INR Finger Stick Machines

If you participate on our Facebook page then you probably already know the stand that the APSFA takes regarding finger stick machines for testing APS patients’ INRs—finger stick machines are not accurate for APS patients.

Unfortunately, over half of the APSFA board of directors have had experience with erroneous INR readings from a finger stick machine. Luckily, the errors did not result in anything serious, but when the numbers are off it can be the difference between holding a dose of a blood thinner or having a stroke.

This is not a risk we are willing to take and not a risk we want other APS patients to take without being educated. This information has been on our links page for some time, but we decided it was time to take a formal stance.

We have been approached by vendors offering us advertising bids for thousands of dollars. We have turn them down. It is against our ethical standards to promote something that could harm or even kill you. You are worth more to us than that money. There are more ethical ways to raise money for our mission. Your safety will always come first in our eyes.

On this page is a compilation of articles, brochures, and links from many different sources on APS patients and INR (finger stick) machines. If nothing else, please educate yourself and call the manufacture to ask them point blank if they are accurate for APS patients. Thank you.

Just Say NoINR Machine Facts for APS Patients

Devices for ambulatory and home monitoring of blood pressure, lipids, coagulation, and weight management, part 2
Am J Health Syst Pharm.2005; 62: 1894-1903. Kelly L. Scolaro, Pamela L. Stamm and Kimberly Braxton Lloyd Copyright © 2005 by the American Society of Health-System Pharmacists.


INR Self Testing
INRs from POC instruments are unreliable in about 1/3rd of patients with the clotting disorder called antiphospholipid syndrome (APLA syndrome) who are on warfarin. In these patients, the POC devices give INR readings that are too high, or the instruments report error messages. This is the case with any of the 3 instruments on the market. If you have APLA syndrome, your INRs should be checked from blood drawn from a vein and tested in a laboratory.


Patient Variables in PT/INR Testing with INRatio
Technical Bulletin from HemoSense makers of INRatio. Clearly states that APS effects its results. The APSFA does not promote, sell or make money from this company nor the vendors that sell them. However, if this document has been relocated again, please feel free to contact us for it.


My Experience with Finger Stick (Home) INR Machines
Patient’s story on her use of a Home INR Machine and supporting company information.


MAUDE Adverse Event Report
Discrepant results (accuracy) comparison of inratio test with lab results provided by end-user at time complaint was filed: date: early 2007, inratio: 2. 1, lab: 8. 5, mean: 5. 3, confidence limits: unable to be determined. Per internal procedure, the mean of the inratio meter and comparative system inr were calculated. The confidence limits cannot be determined. The readings are considered inaccurate based on “area outside the acceptance region” table. The results are considered discrepant within the context of the documented variability for inr testing. Therefore, further testing is required at this time. In troubleshooting found that the pt has antiphospholipid syndrome. It was explained that possible interferences may be due to the varying levels of the antibodies. Pts condition may cause the discrepant errors.


Antiphospholipid Syndrome (APS) – NO to Home INR Machines!!
I started this blog to help get the word out that Home INR machines are NOT safe to use for patients with Antiphospholipid Syndrome. If you have APS, please read! Thanks!


INRatio Monitor and Interfering Substances
Anti-phospholipid antibodies can disrupt the phospholipid in the PT reagent that is necessary for the clotting reaction to occur thus artificially elevating the INR. The APSFA does not promote, sell or make money from this company nor the vendors that sell them. However, if this document has been relocated again, please feel free to contact us for it.


Thoratec Receives FDA Warning Letter, Plans Recall (ProTime)
Thoratec’s International Technidyne Corp. (ITC) division has received an FDA warning letter citing concerns about its quality systems, specifically those related to certain lots of its ProTime System anticoagulation monitoring device…..of incorrect readings of patient blood coagulation levels.


CoaguChek XS System – Patient Experience
Registration Required to read story. “I called Roche and expressed my concerns about the reliability of the machine. They told me that at higher INRs (above 4.0) the machine becomes less reliable. They also told me that the machine doesn’t work very well for people with Antiphospholipid Antibodies because these same antibodies are on the test strips! She said that especially when someone with APS is having a flare up the machine may not work well due to the high level of antibodies in the blood.”


i-STAT® PT/INR test
The i-STAT® PT/INR test is a whole blood determination of the prothrombin time used for monitoring oral anticoagulant (warfarin) therapy. The test determines the time required for complete activation of the extrinsic pathway of the coagulation cascade when initiated (activated) with a thromboplastin. Those using this machine should be getting vein draw comparisons at least every 6-8 weeks.


