Improved control of oral anticoagulant dosing: a randomized controlled trial comparing two computer algorithms

Background: Efforts to improve dosing quality in oral anticoagulant control include the use of computer algorithms. As current algorithms are simplistic and give dosage proposals in a small fraction of patients, we developed an algorithm based on principles of system and control engineering that gives proposals in nearly all patients. Objective: To evaluate the new algorithm in clinical practice. Patients and methods: We conducted a double-blind randomized controlled trial among 712 patients with an indication for long-term anticoagulant treatment at the Leiden Anticoagulation Clinic. We compared oral anticoagulant dosing supported by the new algorithm (ICAD) with the standard algorithm (TRODIS). Results: The percentage of time spent in the therapeutic range was similar for the new and standard algorithm groups, 79.8% vs. 80.2% (difference 0.4%, 95% Cl: -1.7-2.6%). The new algorithm produced a dosage proposal in 97.5% of visits, and the standard algorithm in 60.8% (difference 36.7%, 95% CI: 35.4-38.0%). Of proposals of the new algorithm, 79.3% were accepted by the physician vs. 90.9% for the standard algorithm (difference 11.6%, 95% Cl: 10.2-13.0%). This implies that the new algorithm gave an acceptable proposal in 77.4% of all patient visits vs. 55.3% for the standard algorithm (difference 22.1%, 95% CI 20.423.8%). Conclusions: Substantially more dosage proposals were generated and accepted with the new than with the standard algorithm, and the new algorithm will therefore improve the efficiency of anticoagulant monitoring without loss of quality.