January 11, 1999Archives of Internal Medicine199 citations
Ver artículo completoA Randomized Trial Comparing 5-mg and 10-mg Warfarin Loading Doses
Resultado clave
A 5-mg warfarin loading dose was more effective than a 10-mg dose in achieving a therapeutic INR without overanticoagulation (66% vs 24%; RR 2.22; 95% CI 1.30-3.70; P<0.003).
Diseño del estudio
Tipo
RCT (n=53)
PICO estructurado
Does a 5-mg warfarin loading dose improve the achievement of a stable therapeutic INR without overanticoagulation compared to a 10-mg loading dose in patients initiating warfarin therapy?
P
Población
53 patients initiating warfarin therapy with a target INR of 2.0 to 3.0, followed for 5 days.
I
Intervención
5-mg warfarin initial loading dose, with subsequent doses based on dosing algorithms
C
Comparador
10-mg warfarin initial loading dose, with subsequent doses based on dosing algorithms
O
Resultado
Proportion of patients whose INR values were between 2.0 and 3.0 on 2 consecutive daily determinations on days 3, 4, or 5 of the study and whose INR did not exceed 3.0 at any point during the studysurrogate
A 5-mg initial loading dose of warfarin is more effective than a 10-mg dose in achieving a stable therapeutic INR by day 4 or 5 without overanticoagulation.
Resultado numérico
Relative Risk: 2.22 (95% CI 1.3–3.7)
Tasa de eventos absoluta: 66% vs 24%
valor p: p=<.003
Resumen
BACKGROUND: Warfarin sodium therapy is usually initiated with a loading dose to reduce the time required to elevate the international normalized ratio (INR). Warfarin loading doses are associated with early overanticoagulation and the development of a potential hypercoagulable state; they also may not hasten achieving an INR value between 2.0 and 3.0. This study was designed to prospectively confirm our observation that a 5-mg warfarin sodium loading dose is as effective as a 10-mg loading dose in achieving a therapeutic INR for 2 consecutive days on days 3 and 4 or 4 and 5 of therapy. METHODS: Fifty-three patients initiating warfarin therapy with a target INR of 2.0 to 3.0 were randomly allocated to receive an initial dose of 5 or 10 mg of warfarin. Subsequent doses were based on dosing algorithms. The INR was measured daily for 5 days. The primary end point of the study was the proportion of patients whose INR values were between 2.0 and 3.0 on 2 consecutive daily determinations on days 3, 4, or 5 of the study and whose INR did not exceed 3.0 at any point during the study. RESULTS: Five (24%) of 21 patients in the 10-mg group and 21 (66%) of 32 patients in the 5-mg group achieved the primary end point (relative risk 2.22, 95% confidence interval 1.30-3.70 P < .003). A trend toward less overanticoagulation was seen in the 5-mg warfarin group. CONCLUSION: A 10-mg loading dose of warfarin is unlikely to be more effective than a 5-mg loading dose in achieving an INR of 2.0 to 3.0 by day 4 or 5 of therapy.