predictors for inr-control in a well-managed warfarin treatment setting

Warfarin is well studied in patients with non-valvular atrial fibrillation (af). it has low complication rates for patients achieving individual time in therapeutic range (ittr) > 70%. the risk scores same-tt2r2 and prosper are designed to predict future ttr, but are derived from a heterogeneous population with generally low ittr. the aim of this study was to evaluate predictors for high and low ittr in an af population in sweden, where there is a generally good anticoagulation control. a retrospective register study based on swedish warfarin dosing system auricula, including 28,011 af patients starting treatment during 1 2006 to 31 2011. complications and risk factors were analysed and related to ittr. mean age was 73.7 (sd ± 9.5) years, with 42.0% women. mean cha2ds2-vasc score (sd) was 3.6 (± 1.7). for patients with ittr < 60% there were over three times higher prevalence of excessive alcohol consumption than for patients with ittr > 70% (3.7% vs. 1.1%). previous stroke were more prevalent for patients with high than low ittr (17.1% vs. 20.3%). concomitant comorbidities were associated with increased risk of poor ittr. in swedish af patients, excessive alcohol use is clearly associated with ittr below 60%. patients with previous stroke are more likely to get ittr above 70%, unlike those with concomitant disorders who more often have poor anticoagulation control. the same-tt2r2-score cannot be applied in sweden.