Therapeutically active anticoagulation with VKA during total knee arthroplasty (start of VKA 10 to 14 days preoperatively) was demonstrated to cause a greater need for blood transfusions and a lower postoperative hematocrit than a regimen without any effect of VKA (started the evening before surgery) during surgery. Vitamin K antagonists are temporarily stopped to allow for invasive procedures. In addition, other important groups of patients, such as those with venous thromboembolism or mechanical heart valve prosthesis use VKA. Atrial fibrillation is prevalent in about 2.3 million people in the United States and one million are receiving warfarin. It has been reported that 36% of patients, 50 to 99 years of age, with atrial fibrillation are using VKA with a gradual increase over time. With increasing life expectancy, and thereby also increasing prevalence of atrial fibrillation, a larger proportion of the population is using vitamin K antagonists (VKA). Whenever normal hemostasis is considered crucial for the safety, the INR should be checked again before the invasive procedure. Conclusionīaseline INR, but not the size of the maintenance dose, is associated with the rate of normalization of prothrombin time after stopping warfarin, but it has limited utility as predictor in clinical practice. The positive predictive value of baseline INR with a cut off at > 3.0 was only 15% and for INR > 3.5 it was 33%. The odds ratio for being in the normal group was 0.27 (95% confidence interval 0.12–0.62) for each unit baseline INR increased. Baseline INR was the only variable significantly associated with classification as S in stepwise logistic regression analysis (p = 0.003). Eight of the S-patients required reversal with vitamin K one day before surgery and in another case surgery was cancelled due to high INR. Of 202 patients, 14 (7%) were classified as S. An INR value of 1.6 or higher on the day of surgery or requirement for reversal with vitamin K the day before surgery were criteria for slow return (S) to normal INR. MethodsĬlinical data were collected retrospectively from consecutive cases from two cohorts, who stopped warfarin 6 days before surgery. We sought to identify easily available clinical characteristics that may influence the rate of normalization of prothrombin time when warfarin is stopped before surgery or invasive procedures.

Despite this routine, some patients still have high International Normalized Ratio (INR) values on the day of surgery and the procedure may be cancelled. Anticoagulation with warfarin should be stopped 4–6 days before invasive procedures to avoid bleeding complications.

Pt inr normal range on warfarin