ProTime Systems
Representatives clearly state that this machine has problems with APS patients and patients with the Lupus Anticoagulant. Waiver for patients with APS must be signed. Those using this machine should be getting vein draw comparisons at least every 6-8 weeks. The APSFA does not promote, sell or make money from this company nor the vendors that sell them.


MAUDE Adverse Event Report
Discrepant results (accuracy) comparison of inratio test with lab results provided by end-user at time complaint was filed: date: 01/05/07, inratio: 6. 1, lab: 3. 8, mean: 4. 95, confidence limits: 2. 8-7. 2. Date: 01/15/07, inratio: 4. 3, lab: 2. 8, mean: 3. 55, confidence limits: 2. 2-5. 3. Per internal procedure, the mean of the inratio meter and comparative system inr were calculated. Both inratio and lab values are within the confidence limits for inr testing. The results are not considered discrepant within the context of the documented variability for inr testing. Therefore, further testing is not required at this time. Per text “pt has antiphospholipid antibody syndrome, (cardiolipin-positive, lupus-negative). ” pt’s condition may be causing interference.


INRatio by Alere formerly Hemosense
Representatives & Literature clearly states that this machine has problems with APS patient and patients with the Lupus Anticoagulant. Please see: http://www.apsfa.org/docs/HemoSense%20TechBull108.pdf Those using this machine should be getting vein draw comparisons at least every 6-8 weeks. The APSFA does not promote, sell or make money from this company nor the vendors that sell them. However, if this document has been relocated again, please feel free to contact us for it.


Validity of Criteria Used to Evaluate Fingerstick Devices That Assess International Normalized Ratio
Medical Decision Making, Vol. 26, No. 3, 239-246 (2006). Conclusion. The unvalidated criteria used to predict warfarin dosing agreement between 2 INR measurements are associated with large error. Warfarin dosing decisions should be measured directly in such assessments.


MAUDE Adverse Event Report
Caller alleged discrepant results compared with the lab. Results as follows: date: 01/12/07, inratio: 6. 1, lab: 3. 6. Ts updated this case on 01/18/2007 and 01/19/2007. 01/17/07, first test inr = 7. 5(old strip). Second test inr = 5. 5(new strip). Date: 01/19/07, inratio: 6. 5, lab: 4. 0. Caller has antiphospholipid syndrome and recently had an episode of multi organ infection resulting in failure of adrenal glands.


*INR Monitoring in Patients with Antiphospholipid Antibodies with Finger Stick INR Machines.
by: Stephan Moll, MD. A superb way to monitor INRs (International Normalized Ratio) in patients on oral anticoagulants who do NOT have antiphospholipid antibodies (APLA) is though use of “point of care instruments”, where the INR is tested on blood from a finger stick. This method gives fast results and is used by many physicians’ offices and by some patients at home. However, in patients with APLA on oral anticoagulants these instruments may give inaccurate readings.


CoaguChek & CoaguChek S Strip Insert
Literature clearly states that this machine has problems with APS patient and patients with the Lupus Anticoagulant. This is for the CoaguChek & CoaguChekS. Please call technical support at 800-428-4674 for more information. Those using this machine should be getting vein draw comparisons at least every 6-8 weeks. The APSFA does not promote, sell or make money from this company nor the vendors that sell them.


CoaguChekXS Strip Insert
Literature clearly states that this machine has problems with APS patient and patients with the Lupus Anticoagulant. This is for the new CoaguChekXS. Please call technical support at 800-428-4674 for more information. Those using this machine should be getting vein draw comparisons at least every 6-8 weeks. The APSFA does not promote, sell or make money from this company nor the vendors that sell them.


Factors That Influence INR system Comparisons
List includes Antiphospholipid Antibodies. The APSFA does not promote, sell or make money from this company nor the vendors that sell them. However, if this document has been relocated again, please feel free to contact us for it.


Hemochron Jr. Package Insert
Literature clearly states that this machine has problems with APS patient and patients with the Lupus Anticoagulant. Those using this machine should be getting vein draw comparisons at least every 6-8 weeks. The APSFA does not promote, sell or make money from this company nor the vendors that sell them.


Point-of-care testing of the international normalized ratio in patients with antiphospholipid antibodies.
SL Perry, GP Samsa, and TL Ortel Thromb Haemost, December 1, 2005; 94(6): 1196-202. Antiphospholipid antibodies can influence the results of clotting tests in a subset of patients, which can be a major obstacle in monitoring warfarin.The aim was to determine if point-of-care testing of the International Normalized Ratio (INR) is influenced by antiphospholipid antibodies. Please note the manufacture of this machine helped fund this study.


