Key result
INR monitoring of oral anticoagulants is linked to ~57% fewer bleeding complications versus PT ratio.
Why the study?
Does monitoring oral anticoagulant therapy with the International Normalized Ratio (INR) reduce bleeding and thromboembolic complications compared to the prothrombin time (PT) ratio in patients in an anticoagulation clinic?
Observational (n=650)
No
Does monitoring oral anticoagulant therapy with the International Normalized Ratio (INR) reduce bleeding and thromboembolic complications compared to the prothrombin time (PT) ratio in patients in an anticoagulation clinic?
Absolute Event Rate: 2.9% vs 6.7%
p-value: p=0.02
Monitoring oral anticoagulant therapy with the INR significantly reduces bleeding complications compared to the PT ratio without increasing thromboembolic events.
INR monitoring was associated with fewer bleeds in this cohort; leaves open whether to prefer it over PT ratio without randomized confirmation.
The objective of our study was to determine the rates of bleeding complications and thromboembolic events in patients receiving oral anticoagulant therapy monitored with the prothrombin time (PT) ratio versus therapy monitored with the International Normalized Ratio (INR) using a retrospective time-series study design. Over 650 patients enrolled in a large anticoagulation clinic were studied during two time periods corresponding to the use of the PT ratio versus the INR to guide anticoagulant therapy, with over 400 patient-years of follow-up for each time period. The rate of bleeding complications using the PT ratio to guide therapy was 6.7% (1.2% major, 5.5% minor) per patient-year, compared with 2.9% (0% major, 2.9% minor) using the INR (p = 0.02). The rate of thromboembolic complications was 1.0% using the PT ratio, compared with 0.2% using the INR (p = NS). Therapy monitored with the INR required 19.8 visits per year, compared with 20.7 visits per year using the PT ratio. We conclude that the INR should be used to monitor oral anticoagulant therapy in an effort to reduce bleeding complications while maintaining an acceptable rate of thromboembolic events.
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Andrews et al. (1995) conducted an observational in Patients receiving oral anticoagulant therapy (n=650). International Normalized Ratio (INR) monitoring vs. Prothrombin time (PT) ratio monitoring was evaluated on Rate of bleeding complications per patient-year (p=0.02). Monitoring oral anticoagulant therapy with the INR significantly reduced bleeding complications compared to the PT ratio (2.9% vs 6.7% per patient-year, p=0.02).
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