Abstract
Frequent prothrombin time (PT) and international normalized ratio (INR) testing is critical for millions of people on lifelong anticoagulation with warfarin. Currently, testing is performed in hospital laboratories or with expensive point-of-care devices limiting the ability to test frequently and affordably. We report a proof-of-concept PT/INR testing system that uses the vibration motor and camera on smartphones to track micro-mechanical movements of a copper particle. The smartphone system computed the PT/INR with inter-class correlation coefficients of 0.963 and 0.966, compared to a clinical-grade coagulation analyzer for 140 plasma samples and demonstrated similar results for 80 whole blood samples using a single drop of blood (10 μl). When tested with 79 blood samples with coagulopathic conditions, the smartphone system demonstrated a correlation of 0.974 for both PT/INR. Given the ubiquity of smartphones in the global setting, this proof-of-concept technology may provide affordable and effective PT and INR testing in low-resource environments.
Highlights
Frequent prothrombin time (PT) and international normalized ratio (INR) testing is critical for millions of people on lifelong anticoagulation with warfarin
Medication effects must be closely monitored via frequent prothrombin time (PT) or international normalized ratio (INR) tests to assess coagulation properties due to the drug’s narrow therapeutic index and interactions with food and other medications[4]
While newer anticoagulants that do not rely on regular PT/INR testing are increasing in popularity, studies show that warfarin remains the most commonly prescribed outpatient blood thinner[5]
Summary
Frequent prothrombin time (PT) and international normalized ratio (INR) testing is critical for millions of people on lifelong anticoagulation with warfarin. For millions of people, medical conditions such as atrial fibrillation, mechanical heart valves and genetic mutations increase the risk of morbidity and mortality from blood clotting[2]. These individuals require lifelong administration of anticoagulation drugs such as warfarin, an effective medication and one of the most common causes of hospitalization due to adverse drug events[3]. PT/INR testing monitors extrinsic and common pathways of the coagulation cascade These tests are usually performed in a laboratory on expensive equipment after separating plasma from whole blood. Repurposing these smartphone sensors for PT/ INR testing could enable a more affordable blood clot testing tool
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