Oral Anticoagulants in Nonvalvular Atrial Fibrillation' published in the American Heart Association journal shows that Apixaban is associated with superior safety, effectiveness and lower mortality than VKAs, and superior safety than rivaroxaban.

Apixaban, produced by Pfizer and Bristol-Myers and sold under the brand name Eliquis, is an anticoagulant medication used to prevent a blood clot from forming in the heart of patients with an irregular heart beat (atrial fibrillation AFib) and, at least, one additional risk factor.

Eliquis is also administered to treat DVT and PE, and to prevent blood clots from reoccurring in the blood vessels of the legs or lungs.

Dr Dike Ojji, Consultant Cardiologist at the University of Abuja Teaching Hospital, Gwagwalada, says that 20 per cent of all strokes in the general population are due to Atrial Fibrillation (AFib).

Ojji notes that Non-Valvular Atrial Fibrillation (NVAF) increases risk of stroke by approximately five-fold compared to risk of stroke in patients without NVAF.

He notes that NVAF is also associated with increased severity, disability and increased risk of death.

"Apixaban demonstrated superior efficacy versus acetylsalicylic acid (ASA) without significantly increasing the risk of major bleeding.

"Apixaban demonstrates a superior stroke or systemic embolism prevention by 21 per cent, superior profile in reducing major bleeding by 31 per cent and superior reduction in all-cause mortality by 11 per cent," Ojji says.

Health experts, however, affirm the safety of anticoagulants and advise that they should be administered exactly as intended for the recommended duration of time.

Additionally, health experts assert that DOAC therapies have improved management, dosing and compliance of anticoagulants.

For many patients, the benefits of taking an anticoagulant far outweigh the risk of bleeding, according to cardiologists, who note that even when bleeding occurs as a side effect, it can be managed and will rarely be life-threatening.

Analysts believe that anticoagulation therapy remains the cornerstone of management of patients at risk of VTE and AFib, and should be initiated without delay to forestall complications and death.