INR Deviations in Hemodialyzed Patients under Low Dose Oral Anticoagulant Therapy

Abstract

The aim of this retrospective study was to evaluate the International Normalized Ratio (INR) in hemodialyzed uremic patients under treatment with oral anticoagulation drugs. Eleven out of one hundred and forty-two uremic hemodialyzed patients in our unit were included in the study. These 11 patients aged from 70 to 85 (mean: 76 years) were under oral anticoagulation treatment for protection from thromboembolic events. They received 1 mg acenocumarol daily with the therapeutic goal of achieving an INR between 2 and 2.5 units. During the last year, the number of total INR determinations was 129. Based on the INR levels, measurements were classified into three categories of anticoagulation, termed “under-anticoagulation”, “target-anticoagulation”, and “over-anticoagulation”. The number, the percentage, and the mean value (±SD) of INR measurements for each category, respectively, were under-anticoagulation: 39, 30%, 1.78 ± 0.14; target-anticoagulation: 48, 37.5%, 2.20 ±0.14; and over-anticoagulation: 42, 32.5%, 3.14 ± 0.64. The mean value ±SD of all INR determinations (n=129) was 2.34 ±0.65. No thromboembolic or major bleeding events occurred in our patients with these INR. In conclusion, in elderly, hemodialyzed uremic patients with indications for oral anticoagulation treatment, adequate and safe INR levels can be achieved in a high proportion without serious deviations from the therapeutic goal by using low doses of drugs. Therefore, oral anticoagulation therapy should not be considered automatically contra-indicated in this patient group.

Cohort study on the quality of oral anticoagulation therapy in chronic haemodialysis patients treated with phenprocoumon

“…In our study, in spite of a higher frequency of INR measurements compared to other studies (measurements every 21-31 days [28,29]) the percentage of INR in target range did not exceed 54%. The indication for OAT may influence the percentage of INR measurements in target range both as an independent risk factor and via the height and width of target range [7,38,39].…”

“…This is the first study analysing the quality of OAT control in patients treated with phenprocoumon in a chronic haemodialysis population. [29]. Both individual and population based percentage of measurements in target range can be biased by more frequent measurements in patients with difficult adjustment of OAT, resulting in an underestimation of OAT control [37].…”

“…Swiss Med Wkly. 2013;143:w13730 2-3) [21,28,29]. The absolute height of target range also can influence the percentage of INR measurements in target range.…”

“…Additionally, vascular accesses such as arterio-venous graft and permanent tunnelled central venous catheter (PC) present an increased risk of local or systemic thromboembolism [24][25][26][27]. However, only few studies have been published on the control of OAT in end stage renal disease (ESRD) and dialysis [21,28,29]. There is to date no study evaluating phenprocoumon in haemodialysis patients.…”

Oral Anticoagulant Therapy in Patients Receiving Haemodialysis: Is It Time to Abandon It?

“…The ability of blood proteins, especially albumin, to bind warfarin is very strong, and therefore changes in their concentration during HD result in significant changes in the concentrations of the active ingredient of the medicine, INR, and, consequently, treatment complications. In a retrospective study of 142 haemodialysed patients who received acenocoumarol for typical indications at a dose of 1 mg a day for a year, Gompou et al [27] demonstrated that 30% of the INR values determined at this time were below target values, 37% were in the therapeutic range, and nearly 33% exceeded therapeutic values. Admittedly, there is no information regarding the severe complications of such treatment in the report, but the fact that OACs were overdosed in 1/3 of the cases seems alarming.…”