ProTime Microcoagulation System Package Insert
Literature clearly states that this machine has problems with APS patient and patients with the Lupus Anticoagulant. Those using this machine should be getting vein draw comparisons at least every 6-8 weeks. The APSFA does not promote, sell or make money from this company nor the vendors that sell them.


Coagucheck accuracy?
A long discussion about non-APS patients have accuracy issues with their finger stick readings, some of which had complications due to those inaccurate readings.


Alere INRatio® PT/INR Test Strips Package Insert
Lupus or antiphospholipid syndrome (APS) may falsely prolong the INR value. Testing with an APS-insensitive laboratory method is recommended for these patients.


Patient Education Blog | Clot Connect has posted a new item, ‘INR Self-Testing’
INRs from POC instruments are unreliable patients with the clotting disorder called antiphospholipid syndrome (APLA syndrome) who are on warfarin [ref 7]. In these patients, the POC devices give INR readings that are too high, or the instruments report error messages. This is the case with any of the 3 instruments on the market. If you have APLA syndrome, your INRs should be checked from blood drawn from a vein and tested in a laboratory. That value can then be compared to the INR obtained with a POC instrument from a finger stick. Only if both values correlate well may it be acceptable for you to use the POC machine for self-testing.


Anti-phospholipid Syndrome and PT/INR
Based on the conclusions of the studies mentioned, different methods of measuring PT/INR behave differently with different APA patients. It is therefore very important to assess the individual patient together with the responsiveness of the PT/INR reagent/system to be used to monitor warfarin therapy (lab or POC). It is also important when performing a correlation study comparing one PT/INR system to another to consider whether any of the patients included in the study have Anti-phospholipid Syndrome. The presence of such samples in the population may affect the correlation.


59 patients impacted by blood test error at Indian Head Union Hospital
The error was discovered because of changes to the reagents ” a substance that is mixed with a patient’s blood to do the test. When the region couldn’t get reagent for some aging equipment, senior technologists started to call around to find out how much reagent the rural sites had on hand and the testing error was discovered. About five rural labs need machines replaced. “We’re going to be rethinking our equipment needs in the rural sites as a whole,” Ledingham said. “Whether each of those five individual machines are going to be replaced or perhaps some of them will be serviced from a central site ” it will really depends on the needs of the patients and the clinicians in those communities.”


Accuracy Concerns on Testing Device for Blood-Thinning Drug
Dr. Gary Goldstein, a Florida internist, knew something was wrong with a blood-testing device in his office when, all of a sudden, it began giving out odd results.


An Advanced MAUDE Search
It is just not APS Patients anymore with inaccurate readings.


FDA Examines Safety of INR Point-of-Care Tests
By Amy Orciari Herman; Edited by Susan Sadoughi, MD, and André Sofair, MD, MPH.
The FDA convened a panel of experts on Friday to examine the accuracy of point-of-care tests to measure international normalized ratio (INR) in patients taking warfarin, the Wall Street Journal reports.
The agency says such tests have performed poorly in thousands of patients since their approval, with potentially false readings linked to 18 deaths in 2014 and 2015.
Two such tests, INRatio and INRatio2, were withdrawn from the market in 2014 over concerns that they gave faulty readings. INRatio has recently received much attention over its use in the ROCKET AF trial, which led to approval of the anticoagulant rivaroxaban (Xarelto). Critics assert that in ROCKET AF, falsely low INR readings with INRatio would have prompted higher warfarin doses—resulting in higher bleeding risks with the drug and thus making rivaroxaban seem relatively safer. The researchers reanalyzed their data, however, and concluded that the test did not significantly affect the trial’s primary outcomes.


Inaccurate Results from INR Meters Prompt New Information from FDA
The U.S. Food and Drug Administration (FDA) has published new information on the agency’s website for people who take warfarin (a blood thinner) and use portable, battery-operated INR test meters to monitor their therapy. This update was prompted by reports that some INR test meters may have generated inaccurate results. The FDA regulates INR test meters and test strips, and the agency wants to make sure all people who use these home-testing devices, regardless of make or model, are using them safely.

Accepted Standard of Deviation by Roche Diagnostics

Letter from Roche Diagnotics Discussing Inaccuracies in Antiphospholipid Syndrome (APS) patients.

Example Side by Side Comparisons from a Roche Machine with an APS patient.

Our Mission

Founded in 2005, the APS Foundation of America, Inc. is dedicated to fostering and facilitating joint efforts in the areas of education, public awareness, research, and patient services for Antiphospholipid Syndrome (APS) in an effective and ethical manner.

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APS Foundation of America, Inc.
P. O. Box 801
LaCrosse, WI 54602-0801

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