Warfarin用藥指導之成效評估

Assessing outcomes of patient education for receiving warfarin

簡麗卿(Li-Ching Chien)

指導教授 ： 黃耀斌

高雄醫學大學/藥學院/藥學研究所碩士在職專班/碩士(2012年)

摘要

研究背景:
Warfarin(商品名:Coumadin，中文名:可邁丁)是臨床上血栓疾病的有效治療藥物。但是warfarin是一個治療指數狹窄(therapeutic windows narrow)的藥物，常因病患個體基因差異、生活飲食習慣上的不同而導致血栓或出血事件發生。因此，除了監測病患凝血酶原時間(prothrombin time; PT)及國際標準比值(international normalized ratio; INR)之外，對病患的用藥教育也是不可或缺的一環；在美國，2003年起藥師針對住院病患提供完整的抗凝血劑藥事服務(Anticoagula- tion Management Service; AMS)，病患的預後良好，出血的併發症降低至0.7%，成效顯著。在台灣，藥師提升門診病患對warfarin認知程度可降低病患出血風險，使病患疾病獲得良好控制已在過去的研究中證實。住院病患族群的疾病嚴重度較高，相較於門診病患需要更完善的用藥指導及後續追蹤來確保病患的療效及安全性。
研究目的:
主要探討藥師提供住院病患warfarin用藥指導後，病患疾病治療的成效、安全性。
研究方法:
本研究採病歷回溯分析方法，分析2010年9月1日至2011年8月31日南部某區域教學醫院住院病患中第一次使用warfarin治療之住院病患，在住院期間藥師提供用藥指導服務後，病患出院後INR值的控制範圍、不良反應的發生率及危險因子的探討。
研究結果:
研究共納入91位病患，平均年齡65.0± 14.2歲，年齡分布以70~79歲為主，使用warfarin主要被診斷為DVT (deep vein thrombus)佔28.6%，其餘尚有被診斷為AF (atrial fibrillation)及肺栓塞等。分析接受用藥指導者認知前後測，發現用藥指導後認知具有顯著提升(p<0.01)。
本研究之對象，出院後INR平均值約1.7~2.1之間，第一次回診INR值明顯高於第三個月及第六個月之監測值；出院後6個月內藥物不良反應發生率為12.1%，出血及血栓不良反應則各有5人；進一步分析發生不良反應之原因，主要與INR值偏高有關，在年齡、藥物劑量、性別、併用交互作用藥物個數及病患本身危險因子個數上皆無明顯相關性存在。
結論:
本研究分析藥師介入warfarin衛教對於病患服藥後之影響，發現藥師給予病患用藥指導可增進病患藥物使用認知，讓病患了解服藥後必須注意的相關事項。雖然本實驗無對照組可比較介入之影響力是否具有統計上意義，但從臨床數據解讀中可以發現，對於INR值控制，仍有臨床意義。由此可知藥師介入Warfarin衛教對於病患服藥後INR值控制有一定影響力，對病患醫療照護及服藥安全性上有實質的助益。

關鍵字

口服抗凝血劑 ； 病患教育 ； 藥事服務

並列摘要

Background:
Warfarin is an oral anticoagulant which is commonly used in the treatment of thrombotic diseases. To ensure safe and effective dosing of warfarin, the international normalised ration (INR), calculated from blood tests, is monitored. However, the safety range for the INR is usually narrow, and the INR may be affected by factors such as interaction with other medication, vitamin K level in the diet, and even the genotype of the person. Therefore, it is necessary to take extra precautions in using warfarin. In 2003, the implementation of a pharmacist-led Anticoagulation Management Service (AMS) for inpatients in the United States has lowered the bleeding complication rate to 0.7%, while studies in Taiwan demonstrated that promoting precaution information through patient education reduced complications arising from warfarin treatment. Careful monitoring and discussing possible side-effects especially with new inpatients using warfarin for the first time are necessary.
Purpose:
We hypothesised that a Pharmacist-Conducted Patient Education and Counselling service for inpatients will increase the efficacy of warfarin therapy, minimise the complication.
Method:
This is a retrospective review of inpatients at a medical centre in southern Taiwan from September 2010 to August 2011. The patients recruited in this study for analysis were first-time users of warfarin treatment. Patients who took part in the Pharmacist-Conducted Patient Education and Counselling programme during hospitalisation were assessed and compared with match control. Parameters such as blood-test INR, incidence and cause of warfarin complications.
Result:
There were 91 patients met our inclusion criteria, and their charts were selected for analysis. The mean age is 65±14.2 years old, with a range between 70 to 79 years old. The major indications for anticoagulant therapy of warfarin was DVT, with a percentage of 28.3%. The rest indications are AF and pulmonary embolism. We found the outcome of pharmacist-conducted intervention has significantly improving of warfarin knowledge test (p<0.01).
The mean INR after discharge of our study group is between 1.7 to 2.1. The INR of first visit in OPD after discharge was higher than the third and sixth month after receiving warfarin treatment without statistical significance, but still found to show a clinical meaning of benefit in INR control. The incidence rate of adverse reaction is 12.1%. Bleeding and thrombosis with a number of 5 respectively. Consider of the cause to adverse reactions, we found it correlated to the range of INR, instead of age, warfarin dosage, gender, drug-drug interaction or any risk factors.
Conclusions:
In this study, we analyzed the impact of pharmacist-conducted intervention to warfarin indicated patients regarding additional information to warfarin treatment. We found it has most improving outcomes in the group with an educational level under senior high school. Though we didn’t design a control group to confirm whether the intervention is significantly beneficial, we still find clinical meanings on INR control within each subject before and after intervention. In conclusion, the pharmacists’ service of warfarin indicted consulting improves drug-used safety and has a positive impact on clinical care.

並列關鍵字

Anticoagulant ； patient education ； pharmaceutical service

參考文獻

1. Bell RG, Sadowski JA, Matschiner JT. Mechanism of action of warfarin. Warfarin and metabolism of vitamin K1. Biochemistry 1972;11:1959-1962.

2. Hirsh J, Dalen J, Anderson DR, Poller L, Bussey H, Ansell J, et al. Oral anticoagulants: mechanism of action, clinical effectiveness, and optimal therapeutic range. Chest 2001;119:8S-21S.

3. Hirsh J, Fuster V, Ansell J, Halperin JL. American Heart Association/American College of Cardiology Foundation guide to warfarin therapy. Circulation 2003;107:1692-1711.

4. Keeling D, Baglin T, Tait C, Watson H, Perry D, Baglin C, et al. Guidelines on oral anticoagulation with warfarin - fourth edition. Br J Haematol 2011;154:311-324.

5. Breckenridge A. Oral anticoagulant drugs: pharmacokinetic aspects. Semin Hematol 1978;15:19-26.