Evaluation of a mobile electronic assistant to aid in fluindione prescription: the INRPlus cluster randomized trial

Regular monitoring of the international normalized ratio (INR) is crucial for dose adjustment of vitamin K antagonists (VKA) to maximize time in therapeutic range (TTR). We compared the use of a mobile electronic assistant INRPlus which proposes patient-specific fluindione doses, to standard fluindione management in a cluster randomized controlled study.

Twenty clusters of six general practitioners were randomized to adjust fluindione doses in VKA-treated patients either using INRPlus or according to routine practice. TTR was measured over 6 months, along with time spent above or below the recommended INR range, frequency of measurements and related complications.

Of the 595 included patients, 551 were assessable (259 INRPlus, 292 control) and had a mean of 1.6 INR measurements/month. TTR was not significantly different between the two groups, 72.7% [Q1: 58.1%; Q3: 90%] in INRPlus patients and 71.2% [Q1: 54.8%; Q3: 88.2%] in control patients (p=0.445). At least 60% time within reference ranges was reported in 73.4% of INRPlus patients and 67.1% of control patients (relative risk 1.09, 95%CI 0.98-1.22, p=0.115). No significant differences were reported between the two groups for time outside reference ranges, frequency of measurements or complications. Eighty-two percent (82%) of patients complying with INRPlus-proposed doses spent more than 60% of TTR versus 66.9% of non-compliant patients and 67.1% of reference patients.

In this trial, the use of the INRPlus electronic assistant resulted in a non-significant improvement in TTR that may be due to a higher than expected TTR in the control group.