Compliance and stability of INR of two oral anticoagulants with different half-lives: a randomised trial

Abstract

SummaryThe aim of the study was to assess the respective roles of the half-life of elimination of oral anticoagulants and patient education as causes of instability of anticoagulation level in patients on oral anticoagulant therapy. Patients were randomised to receive either warfarin (long half-life) or acenocoumarol (short half-life) and either intensive or standard education, according to a factorial design. Instability of oral anticoagulant therapy was evaluated by the percentage of INRs and the time within the target range, and the variability between successive measurements. Compliance was assessed by means of electronic pill bottles. Eighty-six patients were included. Apart from the variability index, instability was similar between groups. Correlations between compliance and instability were observed only in the acenocoumarol group. No difference was found between the education groups. In patients starting oral anticoagulant therapy, dose determination may be the most important factor contributing to instability.

Effect of switching from acenocoumarol to phenprocoumon on time in therapeutic range and INR variability: A cohort study

“…A retrospective study focussing on self-managed patients found a higher TTR on phenprocoumon than on warfarin [15]. A French randomised controlled trial showed no difference in TTR between patients initiated with warfarin versus those with acenocoumarol, but INR variability was lower in the warfarin group [16]. This implies that phenprocoumon (with the longest halflife) might lead to a higher TTR than warfarin (with the intermediate half-life); warfarin, in turn, could cause a higher or similar TTR to acenocoumarol (with the shortest half-life).…”