Comparison of outcomes among patients randomized to warfarin therapy according to anticoagulant control: results from SPORTIF III and V.
BACKGROUND
Warfarin sodium reduces stroke risk in patients with atrial fibrillation, but international normalized ratio (INR) monitoring is required. Target INRs are frequently not achieved, and the risk of death, bleeding, myocardial infarction (MI), and stroke or systemic embolism event (SEE) may be related to INR control.


METHODS
We analyzed the relationship between INR control and the rates of death, bleeding, MI, and stroke or SEE among 3587 patients with atrial fibrillation randomized to receive warfarin treatment in the SPORTIF (Stroke Prevention Using an Oral Thrombin Inhibitor in Atrial Fibrillation) III and V trials. The mean+/-SD follow-up was 16.6 +/- 6.3 months. Patients were divided into 3 equal groups (those with good control [>75%], those with moderate control [60%-75%], or those with poor control [<60%]) according to the percentage time with an INR of 2.0 to 3.0. Outcomes were compared according to INR control. The main outcome measures were death, bleeding, MI, and stroke or SEE.


RESULTS
The poor control group had higher rates of annual mortality (4.20%) and major bleeding (3.85%) compared with the moderate control group (1.84% and 1.96%, respectively) and the good control group (1.69% and 1.58%, respectively) (P<.01 for all). Compared with the good control group, the poor control group had higher rates of MI (1.38% vs 0.62%, P = .04) and of stroke or SEE (2.10% vs 1.07%, P = .02).


CONCLUSIONS
In patients with atrial fibrillation taking warfarin, the risks of death, MI, major bleeding, and stroke or SEE are related to INR control. Good INR control is important to improve patient outcomes.
White
Harvey D
HD
Green Lane Cardiovascular Service, Auckland City Hospital, Auckland 1030, New Zealand. harveyw@adhb.govt.nz
Gruber
Michael
M
Feyzi
Jan
J
Kaatz
Scott
S
Tse
Hung-Fat
HF
Husted
Steen
S
Albers
Gregory W
GW
D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage*; D001281:Atrial Fibrillation / Q000188:drug therapy / Q000401:mortality*; D004617:Embolism / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D006470:Hemorrhage / Q000453:epidemiology; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology*; D020521:Stroke / Q000453:epidemiology*; D015996:Survival Rate; D016896:Treatment Outcome; D014859:Warfarin / Q000008:administration & dosage*
D000925:Anticoagulants; D014859:Warfarin