In patients taking oral anticoagulants, 44% of hemorrhages occurred when INRs were above the therapeutic range, and 48% of thromboemboli occurred when INRs were below the therapeutic range.
Meta-Analysis (n=71,065)
Does improved anticoagulation control prevent hemorrhagic and thromboembolic events in patients taking oral anticoagulants?
Almost half of all anticoagulant-associated adverse events (hemorrhages and thromboemboli) occur when INRs are outside the therapeutic range, highlighting the critical need for improved anticoagulation control.
BACKGROUND: Patients taking anticoagulants orally over the long term have international normalized ratios (INRs) outside the individual therapeutic range more than one-third of the time. Improved anticoagulation control will reduce hemorrhagic and thromboembolic event rates. To gauge the potential effect of improved anticoagulation control, we undertook to determine the proportion of anticoagulant-associated events that occur when INRs are outside the therapeutic range. METHODS: We conducted a meta-analysis of all studies that assigned hemorrhagic and thromboembolic events in patients taking anticoagulants to discrete INR ranges. We identified studies using the MEDLINE (1966-2006) and EMBASE (1980-2006) databases. We included studies reported in English if the majority of patients taking oral anticoagulants had an INR range with a lower limit between 1.8 and 2 and an upper limit between 3 and 3.5, and their INR at the time of the hemorrhagic or thromboembolic event was recorded. RESULTS: The final analysis included results from 45 studies (23 that reported both hemorrhages and thromboemboli; 14 that reported hemorrhages only; and 8, thromboemboli only) involving a median of 208 patients (limits of interquartile range 25th-75th percentile 131-523 subjects; total n = 71 065). Of these studies, 64% were conducted at community practices; the remainder, at anticoagulation clinics. About 69% of the studies were classed as having moderate or high quality. Overall, 44% (95% confidence interval CI 39%-49%) of hemorrhages occurred when INRs were above the therapeutic range, and 48% (95% CI 41%-55%) of thromboemboli took place when below it. The mean proportion of events that occurred while the patient's INR was outside the therapeutic range was greater for studies with a short mean follow-up (< 1 yr). Between-study heterogeneity was significant (p < 0.001). INTERPRETATION: Improved anticoagulation control could decrease the likelihood of almost half of all anticoagulant-associated adverse events.
Oake et al. (Tue,) conducted a meta-analysis in Patients taking oral anticoagulants (n=71,065). Oral anticoagulants was evaluated on Proportion of hemorrhages occurring above therapeutic INR range (95% CI 39%-49%). In patients taking oral anticoagulants, 44% of hemorrhages occurred when INRs were above the therapeutic range, and 48% of thromboemboli occurred when INRs were below the therapeutic range.