Medicosnext
An international normalized ratio (INR) test is critical for all people who are receiving warfarin treatment. Warfarin, a vitamin K antagonist, is one of the most widely prescribed anticoagulants. But it is difficult to manage, as it has both a narrow therapeutic index and numerous drug and dietary interactions. “Its multiple interference with food, temperature, water, geographical location, disease states, and almost all kinds of medicines could cause great harm if not monitored and dosed correctly,” says Dr. Raamesh Koirala, a cardiac surgeon at Sahid Gangalal National Heart Centre.
The INR is a numeric value calculated from the prothrombin time (PT), a clotting assay result, and the International Sensitivity Index (ISI), which indicates sensitivity of the reagent used to perform the assay. One of the major challenges with warfarin is maintaining the patient’s INR within the predetermined therapeutic range. It can neither be too high nor too low. Therefore, regular INR monitoring is a must to safeguard patients on anticoagulation therapy. “Many fatalities may occur if they don’t check their INR. There is an increased risk of bleeding if the INR is too high, and there is a risk of blood clotting if it’s too low. The high doses can make people bleed from head, stomach, while brushing, coughing, and in cases of women, menstruation will not stop.”
Warfarin will slow down the process of blood clotting. “But, as it is made from plant extracts, there are many vegetables like cabbage, kale, broccoli, spinach, and lettuce that we eat daily that will slow down the effect of warfarin. Therefore, eating a lot of food rich in vitamin K can lower the PT and INR, making warfarin less effective and potentially increasing the risk of blood clots,” says Dr. Koirala.
“Its effect is so rampant. It’s really difficult to say what not to eat to patients. We usually tell them to eat what they normally do. To eat a consistent and balance diet and keep doing their INR test,” the doctor adds. “The test is so sensitive, and it is difficult to get an accurate result from the labs and reagents, so a lot of people have died due to this.” Therefore, frequent INR monitoring is the only way to maintain a balance between preventing clots and avoiding the risks of bleeding.
There are two classes of antithrombotic drugs: anticoagulants and antiplatelet drugs. Both work to prevent clots in blood vessels but affect different blood clotting processes. Anticoagulants slow down clotting, thereby reducing fibrin formation and preventing clots from forming and growing in your heart, veins, or arteries, while antiplatelet agents prevent platelets from clumping and also prevent clots from forming and growing.
Can PT/INR confirm that one is 100 % risk free?
• An INR of 1 is normal and is found in people who are not on warfarin.
• An INR of 2 means that your blood takes twice as long to clot than a normal person. It doesn’t guarantee that it won’t clot. It may clot, but the risk is low.
• An INR of 3 means that your blood takes three times as long to clot as a normal person.
There are two classes of antithrombotic drugs: anticoagulants and antiplatelet drugs. Both work to prevent clots in blood vessels but affect different blood clotting processes.
The optimal INR target range is 2.0-3.0, but it depends on the indications for anticoagulation. “Though we follow the guidelines of American College of Cardiology/American Heart Association, we have a tendency to be satisfied with a bit low INR value,” says Dr. Koirala.
• For micro valves or mechanical heart valves: our target INR range is 2.5-3.5
• For aortic valves: our target INR range is 2-3
• For atrial fibrillation: our target INR range is 2-2.5 or 2-3
Warfarin dose adjustment
If a person’s INR is within a desired range, a patient has to check his or her INR every three to four weeks. If the report is not within the desired range, he or she needs to readjust the dose of drug to keep the INR readings as close to the target as possible. For that, they need to either check their INR every day, or get admitted to the hospital, informs Dr. Koirala.
According to Dr. Koirala, people with atrial fibrillation (AF) are those in most need of warfarin. But, in Nepal, the maximum number of people receiving warfarin are those with mechanical valves. “It is not possible to give warfarin to people with AF, because the number is too big. Also, the chances of blood clotting are low for AF, while people with mechanical valves are at highest risk for clotting. So, they are in need of warfarin the most.”
Our Effort
Our Effort is a non-profit organization running under the direct support of Dr. Raamesh Raj Koirala and Dr. Anil Acharya to help people requiring constant monitoring of INR managed anticoagulant therapy.
Founded on Kartik 13, 2068, Our Effort is currently running the PT/INR mobile clinic with over 2000 beneficiaries directly. It is registered in Jhapa district and is financed by Dr. Raamesh Raj Koirala and supported by Dr. Anil Acharya and other doctors, while some fund is generated from French donors who want to help the needy patients. “Some of my friends in France were sponsoring valves to 12-13 needy patients at the Sahid Gangalal National Heart Centre(SGNHC) annually for many years.When they asked me for a way to support the poor patients in the hospital, I gave them the names and they paid for their surgeries,” says Dr. Koirala.
“Later, when the government decided to give free valves to those who couldn’t afford it, we thought of a way to make best use of the fund. So, I proposed to them to invest some money to buy INR test machines for people residing outside the valley. So, with their support and some of my investment Our Effort’got started.
It was founded with the desire to help people outside the valley do the INR test without having to travel to Kathmandu. “Before, we asked the patients to come to Kathmandu every three months to do the INR test.”
According to Dr. Koirala, out of 600-700 valve operations in SGNHC every year, around 300 people are enrolled in this program. Our Effort provides warfarin to 95 percent of patients with mechanical valves. The remaining 5 percent are people with tissue valve and AF, he adds.
The organization charges nominal fee from patients who purchase the strips for the test and for the medicines that they receive. There are four people involved in field activity of the clinic, along with four people in the technical department making all the necessary arrangements for the smooth operation of the clinic.
Currently, the entire focus of Our Effort has been in anticoagulant therapy service through the PT/INR mobile clinic. Its main concern is to provide convenient and easily available service to patients. There are currently 14 stations across the country.
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