Updated November 2020

*Please note that NATF does not provide or sell home INR machines. If you’re interested in at-home INR testing, please contact your healthcare provider or health insurance carrier for more information.*

Patients on warfarin need to get their INR levels measured regularly, which often involves visiting a local anticoagulation clinic, lab, or doctor’s office to get a blood test. However, there’s another option for INR testing: in-home testing, also known as self-testing or point-of-care testing.

“I think a lot of patients don’t think of home testing as an option because they don’t really know about it,” explained Dr. Peter Collins, an Advanced Clinical Practice Pharmacist at Brigham and Women’s Hospital (BWH). Dr. Collins works in the anticoagulation clinic at BWH and helps patients on warfarin get set up with in-home INR testing.

“Doctors’ offices, and even sometimes the anticoagulation clinics, don’t necessarily present in-home testing as an option,” he continued, acknowledging that there’s no specific reason for why in-home testing isn’t advertised more frequently to patients. “I think education would definitely make more patients aware.”

A PT/INR monitoring system

What benefits come with in-home testing?

  • In-home testing is convenient. It allows patients to test their INR levels without the need for frequent visits to a lab.
  • In-home testing only requires a finger stick, instead of a full blood sample.
  • In-home testing may lead to fewer blood clots.

Self-testing patients typically check their levels more often than patients who go to the lab, so they’re more likely to have their warfarin dosage adjusted as needed to stay in the correct INR range. Dr. Collins also noted that this increase in time within therapeutic range may also be influenced by the types of patients who seek out in-home testing. “These patients are often highly motivated and invested in their healthcare, which leads to strict adherence to their treatment plans,” he explains.

Who’s a good candidate for in-home testing?

In-home testing is a good option for patients who can’t make it to the lab frequently, who travel often, who have difficulty leaving their homes, or who want to be more independent. Whatever your reason for switching to home testing, the key is that you remain committed to testing your levels.

“When a patient shows interest in in-home testing, we look at the indication for their anticoagulation. There are some blood disorders that interfere with how the machine measures the INR ratings,” he explained, citing antiphospholipid syndrome (APLS) as an example. “For those patients, we would want to avoid point-of-care testing.”

How do I get started with home INR testing?

If you’re interested in in-home testing, you must speak to the provider who manages your warfarin. They will work with you to decide if you’re a good fit for in-home testing. If you are, they’ll submit a form to a medical service company with your information. There are several companies that provide the machines and patient training, including Acelis, Roche, and RCS.

“Once you’re determined to be a good candidate for self-testing, your provider or pharmacy team will go through a company that handles training and INR test results,” explained Dr. Collins. “Typically, these companies send a trainer out to your home to review how to use the machine correctly and help you report the results for the first time.” Trainings can also be done virtually. In the midst of the COVID-19 pandemic, all trainings have shifted to a virtual platform.

“The testing machines themselves only have two buttons and are pretty easy to use. Patients who have diabetes will be familiar with this type of machine – it follows the same process as testing blood sugar. The most important thing is to make sure that you get enough blood on the test strip,” says Dr. Collins.

After testing your blood, you’ll have to report the results to the company you’re working with. Most patients use an app or a website to send in their reports. Once the company gets the result, they’ll send it to your provider. The company will also manage billing and the insurance-related parts of the process. When your provider receives your results, they can make dosage adjustments as needed.

There are several other important points to note before you transition to home testing:

  • You’ll usually need to have your INR tested at a lab or clinic a few times before switching to home testing. Before you start testing your levels on your own, your healthcare provider will need to make sure that your warfarin dose is stable. Most insurance plans require patients to be on warfarin and get lab tests for 3 months before switching to home testing. (Some plans have waived this requirement during COVID-19.)
  • Insurance coverage for home testing varies from plan to plan. Many insurers cover the cost of home testing, but some patients may have a copay or some out-of-pocket expense.
  • Most insurers also require that you test your levels at least every 2 weeks, and some plans require weekly tests. So, if you’ve typically had a blood draw once a month or every 6 weeks, you might have to test yourself 2-3 times more frequently – but the tradeoff is that you can do it at home. The companies that provide the machines/training will remind you to submit your report if they don’t hear from you within a couple of weeks.

Are there any challenges to in-home testing?

In-home testing is not for everyone, and it does come with challenges. One major issue is that the in-home testing machines can be less accurate than testing at a clinic. Dr. Collins has found that some machines can be up to 20-30% off in measuring INR levels. “It’s not as accurate as a hospital blood draw, but we have additional tools to ensure we’re getting the most accurate result,” said Dr. Collins.  “We have policies in place to help with that.” Patients who self-test must also understand that they may have to return to the clinic for testing if their INR levels are found to be high. 

As with all forms of treatment and testing, INR in-home testing has benefits and challenges. It’s not the appropriate testing method for every patient. Talk to your healthcare provider if you’re interested in pursuing in-home testing.