Egan Gregory, Ensom Mary H H
BScPharm, ACPR, PharmD, is a Clinical Pharmacy Specialist in Neurology, Vancouver General Hospital, Vancouver, British Columbia.
BS(Pharm), PharmD, FASHP, FCCP, FCSHP, FCAHS, is a Professor in the Faculty of Pharmaceutical Sciences and Distinguished University Scholar, The University of British Columbia, and a Clinical Pharmacy Specialist, Children's and Women's Health Centre of British Columbia, Vancouver, British Columbia. She is also the Editor of the CJHP .
Can J Hosp Pharm. 2015 Jan-Feb;68(1):33-47. doi: 10.4212/cjhp.v68i1.1423.
The choice of whether to monitor anti-factor Xa (anti-Xa) activity in patients who are obese and who are receiving low-molecular-weight heparin (LMWH) therapy is controversial. To the authors' knowledge, no systematic review of monitoring of anti-Xa activity in such patients has been published to date.
To systematically ascertain the utility of monitoring anti-Xa concentrations for LMWH therapy in obese patients.
MEDLINE (1946 to September 2014), the Cochrane Database of Systematic Reviews, Embase (1974 to September 2014), PubMed (1947 to September 2014), International Pharmaceutical Abstracts (1970 to September 2014), and Scopus were searched using the terms obesity, morbid obesity, thrombosis, venous thrombosis, embolism, venous thromboembolism, pulmonary embolism, low-molecular weight heparin, enoxaparin, dalteparin, tinzaparin, anti-factor Xa, anti-factor Xa monitoring, anti-factor Xa activity, and anti-factor Xa assay. The reference lists of retrieved articles were also reviewed.
English-language studies describing obese patients treated with LMWH or reporting anti-Xa activity were reviewed using a 9-step decision-making algorithm to determine whether monitoring of LMWH therapy by means of anti-Xa activity in obesity is warranted. Studies published in abstract form were excluded.
The analysis showed that anti-Xa concentrations are not strongly associated with thrombosis or hemorrhage. In clinical studies of LMWH for thromboprophylaxis in bariatric surgery, orthopedic surgery, general surgery, and medical patients, and for treatment of venous thrombo embolism and acute coronary syndrome, anti-Xa activity can be predicted from dose of LMWH and total body weight; no difference in clinical outcome was found between obese and non-obese participants.
Routinely determining anti-Xa concentrations in obese patients to monitor the clinical effectiveness of LMWH is not warranted on the basis of the current evidence. Circumstances where measurement of anti-Xa concentration may help in clinical decision-making in either obese or non-obese patients would be cases where elimination of LMWH is impaired or there is an unexpected clinical response, as well as to confirm compliance with therapy or to identify deviation from predicted pharmacokinetics.
对于肥胖且接受低分子量肝素（LMWH）治疗的患者，是否监测抗Xa因子（抗Xa）活性存在争议。据作者所知，迄今为止尚未发表关于此类患者抗Xa活性监测的系统评价。
系统确定监测肥胖患者LMWH治疗中抗Xa浓度的效用。
使用肥胖症、病态肥胖、血栓形成、静脉血栓形成、栓塞、静脉血栓栓塞、肺栓塞、低分子量肝素、依诺肝素、达肝素、替扎肝素、抗Xa因子、抗Xa因子监测、抗Xa因子活性和抗Xa因子测定等术语检索了MEDLINE（1946年至2014年9月）、Cochrane系统评价数据库、Embase（1974年至2014年9月）、PubMed（1947年至2014年9月）、国际药学文摘（1970年至2014年9月）和Scopus。还对检索到的文章的参考文献列表进行了审查。
使用9步决策算法对描述接受LMWH治疗的肥胖患者或报告抗Xa活性的英文研究进行审查，以确定是否有必要通过肥胖患者的抗Xa活性监测LMWH治疗。以摘要形式发表的研究被排除。
分析表明，抗Xa浓度与血栓形成或出血没有密切关联。在LMWH用于减肥手术、骨科手术、普通外科手术和内科患者的血栓预防以及静脉血栓栓塞和急性冠状动脉综合征治疗的临床研究中，抗Xa活性可根据LMWH剂量和总体重预测；肥胖和非肥胖参与者的临床结局没有差异。
根据目前的证据，在肥胖患者中常规测定抗Xa浓度以监测LMWH的临床有效性是不必要的。在肥胖或非肥胖患者中，抗Xa浓度测量可能有助于临床决策的情况包括LMWH清除受损或出现意外临床反应的情况，以及确认治疗依从性或识别与预测药代动力学的偏差。
