Key result
Noninvasive Thrombo-Monitor Index correlates strongly with laboratory INR in warfarin-treated patients.
Why the study?
Does the noninvasive Thrombo-Monitor device accurately correlate with laboratory INR and prothrombin time (PT) values in hospitalized elderly patients receiving anticoagulant or antiplatelet therapy?
Cross-Sectional (n=115)
No
Does the noninvasive Thrombo-Monitor device accurately correlate with laboratory INR and prothrombin time (PT) values in hospitalized elderly patients receiving anticoagulant or antiplatelet therapy?
The noninvasive Thrombo-Monitor device demonstrates a significant correlation with laboratory INR and PT values in elderly patients on warfarin, showing potential as a painless alternative to venipuncture for coagulation monitoring.
TMI correlated with INR/PT in warfarin patients; leaves open clinical utility as noninvasive alternative pending prospective validation.
The feasibility of the noninvasive assessment of blood 'coagulability' (the tendency to coagulate) has been tested by using a novel device, the Thrombo-Monitor. It monitors, by using the principles of near infra-red (NIR) dynamic light scattering, the tendency of blood to create clots. The Thrombo-Monitor observes the very initial changes of blood viscosity, which occurs due to the temporarily induced stasis of capillary blood of the finger. One hundred and fifteen patients aged >65 years (matched by age and sex) participated in the study. Patients were initially divided into four groups based on the patient's medical therapy. The study groups were: warfarin, enoxaparin, aspirin and/or clopidogrel, and a control group. The medications were given according to the patient's comorbidities (eg, atrial fibrillation [AF], status post pulmonary embolism [S/p PE], status post cerebrovascular accident [S/p CVA]). The Thrombo-Monitor Index (TMI) is a noninvasive index, derived on the basis of laboratory test results of international normalized ratio (INR) and prothrombin time (PT) values. For the group of patients who were treated only with warfarin, TMI was adjusted by using the jackknife statistical approach to create maximum correlation and linearity with INR and PT values that ranged from 1.1 to 5.0. For all warfarin patients (N = 35) the TMI was found to have a good correlation with INR and PT values (R(2) = 0.64, P < 0.00001); mean TMI = 1.86 (SD = 0.91); mean INR and PT = 2.3 (SD = 0.91). The calibration curve thus generated was used to calculate the TMI for all other groups: aspirin group, mean TMI = 1.3 (SD = 0.14, N = 23), corresponding approximately to INR and PT values of 1.036; enoxaparin group (N = 24), mean TMI = 1.34 (SD = 0.304), corresponding to mean INR and PT values of 1.07 (SD = 0.3); control group, INR and PT ≥ 1 (N = 32), mean TMI = 1.24 (SD = 0.32). R(2) of all control and warfarin patients (N = 67) was 0.55 (P < 0.00001). In summary, the newly introduced TMI index is significantly correlated with INR and PT values.
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Yaffa Lerman (2011) conducted a cross-sectional in Hospitalized elderly patients undergoing anticoagulation or anti-aggregation therapy (n=115). Noninvasive Thrombo-Monitor device (model ELFI-3) using near infrared dynamic light scattering vs. Routine laboratory INR and prothrombin time (PT) venous blood test (Sysmex Lab) and unmedicated control group was evaluated on Correlation between noninvasive Thrombo-Monitor Index (TMI) and laboratory INR and PT values in warfarin-treated patients (R2 = 0.64, p=<0.00001). The noninvasive Thrombo-Monitor Index correlated strongly with laboratory INR and PT values in elderly warfarin-treated patients (R2 = 0.64, P < 0.00001).
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