Less benefit from warfarin in diabetics after myocardial infarction?
OBJECTIVE
To examine the impact of prognostic factors on the outcome of treatment with warfarin or aspirin after acute myocardial infarction.


METHODS
Patients from the Warfarin Aspirin Re-Infarction Study, assigned to treatment with warfarin (n = 1,216) or aspirin (n = 1,206) after myocardial infarction, were stratified according to important prognostic factors. Survival from the composite endpoint of death, myocardial infarction and thromboembolic stroke was estimated within each stratum by odds ratios (OR). The effect of therapy was then tested for heterogeneity across the two groups. Unadjusted analyses were complemented with regression analyses.


RESULTS
In diabetics the OR was 1.54 (95% CI 0.80-2.94) compared to 0.75 (95% CI 0.60-0.93) in nondiabetic patients. The latter difference was statistically significant when testing for heterogeneity, suggesting effect modification of warfarin by diabetes. After adjusting for confounders, diabetic patients who received warfarin had a 56% excess risk of an endpoint as compared with those receiving aspirin. By contrast, nondiabetic patients on warfarin had a 22% lower risk of an endpoint than those allocated to aspirin.


CONCLUSIONS
The present data suggest less benefit from warfarin as compared to aspirin in diabetics. The mechanisms behind this remain in question.
Smith
Pål J
PJ
Department of Internal Medicine, Asker and Baerum Hospital, Rud, Norway.
Hurlen
Mette
M
Abdelnoor
Michael
M
Arnesen
Harald
H
D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage* / Q000009:adverse effects; D001241:Aspirin / Q000008:administration & dosage* / Q000009:adverse effects; D015986:Confounding Factors, Epidemiologic; D048909:Diabetes Complications / Q000188:drug therapy* / Q000401:mortality / Q000517:prevention & control; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000188:drug therapy* / Q000401:mortality / Q000517:prevention & control; D016017:Odds Ratio; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage* / Q000009:adverse effects; D011379:Prognosis; D016016:Proportional Hazards Models; D012307:Risk Factors; D020521:Stroke / Q000150:complications / Q000401:mortality / Q000517:prevention & control; D016019:Survival Analysis; D013923:Thromboembolism / Q000150:complications / Q000401:mortality / Q000517:prevention & control; D016896:Treatment Outcome; D014859:Warfarin / Q000008:administration & dosage* / Q000009:adverse effects
D000925:Anticoagulants; D010975:Platelet Aggregation Inhibitors; D014859:Warfarin; D001241:Aspirin