Warfarin (brand name Coumadin) is often referred to as a 'blood thinner'. It works to prevent blood clots in the body. By preventing the formation of clots, it lessens the risk for stroke (caused by a blood clot in the brain) and pulmonary embolism ('PE' or a blood clot in the lungs) in many patients with certain conditions.

Warfarin is dosed according to the results of a blood test called an INR. Measuring an INR while you are taking warfarin tells the doctor how fast your blood is clotting and if your dose of warfarin needs to be increased or decreased. A typical INR range for most people taking warfarin is 2 to 3. Some people with mechanical heart valves will have an INR goal of 2.5 to 3.5. The dose of warfarin is different for everyone. In other words, some people will only need 2 mg daily to get their INR in the right range. Others will need 10mg daily to get to their INR range. In the beginning, your INR should be measured at least weekly, and many times more often, until you are within the correct INR range. Then, your INR may be monitored less frequently.

Personally, I can't tell you how many times I've seen a doctor in the hospital prescribe a patient 'warfarin 5mg daily' at discharge and instruct the patient to follow up with their Primary Care Doctor in 2 weeks. When first being discharged, many patients aren't yet stable on a dose and for some patients, two weeks is too long. Warfarin is a medication that needs to be monitored closely. One patient may need 5 or10mg daily. Others may only need 1mg daily. If a person that needs only 1mg daily receives 5mg daily, that person could experience excessive bruising, bleeding, or death. Many physicians don't have the time to follow up with warfarin  patients as often as they need to. This puts the patient at risk for serious side effects. For this reason, anticoagulation clinics or 'Coumadin clinics' have popped up all over the U.S. These clinics are usually run by pharmacists. The sole purpose of these clinics is to see  patients to monitor and adjust their warfarin therapy. They help free up the physician while helping the patient get the most out of their warfarin therapy. The services provided by these clinics are covered by Medicare and by most insurance programs.

If you were to go to one of these clinics, you could expect to be seen by a pharmacist in a private consultation room. Here you will likely be asked questions about your current regimen, other medications you are taking, foods you are eating and physical activity, as all of these items tend to affect your INR. Then the pharmacist would collect a small blood sample by pricking your finger. This blood sample is fed into a machine that is able to give you an INR reading in under a minute. Based on this INR reading, the pharmacist will adjust your warfarin dosing and set up a follow-up appointment for you. Patients can be seen as often as needed in order to get their INR in the therapeutic range. This process is very efficient and allows the warfarin therapy to be tailored to the patient.

Many studies have looked at these new pharmacist-based clinics to see how they stack up against physician-monitored warfarin. These studies have found that overall control of the INR was better in patients who were seen at pharmacist-run clinics. These studies also found that the incidents of side effects like bleeding were less frequent when the patient was seen at a pharmacist-run clinic. ^1-4 There was one trial that did not find a difference between the two different monitoring methods.⁵ However, not all providers at this clinic were pharmacists and the study itself was also poorly conducted.

In addition to frequently showing better INR results, these studies also showed that pharmacist-based clinics were more likely to reduce the cost of healthcare. This is because properly managed warfarin therapy can reduce hospitalizations and emergency department visits. One study found that a pharmacist-managed clinic saved over $162,000 per 100 patients per year in health care costs.¹ Another clinic that had expanded its service to include other anti-clotting therapies showed a savings of $1,108,587 in 391 patients.²

Having worked at one of these clinics, I can tell you that the services they provide can be invaluable. When a patient uses one of these clinics, the doctor and patient can rest assured that the patient is getting the most of their warfarin therapy. If you are beginning warfarin therapy, or have been on it for some time but have had problems with side effects or staying in you INR range, you may want to talk to your doctor about a referral to one of these clinics.

Author: Christi Larson, Pharm. D.

Dr. Larson is a Clinical Infusion Pharmacist, author of Empowered Medicine; A Guide for Consumers and creator of www.empoweredmedicine.com. You can read more about her by visiting www.EmpoweredMedicine.com and clicking on the 'About Us' tab.  EmpoweredMedicine.com is committed to providing evidence-based medical information.

REFERENCES:

1. Chiquette E, Amato MG, Bussey HI. Comparison of an anticoagulation clinic with usual medical care: anticoagulation control, patient outcomes, and health care costs. Arch Intern Med 1998;158:1641-7.
2. Tillman DJ, Charland SL, Witt DM. Effectiveness and economic impact associated with a program for outpatient management of acute deep vein thrombosis in a group model health maintenance organization. Arch Intern Med 2000;160:2926-32.
3. Amruso NA. Ability of clinical pharmacists in a community pharmacy setting to manage anticoagulation therapy. J Am Pharm Assoc 2004;44:467-71.
4. Ernst ME, Brandt KB. Evaluation of 4 years of clinical pharmacist anticoagulation case management in a rural, private physician office. J Am Pharm Assoc 2003;43:630-6 
5. Matchar DM, Samsa GP, Cohen SJ, et al. Improving the quality of anticoagulation of patients with atrial fibrillation in managed care organizations: results of the managing anticoagulation services trial. Am J Med 2002;113:42-51.