Effectiveness and safety of therapy with vitamin K antagonist in Italian patients aged 80 years or older: a multicentre retrospective study comparing Zeus algorithm with PARMA algorithm or manual therapy.

Background: Oral anticoagulant therapy (OAT) has constantly increased in the prevention of thromboembolism, above all in patients 80 years of age or older. The aim of this multicentre study was to evaluate efficacy and safety of vitamin K antagonist (VKA) in elderly patients managed with computer dosing algorithm compared with dosage decided by expert physicians. Materials and methods: Nine thrombosis Italian centres utilizing the “Zeus” dosing algorithm were involved. The “before-after” study enrolled patients managed firstly by medical staff (manual system) or with “PARMA” algorithm for twelve months from July 2008 to June 2009 and then with “Zeus” algorithm during the analogous period 2010 – 2011. Out of 7605 in OAT maintenance phase, 2281 were older than 80 years (mean age: 84.2). Data of these 2281 patients managed with both modalities were analysed. Results: Out of 2281 patients 80 years of age or older, 1776 underwent OAT for atrial fibrillation (AF). Dosing algorithm increased the OAT quality: time in therapeutic range (TTR) was significantly (p<0.001) higher during the Zeus period in comparison with the TTR during manual period (71.6% vs. 68.8%). The TTR achieved with Zeus was similar to that obtained with PARMA algorithm. In addition to this, patients managed with Zeus took a drug amount significantly (p<0.01) lower than that both suggested by Parma and that prescribed by expert physicians with a reduced number of adverse events. Conclusions: This study confirms that the effectiveness and safety of VKA therapy in patients 80 years of age or older increase with computer dosing algorithms.