Editing Prothrombin time (section)

==Near-patient testing==
In addition to the laboratory method outlined above, near-patient testing (NPT) or home INR monitoring is becoming increasingly common in some countries. In the United Kingdom, for example, near-patient testing is used both by patients at home and by some anticoagulation clinics (often hospital-based) as a fast and convenient alternative to the lab method. After a period of doubt about the accuracy of NPT results, a new generation of machines and reagents seems to be gaining acceptance for its ability to deliver results close in accuracy to those of the lab.<ref>{{cite journal  |vauthors=Poller L, Keown M, Chauhan N, etal |title=European Concerted Action on Anticoagulation. Correction of displayed international normalized ratio on two point-of-care test whole-blood prothrombin time monitors (CoaguChek Mini and TAS PT-NC) by independent international sensitivity index calibration |journal=Br. J. Haematol. |volume=122 |issue=6 |pages=944–9 |date=September 2003 |pmid=12956765 |doi=10.1046/j.1365-2141.2003.04521.x|doi-access=free }}</ref>

[[File:Patient testing with microINR from iLine Microsystems.jpg|thumb|Patient testing with microINR from iLine Microsystems]]
[[File:CoaguChekXS with SoftClix and test strip.png|thumb|150px|A Roche CoaguChek XS]]

In a typical NPT set up, a small table-top device is used. A drop of capillary blood is obtained with an automated finger-prick, which is almost painless. This drop is placed on a disposable test strip with which the machine has been prepared. The resulting INR comes up on the display a few seconds later. A similar form of testing is used by people with [[diabetes mellitus|diabetes]] for monitoring [[blood sugar]] levels, which is easily taught and routinely practiced.{{citation needed|date=November 2021}}

Local policy determines whether the patient or a coagulation specialist (pharmacist, nurse, general practitioner or hospital doctor) interprets the result and determines the dose of medication. In Germany and Austria, patients may adjust the medication dose themselves,{{Citation needed|date=February 2007}} while in the UK and the US this remains in the hands of a health care professional.

A significant advantage of home testing is the evidence that patient self-testing with medical support and patient self-management (where patients adjust their own anticoagulant dose) improves anticoagulant control. A meta analysis which reviewed 14 trials showed that home testing led to a reduced incidence of complications (bleeding and thrombosis) and improved the time in the therapeutic range, which is an indirect measure of anticoagulant control.<ref>{{cite journal |vauthors=Heneghan C, Alonso-Coello P, Garcia-Alamino JM, Perera R, Meats E, Glasziou P |s2cid=1494933 |title=Self-monitoring of oral anticoagulation: a systematic review and meta-analysis |journal=Lancet |volume=367 |issue=9508 |pages=404–11 |date=February 2006 |pmid=16458764 |doi=10.1016/S0140-6736(06)68139-7}}</ref> In 2022, a smartphone system was introduced by researchers to perform PT/INR testing in an inexpensive and accessible manner.<ref>{{Cite journal |last1=Chan |first1=Justin |last2=Michaelsen |first2=Kelly |last3=Estergreen |first3=Joanne K. |last4=Sabath |first4=Daniel E. |last5=Gollakota |first5=Shyamnath |date=2022-02-11 |title=Micro-mechanical blood clot testing using smartphones |journal=Nature Communications |language=en |volume=13 |issue=1 |pages=831 |doi=10.1038/s41467-022-28499-y |pmid=35149711 |pmc=8837659 |bibcode=2022NatCo..13..831C |issn=2041-1723}}</ref> It uses the vibration motor and camera ubiquitous on smartphones to track micro-mechanical movements of a copper particle and compute PT/INR values.

Other advantages of the NPT approach are that it is fast and convenient, usually less painful, and offers, in home use, the ability for patients to measure their own INRs when required. Among its problems are that quite a steady hand is needed to deliver the blood to the exact spot, that some patients find the finger-pricking difficult, and that the cost of the test strips must also be taken into account. In the UK these are available on prescription so that elderly and unwaged people will not pay for them and others will pay only a standard prescription charge, which at the moment represents only about 20% of the retail price of the strips. In the US, NPT in the home is currently reimbursed by [[Medicare (United States)|Medicare]] for patients with mechanical heart valves, while private insurers may cover for other indications. Medicare is now covering home testing for patients with chronic atrial fibrillation. Home testing requires a doctor's prescription and that the meter and supplies are obtained from a Medicare-approved Independent Diagnostic Testing Facility (IDTF).{{citation needed|date=June 2015}}

There is some evidence to suggest that NPT may be less accurate for certain patients, for example those who have the [[lupus anticoagulant]].<ref name="pmid9245222">{{cite journal |author1=Moll, S  |author2=Ortel, TL. |s2cid=53090686 |title=Metering Warfarin Therapy in Patients with Lupus Anticoagulants. |journal=Annals of Internal Medicine |volume=127 |issue=3 |pages=177–185 |date=August 1997 |pmid=9245222 |doi=10.7326/0003-4819-127-3-199708010-00001}}</ref>

===Guidelines===
International guidelines were published in 2005 to govern home monitoring of oral anticoagulation by the International Self-Monitoring Association for Oral Anticoagulation.<ref>{{cite journal| title=Guidelines for implementation of patient self-testing and patient self-management of oral anticoagulation. International consensus guidelines prepared by International Self-Monitoring Association for Oral Anticoagulation| author=Jack Ansell| journal=International Journal of Cardiology| date=10 March 2005| doi=10.1016/j.ijcard.2003.11.008| pmid=15721497| volume=99| issue=1| pages=37–45}}</ref> The international guidelines study stated, "The consensus agrees that patient self-testing and patient self-management are effective methods of monitoring oral anticoagulation therapy, providing outcomes at least as good as, and possibly better than, those achieved with an anticoagulation clinic. All patients must be appropriately selected and trained. Currently, available self-testing/self-management devices give INR results which are comparable with those obtained in laboratory testing."

Medicare coverage for home testing of INR has been expanded in order to allow more people access to home testing of INR in the US. The release on 19 March 2008 said, "[t]he Centers for Medicare & Medicaid Services (CMS) expanded Medicare coverage for home blood testing of prothrombin time (PT) International Normalized Ratio (INR) to include beneficiaries who are using the drug warfarin, an anticoagulant (blood thinner) medication, for chronic atrial fibrillation or venous thromboembolism." In addition, "those Medicare beneficiaries and their physicians managing conditions related to chronic atrial fibrillation or venous thromboembolism will benefit greatly through the use of the home test."<ref>{{cite web | title= Medicare expands coverage for home blood testing of prothrombin time international normalized ratio| publisher= The [[Centers for Medicare and Medicaid Services]] | date= 19 March 2008| url= https://www.cms.hhs.gov/apps/media/press/release.asp?Counter=2987 }}</ref>