Quality of Oral Anticoagulation in Atrial Fibrillation Patients at a Tertiary Hospital in Brazil

Abstract Background Atrial fibrillation (AF) affects 0.5% to 2.0% of the general population and is usually associated with cardiac structural diseases, hemodynamic damage, and thromboembolic complications. Oral anticoagulation prevents thromboembolic events and is monitored by the international normalized ratio (INR). Objectives To evaluate INR stability in nonvalvular AF patients treated with warfarin anticoagulation, to evaluate thromboembolic or hemorrhagic complications, and to identify the group at higher risk for thromboembolic or hemorrhagic events. Methods Data from the medical records of 203 patients who received medical care at a tertiary hospital in Brazil were reviewed, and the time in therapeutic range (TTR) was calculated using the Rosendaal method. The possible TTR influencing factors were then analyzed, and the relationship between the TTR and thromboembolic or hemorrhagic events was calculated. The level of significance was 5%. Results The mean TTR was 52.2%. Patients with INR instability in the adaptation phase had a lower mean TTR (46.8%) than those without instability (53.9%). Among the studied patients, 6.9% suffered hemorrhagic events, and 8.4% had a stroke. The higher risk group for stroke and bleeding consisted of patients with INR instability in the adaptation phase. Conclusions The quality of anticoagulation in this tertiary hospital in Brazil is similar to that in centers in developing countries. Patients with greater INR instability in the adaptation phase evolved to a lower mean TTR during follow-up, had a 4.94-fold greater chance of stroke, and had a 3.35-fold greater chance of bleeding. Thus, for this patient group, individualizing the choice of anticoagulation therapy would be advised, considering the cost-benefit ratio.

摘要 背景：心房颤动（Atrial fibrillation，AF）在普通人群中的患病率为0.5%~2.0%，通常与心脏结构性疾病、血流动力学损伤及血栓栓塞并发症相关。口服抗凝治疗可预防血栓栓塞事件，并需通过国际标准化比值（international normalized ratio，INR）进行监测。研究目的：评估接受华法林（warfarin）抗凝治疗的非瓣膜性心房颤动患者的INR稳定性，分析其血栓栓塞或出血并发症发生情况，并识别血栓栓塞或出血事件的高风险人群。研究方法：回顾性分析巴西某三级医院203例就诊患者的病历资料，采用罗森达尔法（Rosendaal method）计算治疗范围内时间（time in therapeutic range，TTR）；随后分析影响TTR的潜在因素，并探究TTR与血栓栓塞或出血事件之间的关联，检验水准设定为5%。研究结果：本研究队列患者的平均TTR为52.2%。适应期存在INR不稳定的患者，其平均TTR（46.8%）低于无INR不稳定的患者（53.9%）。纳入研究的患者中，6.9%发生出血事件，8.4%发生脑卒中；适应期存在INR不稳定的患者为脑卒中及出血事件的高风险人群。研究结论：巴西该三级医院的抗凝治疗质量与发展中国家同类医疗中心水平相当。适应期INR不稳定程度更高的患者，随访期间的平均TTR更低，发生脑卒中的风险升高4.94倍，出血风险升高3.35倍。因此，针对该类患者群体，应结合成本效益比个体化选择抗凝治疗方案。