ICAD: Clinical validation study of a new algorithm for oral anticoagualant dosing.

Introduction:

Oral anticoagulants are among the most widely used drugs and have a sizable risk of severe bleeding complications. Efforts to improve dosing quality in oral anticoagulant control include the use of computer algorithms. Since the 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.




Design, Setting and Participants:

This is adouble-blind randomized controlled trial among patients with an indication for long-term anticoagulant treatment at the Leiden Anticoagulation Clinic. There are two interventions: oral anticoagulant dosing supported by the new algorithm (ICAD) or oral anticoagulant dosing by the standard algorithm (TRODIS).
Main outcome measures are the percentage of time in therapeutic range, proportion of visits in which the algorithm gave a proposal and the proportion of proposals that was accepted by the physicians.

The equations used by most current algorithms are usually based on a simple pharmacodynamic model, which implies a linear function between the INR and the dosage. Our new algorithm consists of two sub models in which the first sub model describes the collective influence of all processes on the effect of the vitamin K antagonist and the second sub model describes the relationship between the dosage and the corresponding INR. The second sub model includes a variable parameter to reflect the sensitivity of the patient that may change over time. Because of the inclusion of a parameter which relfects the sensitivity of the patient we think it is better capable of proposing a doasage wich leads to an INR within the therapeutic range.

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Oral anticoagulant dosage supported by the new algorithm (ICAD) and oral anticoagulant dosage supported by the algorithm TRODIS.