CHAPTER 2 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. Since 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 We evaluated 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 therapeutic range was similar for the new and standard algorithm group, 79.8% versus 80.2% (Diff 0.4%, 95%CI –1.7% to 2.6%). The new algorithm produced a dosage proposal in 97.5% of visits and the standard algorithm in 60.8% (Diff 36.7%, 95%CI 35.4%-38.0%). 79.3 % of proposals of the new algorithm were accepted by the physician versus 90.9% for the standard algorithm (Diff 11.6%, 95%CI 10.2%-13.0%). This implies that the new algorithm gave an acceptable proposal in 77.4% of all patient visits versus 55.3% for the standard algorithm (Diff 22.1%, 95%CI 20.4%-23.8%). 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. Comparison of two anticoagulant dosing algorithms 21