Abstract
Background Monitoring and strict control of anticoagulation therapy reduces the risk of thromboembolic or hemorrhagic events. The objective of this research was to explore the association of the quality of anticoagulation control with the occurrence of stroke, thrombotic or hemorrhagic events, or death during follow-up in patients with nonvalvular atrial fibrillation (NVAF) on vitamin K antagonists. Methods A retrospective and observational study was carried out in clinical practice (real world data). Data were collected on age, sex, income level, occupational status, ischemic stroke, thrombotic and hemorrhagic events, death, and the Charlson Comorbidity Index. Time in therapeutic range (TTR) was measured using TAONet software and TTR ≥60% was considered indicative of good anticoagulation control. Survival analysis was carried out using Kaplan-Meier curves and Cox regression models to compare time-to-event by quality of anticoagulation control. Determinants of anticoagulation quality were identified using logistic regression. Results Of 856 patients recruited, only 286 (33%) had a TTR ≥60%. Cox models including sociodemographic and clinical variables showed that the risk of all four events was much higher in the subsample with TTR <60% and the differences were statistically significant. Specifically, the hazard ratios (HRs) for this group were 1.94 (confidence interval [CI]: 1.13-3.30) for stroke, 1.60 (CI: 1.10-2.33) for thrombotic events, 1.61 (CI: 1.08-2.42) for hemorrhagic events and 2.97 (CIs: 1.86-4.75) for death. Conclusions The positive conclusion of the study was the markedly lower rate of events associated with TTR ≥60% and the negative conclusion was the low percentage of patients achieving good anticoagulation control. This implies that despite being “protected”, they continue to have a high risk of stroke, embolism, hemorrhagic complications and death. We believe it is necessary to develop and implement strategies to tackle this problem.